Medical Research Council of Canada therapeutic trial of human growth hormone: first 5 years of therapy H. Guyda,* md, frcp[c]; H. FRiESEN,f md, frcp[c]; J.D. Bailey,J md, frcp[c]; G. Leboeuf,§ md; J.C. BECK,f MD, FRCP[C]
Summary: The Medical Research Council of Canada has initiated human growth hormone (hGH) therapy in 151 patients with documented complete hGH deficiency that was idiopathic in 76% of cases, secondary to craniopharyngioma (organic) ki 17% and of varied cause in 7%. Approximately 50% of the patients with idiopathic disease had isolated hGH deficiency; during therapy thyroid deficiency developed in five patients and cortisol deficiency in three. A similar increase in mean height velocity occurred in the first treatment phase for patients less than 12 years old (0.93 ± 0.30 cm/mo) and those 12 years and older (0.86 ± 0.29 cm/mo). Although subsequent courses of hGH therapy yielded significantly diminished response in both age groups, this diminution was not progressive: the height velocity of the younger patients returned to 0.82 ± 0.26 cm/mo in the fifth therapy phase. The mean height velocity attained at the optimal dosage (0.20 to 0.29 units/kg three times per week) for each age group did not differ significantly. Despite therapy being carried out for only 6 months of the year, normal increment ratios for height age and bone age against chronologic age were observed in the patients with idiopathic disease. ln only four patients did treatment failure occur, and three of these were more than 20 years old. The addition of fluoxymesterone (10 mg/d) to the hGH therapeutic regimen (15 units/wk), when diminished response to hGH alone became evident, promoted an enhanced growth response in 9 of 11 older patients. These data indicate that age of the patient and dosage of hGH, but not diagnostic category, were important influences on the response to therapy. Younger patients responded best and maintained a higher mean growth velocity than older patients during intermittent hGH
therapy.
From the departments of pediatrics* and medicine J McGill University, Montreal; department of physiology,t University of Manitoba, Winnipeg; department of pediatrics,| Hospital for Sick Children, Toronto; and department of endocrinology,! Hdpital Sainte Justine, Montreal flCurrent address: Suite 310, 350 Parnassus Ave., San Francisco, CA 94117, USA Supported by Medical Research Council of Canada grant no. MA 2525 Reprint requests to: Dr. H. Friesen, Professor and head, Department of physiology, University of Manitoba, 770 Bannantyne Ave., Winnipeg, Man. R3E 0W3
Resume: Le ConseH de recherches medicales du Canada a utilise I'hormone de croissance humaine (hGH) pour traiter 151 malades souffrant d'une insuffisance complete en hGH parfaitement prouvee. Cette deficience etait idiopathique dans 76% des cas, secondaire a un craniopharyngiome (d'origine organique) dans 17% des cas et relevait de causes diverses chez 7%. Pres de 50% des malades dont la pathologie etait de nature idiopathique presentaient une insuffisance isol6e en hGH; au cours de traitement on a note une insuffisance thyroidienne chez cinq malades et une insuffisance en hydrocortisone chez trois autres. Une augmentation similaire dans la vitesse de croissance moyenne a ete cortstat6e durant la premiere phase therapeutique tant chez les malades de moins de 12 ans (0.93 ± 0.30 cm/mo) que chez ceux Sges de 12 ans et plus (0.86 ± 0.29 cm/mo). Les s6ances therapeutiques de hGH subsequentes ont abouti a une diminution notable de la reaction clinique dans les deux groupes d'Sge, mais cette diminution n'a pas ete progressive: la vitesse de croissance de la taille des jeunes malades est revenue a 0.82 ± 0.26 cm/mo durant la cinquieme phase du traitement. La vitesse moyenne de croissance obtenue dans chaque groupe d'age avec la posologie optimale (0.20 a 0.29 unites/kg trois fois par semaine) ne differait pas significativement. En depit du fait que le traitement n'ait ete appliqu6 que durant 6 mois chaque annee, les rapports de I'augmentation normale pour I'age suivant la taille et pour Idge osseux, par rapport a I'dge chronologique, ont ete constates chez les malades souffrant de la maladie idiopathique. Le traitement n'a echoue que chez quatre malades et trois d'entre eux avaient plus de 20 ans. Quand la diminution de la reaction clinique au seul traitement avec la hGH devenait evidente, l'addition de fluoxymesterone (10 mg/d) au traitement a la hGH (15 unites/semaine), a permis d'obtenir une amelioration de la reaction de croissance chez 9 malades Sges sur 11. Ces donnees indiquent bien que I'Sge du malade et la posologie de hGH mais non la categorie diagnostique, sont les facteurs qui exercent une influence importante sur les resultats therapeutiques. Au cours d'un traitement intermittent a la hGH ce sont les jeunes malades qui ont le mieux reagi et qui ont pu maintenir un rythme de croissance plus eleve que les malades plus ages.
CMA JOURNAL/JUNE 7, 1975/VOL. 112 1301
Numerous studies have now documented that children de¬ ficient in growth hormone will respond to the administra¬ tion of low doses of human growth hormone (hGH) with an increase in linear growth velocity.1"8 Many of these studies have suffered from various defects, the most notable of which include small numbers of patients studied for an insufficient length of time, variability in the extraction procedure and source (embalmed v. nonembalmed) of hGH and a multiplicity of study design. As a result it has been difficult to answer such questions as (a) What is the best selection procedure for patients likely to benefit from hGH therapy? and (b) How is the influence of such factors as age of the patient, skeletal maturation, dosage of hGH, and associated therapy (namely cortisone, levothyroxine or androgen therapy) on the observed response best deter¬ mined? For these reasons the Medical Research Council of Canada agreed to undertake a collaborative therapeutic trial of hGH in Canada on a national scale with rigid criteria for patient acceptance into the study, a uniform and clearly defined standard protocol for all patients, and compilation of all obtained data in one central facility for statistical evaluation. This report documents the results obtained during the first 5 years of this study. Material and methods To date 151 patients have entered our study. Most university medical faculties in Canada have an assigned physician-coordinator who submits the records of potential can¬ didates to a central selection committee. Once the patient is approved for therapy the same coordinator then directs the hGH therapy for the patient at a local level. Anthropometric, clinical, radiographic and biochemical data are col¬ lected every 6 months on all patients and forwarded to the central facility at the University of Manitoba (previously at McGill University) for incorporation into a computer tape program. The first group of patients began therapy in January 1968 and this review includes data available as of July 1973.
Diagnosis Pituitary function: Only patients with documented hGH deficiency were studied; those with all other categories of hypopituitarism, including Turner's syndrome, delayed growth and adolescence, and intrauterine growth retarda¬ tion, were excluded. HGH deficiency has been defined as a failure of serum hGH concentration, as determined by radioimmunoassay, to respond to at least two provocative stimuli: insulininduced hypoglycemia and arginine hydrochloride infusion. While other provocative stimuli, such as levodopa, glu¬ cagon, tolbutamide plus glucagon, exercise and sleep re¬ lease,9'10 have been shown to induce hGH release, testing with them was not required for inclusion in this study. All patients were required to be chemically euthyroid at the time of the hGH stimulation studies. If severe constitu¬ tionai delay with impaired release of hGH due to a deficiency in sex hormones was suspected, studies were
performed after pretreatment with either estrogens or androgens.11'14 HGH was measured by radioimmunoassay15 at the central facility for all patients, thus excluding interlaboratory assay differences. If values did not exceed 5.0 ng/ml at any time during any of the stimulation tests the patient was considered a potentially suitable candidate for hGH therapy, provided the additional criteria indicated below were also met. Additional assessment of pituitary function included the following: 1. Status of thyroid-stimulating hormone (TSH; thyro¬ tropin). Serum thyroxine estimation more recently and protein-bound iodine estimation originally; radioactive 1302 CMA JOURNAL/JUNE 7,
1975/VOL. 112
iodine uptake before and, in some cases, after TSH stimula¬ tion; response of TSH to thyrotropin-releasing hormone in selected cases; and serum TSH and thyroid antibody de¬ terminations, when indicated, were performed. Interpreta¬
was based on the laboratory criteria in the diagnostic centre where the patient was evaluated. 2. Status of adrenocorticotropic hormone (ACTH). Originally the urinary corticoid response to oral metyrapone was used to determine endogenous ACTH status. However, more recently, documentation of morning and evening serum cortisol values and serum cortisol responses to insulin-induced hypoglycemia by competitive protein-binding assay have been used to document indirectly ACTH de¬ ficiency.16,17 If the increase in serum cortisol value was less than twofold, ACTH stimulation to exclude primary adre¬ nal failure has been carried out in most instances. 3. Gonadotropin status. All patients were classified from clinical photographs according to the stages of Marshall and Tanner.18,19 Serum concentrations of luteinizing and follicle-stimulating hormones are being determined by ra¬ dioimmunoassay in most of the study population and the results will be reported separately by C. Faiman and J.S.D. Winter. 4. Prolactin status. Serum prolactin was determined by radioimmunoassay in all patients and a preliminary report has appeared.20 5. Posterior pituitary status. Determination of urinary concentrating ability after an overnight fast or prolonged dehydration was used to assess the status of antidiuretic hormone (ADH) in the absence of clinical diabetes insipidus. Additional criteria for patient selection: Twice annually the patient-selection committee met to select candidates for the study. Major criteria included absolute hGH deficiency (on the basis of a lack of significant hGH response to both insulin and arginine tests), a height that was at least three standard deviations and usually more than four standard deviations below the normal mean for age, an interval growth rate for 1 year of less than 0.40 cm/mo, and skel¬ etal maturation or bone age, estimated according to the method of Greulich and Pyle,21 that was delayed at least two standard deviations below the normal mean for age. Radiographs of the sella turcica were obtained on all patients initially and on patients with craniopharyngioma annually thereafter. "Height age" was determined according to the method of Wilkins.22 Most patients were prepubertal (Tanner stage I) before inclusion in the study. However, certain exceptions were made for patients considered to have limited growth potential because of rapidly advancing spontaneous puberty at the time of initial consideration. (These exceptions will be dealt with separately below.) Chromosome determinations on buccal smears were con¬ sidered essential for all female patients to exclude those with Turner's syndrome and its variants. Patients receiving sex steroids before consideration were not accepted into the study. Treatment protocol In all patients there was a pretreatment period of at least 6 months (phase 01), during which time interval growth determinations, complete assessment of pituitary function, assessment of skeletal maturation and other pertinent studies were performed. Each patient then began 6 months of hGH therapy followed by 6 months with¬ out hGH therapy. The 6-months alternating schedule was continued as long as an accelerated growth velocity continued. Patients were arbitrarily assigned to a dosage regimen of either 2 or 5 units given by intramuscular in¬ jection three times per week, for a total dose of 6 or 15 units/wk. If growth velocity was insufficient (less than 0.35 cm/mo) with the smaller dose the patient was
tion of results
given
the larger dose during his next course of therapy. Patients with a diminished response to the larger dose were then included in an additional protocol, which added 10 mg/d of fluoxymesterone (Halotestin) to the 15 units/wk of hGH. This combined therapy followed a 6-months period of treatment with fluoxymesterone alone. This latter treat¬ ment group consisted of the oldest patients, including eight males and three females to date. Treatment in this group was continued, if successful, until satisfactory height was attained, growth ceased because of advanced skeletal ma¬ turation, indicative of epiphyseal fusion, or the patient wished to be removed from the study. Preparation of hGH HGH was prepared, according to a modification of the method of Raben,23 from human pituitary glands removed at autopsy (under the auspices of the Committee on Human Pituitary Hormones, sponsored by the Medical Research Council of Canada). This program yields approximately 10 000 pituitary glands per year, which is insufficient to maintain all patients requiring growth hormone in Canada on continuous hGH therapy. In part this has necessitated the alternating 6-months therapy protocol. The potency of the various batches of hGH used during the study varied from 0.68 to 1.60 IU/mg, as determined by bioassay (the 10-day increase in body weight in hypophysectomized rats).* The hGH to be administered was kept in vials containing 10 IU of the hormone. Determination of antibodies to hGH and prolactin The development of antibodies to hGH was assessed every 6 months on all patients during the study in the laboratory that performed the hGH radioimmunoassays. All patient sera were screened at a dilution of 1:10 for the presence of antibody binding to hGH labelled with radio¬ active iodine, after incubation at 4°C for 24 hours and separation by charcoal. All sera positive at this original dilution were then further diluted until levels of binding similar to those of control sera at a 1:10 dilution were achieved. This dilution was then used to approximate the specific binding of the hGH tracer by that patient's serum. No attempts were made to determine actual binding capa¬ city for hGH in patients with demonstrable antibodies. Autoantibodies to human prolactin were determined in an identical manner using human prolactin labelled with radioactive iodine. Assessment of growth response At the beginning and end of each 6-months therapy period the patient's height, weight, skeletal maturation (ac¬ cording to the Greulich and Pyle atlas21) and sexual stage was recorded, a clinical photograph was obtained and serum was screened for antibodies to hGH. During the period of therapy the height was measured every 2 months by the physician-coordinator. All patient data were forwarded to the central facility and entered in the computer tape program for statistical analysis. Growth velocity (cm/mo) was determined during each 6-months phase. The dose of hGH received was calculated in terms of the units per kilogram given three times per week; because of the great changes in weight during therapy in many patients, a mean of the starting and ending weight for each treat¬ ment phase was used to perform this calculation. Initial observations in this study and by other groups suggested that older patients with hGH deficiency respond less well during therapy than younger patients; therefore, the data were adjusted so that calculations were performed sepa¬ rately for all patients less than 12 years of age and all patients 12 years and older. Thus, increments in growth 'Endocrine Laboratories of Madison, Inc,
Madison, Wisconsin.
velocity
in relation to both age and units/kg of hGH administered could be determined. Other variables that possibly affect the observed growth response, including additional hormone therapy (levothyroxine and cortisone) and spontaneous or induced puberty, were assessed for their influence on each diagnostic cate¬ gory of patients. The influence of these variables on ob¬ served growth velocity as well as on the subsequently de¬ rived increment ratios for height age (A HA), bone age (A BA) and chronologic age (A CA) was also assessed, as was the influence of the development of antibodies to hGH on growth velocity. Statistical analysis All statistical analyses were performed using the Student's / test.
Results
Physical data As indicated in Table
I, the distribution of
causes
of
hypopituitarism in the patients included in this trial is similar to that described for most reported groups of pa¬ tients with hypopituitarism;1"8'24'26 that is, 76% of the pa¬ tients were considered to have idiopathic disease, and males predominated in this category (2.7:1). About 17% of our patients had organic disease (craniopharyngioma) and about 7% were placed in the "other" diagnostic category five patients with familial idiopathic hypopituitarism (in¬ cluding two female siblings), three patients with disease of traumatic origin, one patient with histiocytosis X, one patient with a chromophobe adenoma and one patient with the rare combination of hypopituitarism and sexual precocity, of as yet undefined cause.27 The physical characteristics of the entire treatment popu¬ lation as the patients entered the first 6-months therapy phase (phase 02) are illustrated in Fig. 1. (Because of little apparent difference in many of the physical characteristics at the beginning of therapy or in response to hGH therapy, various diagnostic categories are considered together for most of the data presentation. Exceptions, when noted, will be discussed.) The two youngest patients were then 2%2 and 2%2 years old; the two oldest patients were 25 %2 and 25 %2 years old and both had hGH deficiency in combination with gonadotropin deficiency only. The youngest patient with craniopharyngioma was then 3%2 years old and the oldest was 18*% 2 years old. The most frequent chronologic age (CA) at the onset of therapy in these patients was between 12 and 16 years. However, the most frequent height age (HA) then was .
Table I.Diagnostic classification, sex distribution and associated deficiencies in pituitary hormones in 151 patients with hypopituitarism due to hGH deficiency
"Total males fSee text.
=
108 (71.5%); total females
=
43(28.5%)
CMA JOURNAL/JUNE 7, 1975/VOL. 112 1303
between 3 and 6 years, all patients having a height age of 12 years or less. There was less delay in skeletal matura¬ tion or bone age (BA) than in height age: 25% of the patients had a bone age equal to or greater than 12 years. For all patients HA < BA < CA at the onset of therapy. Perinatal history A history of perinatal difficulties, including anoxia or breech delivery, has been obtained from a high percentage of patients subsequently found to have hypopituitarism.25*26 In our study population prenatal difficulties, such as toxemia and threatened abortion, were referred to in 26 cases (17%). Only two breech deliveries were recorded but there were 14 instances (9%) of complicated labour or birth injury. Apnea and cyanosis were recorded in nine cases (6%) and neonatal hypoglycemia was recorded for four patients, two of whom were subsequently found to be ACTH-deficient as well as hGH-deficient.
Pituitary deficiencies Table I also sets forth the associated deficiencies in
pituitary hormones. TSH or ACTH deficiency or both was present in 46% of all patients with idiopathic hypo¬ pituitarism. The association of TSH and hGH deficiency was twice as common as the association of ACTH and hGH deficiency. For all TSH-deficient patients levothyroxine therapy was prescribed at a dosage of 0.1 to 0.2 mg/d. For patients with documented ACTH deficiency and clinical symptoms associated with cortisol deficiency, therapy was begun with cortisone acetate by mouth at a dosage of 2.5 mg bid for patients less than 5 years old; 2.5 mg tid for those 5 to 10 years old; and 10 to 15 mg/d for those more than 10 years old. Only one patient in the entire study group was receiving cortisone replacement therapy without thyroid hormone. Three patients had ADH deficiency in association with idiopathic hGH deficiency. In the majority of our patients with idiopathic disease gonadotropin deficiency could not be assessed accurately at the time of this tabulation; however, in 18% gona¬ dotropin concentrations were normal, whereas in 16% the age data warranted the diagnosis of gonadotropin defi¬ ciency (CA > 18, BA > 15). In the organic (craniopharyngioma) group 85% of the patients were deficient in ACTH and TSH, whereas only 65% were deficient in ADH. All had been treated surgi¬ cally. Normal puberty developed or was maintained in two patients but the majority were either deficient in gonadotropins or their status was uncertain at the time. In the "other" category 8 of the 11 patients (72%) had either a deficiency of TSH or a deficiency of TSH and ACTH; one of these (with histiocytosis X) had associated ADH deficiency. Three patients had normal gonadotropin function two female siblings with familial isolated hGH deficiency and the patient with sexual precocity and hypo-
pituitarism due to an as yet undefined hypothalamic pitu¬ itary lesion.27 Response to therapy Increment in growth velocity of total population: The mean height velocity in phase 02 for all patients in the organic group was 0.78 ± 0.21 (SD) cm/mo; therefore
these patients have been included in all group analyses unless otherwise specified. A significant (P < 0.001) in¬ crease in mean height velocity was observed during all treatment phases in all patients (Figs. 2A and 2B). The greatest mean response, 0.93 ± 0.30 cm/mo, occurred in the first treatment phase (02) for patients less than 12 years old (Fig. 2A). This represented an approximate threefold increase from the pretreatment mean height velocity. Pa¬ tients more than 12 years old (Fig. 2B) achieved a similar height velocity (0.86 ± 0.29 cm/mo). No significant dif¬ ference was observed between the responses in phase 02 for patients in the two age categories (P > 0.05). In the younger patients the response was significantly decreased in each subsequent treatment phase (P < 0.005 for phases 04 and 06 v. 02), but by the 5th year of treatment (phase 10) the patients had a mean height velocity of 0.82 ± 0.26 cm/mo (Fig. 2A), which was not significantly different from that in phase 02 (P > 0.1); however, the mean height velocity in ±the off-treatment phases progressively declined, from 0.29 0.1 cm/mo in phase 01 to 0.15 ± 0.12 cm/mo in phase 09 (P < 0.005). In the older patients (Fig. 2B) 14r OControl XtSD X2SD (ZZlhGH
6 121824303642 48 54 60 Mo 0 7 8 42 27 19 13 35 69 61 51 N 91 8*° 8*4 *-* 9'° 9.2 9.0 92 9.3 9.0 8'8 -*CA ±23 ±1.8 ±2A ±1.7 ±2.1 +1.7 ±1.5 +12 ±1.6 ±1.9 ±1.7
02 03 04 05 06 07 08 09 10 FIG. 2A.Mean height velocity (cm/mo) for all patients less than 12 years old in 10 control and hGH therapy phases during 60 months of observations. N number of subjects in each phase; C/ chronologic age (mean ± SD). 01
=
=
14,
.
?
JZA
? Control XtS D IZZ hGH XtSD
ca HA
r&
>
2
MoO Years
FIG.
1.Physical characteristics of 151 patients with hypopituitarism at onset of hGH therapy. CA = chronologic age, HA height age, BA = bone age. ==
1304 CMA JOURNAL/JUNE 7, 1975/VOL. 112
N CA **A
6 82
!
12 78
1824 72
55
3036 42 54
42
485460
'*7 !ff ±2.9 %'£ 13.1 16? ±2.6 *! ±3.9 16£ ±2.4 S3.1
30 20 14 .° '*. '** *2.7 ±23 +2A
02 03 04 05
08
01
06 07
8
1*4 ±1.6
09 10
FIG. 2B.Mean height velocity (cm/mo) for all patients 12 years and older in 10 control and hGH therapy phases.
this decline in growth rate in the off-treatment phases was not readily apparent, and after phase 02 the mean growth rate diminished significantly (P < 0.005). In addition, for
patients reaching phase 10 the growth velocity had decreased significantly (P < 0.005) between phases 02 and 10 for both age groups. The mean growth velocity for phase 10 in the two age groups was not significantly different. These data thus indicate that there was a continued, although diminished, response to intermittent hGH therapy in both younger and older patients. However, the mean de¬ crease in response during treatment phases 04, 06 and 08 was significantly greater (P < 0.005) in the patients more than 12 years old when compared with the responses in the same treatment phases in the younger patients. Influence of dose and age on response: Fig. 3A indicates the 15
PHASE 02 12 YR
1.4
rh
x±so
1.2 1X> .8 .6
.4
borf*09 N CA
.10 -.19
16 20 10 8.2
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JLL 1ZL. *2£_
63
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that in phase 02 the younger patients received the largest dose. This resulted in a significantly greater (P < 0.01) mean height velocity when the dose was 0.20 to 0.29 units/kg than when it was less than 0.20 units/kg. In the patients 12 years or older the mean height velocity in¬ creased with each increase in dose, but for only the lowest (0 to 0.09 units/kg) and the highest (0.20 to 0.29 units/kg) doses was there a significant difference in mean height velocity (P = 0.01). The mean height velocities attained at the optimal dose (0.20 to 0.29 units/kg) for each age group did not differ significantly (P = 0.05). Thus, these data indicate an enhanced mean response with increasing dose and decreasing age. These data further suggest that a dosage of 0.20 to 0.29 units/kg three times a week is optimal in patients less than 12 years old, and that in patients 12 years or older a dosage of at least 0.20 to 0.29 units/kg three times a week (i.e. a larger total dose) is required to produce similar growth increments. Detailed analysis of subsequent treatment phases did not yield any additional information except to support the sug¬ gestion that mean height velocity decreased for all patients in subsequent treatment phases. In phase 04, for example (Fig. 3B), a dosage of 0.20 to 0.29 units/kg three times a week was optimal for patients less than 12 years old; the older patients again required 0.20 to 0.29 units/kg to achieve similar growth increments. Influence of other hormonal therapy: Neither other hormonal therapy (except for therapy with fluoxymesterone) nor spontaneous onset of puberty significantly slowed mean growth velocity in phases 01 and 02 (Fig. 4). After reading the recent report by Van den Brande and colleagues28 that therapy with thyroid hormone plus cor¬ tisone, in the absence of hGH therapy, produced excessive advancement of skeletal age in children with hypopituitar¬ ism, we analysed similar variables in our patients. Table II illustrates the mean increments in chronologic age (A CA), height age (A HA) and bone age (A BA) during
FIG. 3A.Influence of dosage (units/kg three times per week) and age on height velocity (cm/mo) in phase 02. Differences in height velocity were significant for A v. C (P = 0.01), A v. D (P = 0.025), A v. F (P < 0.025) and F v. H (P 0.01). All other differences were not significant, including C v. H (P = 0.05). =
? T4 Q T4+E 12i
X (Total Group .X (Total Group
¦ t4+e+p
12)
21 PHASE
01
19
10
END
8
02
FIG. 4.Influence of other hormonal treatment on observed response to hGH therapy. T4 = levothyroxine; E = cortisone; P Pitressin (vasopressin); END = endogenous puberty. During hGH therapy (phase 02) no significant influence on mean growth velocity due to these additional hormones was observed. Patients with endogenous puberty grew at a faster rate before hGH therapy, but once therapy was =
FIG. 3B.Influence of dosage (units/kg three times per week) and age on height velocity (cm/mo) in phase 04. Differences in height velocity were significant for A v. C (P < 0.005), E v. G (P
Summary: The Medical Research Council of Canada has initiated human growth hormone (hGH) therapy in 151 patients with documented complete hGH deficiency that was idiopathic in 76% of cases, secondary to craniopharyngioma (organic) ki 17% and of varied cause in 7%. Approximately 50% of the patients with idiopathic disease had isolated hGH deficiency; during therapy thyroid deficiency developed in five patients and cortisol deficiency in three. A similar increase in mean height velocity occurred in the first treatment phase for patients less than 12 years old (0.93 ± 0.30 cm/mo) and those 12 years and older (0.86 ± 0.29 cm/mo). Although subsequent courses of hGH therapy yielded significantly diminished response in both age groups, this diminution was not progressive: the height velocity of the younger patients returned to 0.82 ± 0.26 cm/mo in the fifth therapy phase. The mean height velocity attained at the optimal dosage (0.20 to 0.29 units/kg three times per week) for each age group did not differ significantly. Despite therapy being carried out for only 6 months of the year, normal increment ratios for height age and bone age against chronologic age were observed in the patients with idiopathic disease. ln only four patients did treatment failure occur, and three of these were more than 20 years old. The addition of fluoxymesterone (10 mg/d) to the hGH therapeutic regimen (15 units/wk), when diminished response to hGH alone became evident, promoted an enhanced growth response in 9 of 11 older patients. These data indicate that age of the patient and dosage of hGH, but not diagnostic category, were important influences on the response to therapy. Younger patients responded best and maintained a higher mean growth velocity than older patients during intermittent hGH
therapy.
From the departments of pediatrics* and medicine J McGill University, Montreal; department of physiology,t University of Manitoba, Winnipeg; department of pediatrics,| Hospital for Sick Children, Toronto; and department of endocrinology,! Hdpital Sainte Justine, Montreal flCurrent address: Suite 310, 350 Parnassus Ave., San Francisco, CA 94117, USA Supported by Medical Research Council of Canada grant no. MA 2525 Reprint requests to: Dr. H. Friesen, Professor and head, Department of physiology, University of Manitoba, 770 Bannantyne Ave., Winnipeg, Man. R3E 0W3
Resume: Le ConseH de recherches medicales du Canada a utilise I'hormone de croissance humaine (hGH) pour traiter 151 malades souffrant d'une insuffisance complete en hGH parfaitement prouvee. Cette deficience etait idiopathique dans 76% des cas, secondaire a un craniopharyngiome (d'origine organique) dans 17% des cas et relevait de causes diverses chez 7%. Pres de 50% des malades dont la pathologie etait de nature idiopathique presentaient une insuffisance isol6e en hGH; au cours de traitement on a note une insuffisance thyroidienne chez cinq malades et une insuffisance en hydrocortisone chez trois autres. Une augmentation similaire dans la vitesse de croissance moyenne a ete cortstat6e durant la premiere phase therapeutique tant chez les malades de moins de 12 ans (0.93 ± 0.30 cm/mo) que chez ceux Sges de 12 ans et plus (0.86 ± 0.29 cm/mo). Les s6ances therapeutiques de hGH subsequentes ont abouti a une diminution notable de la reaction clinique dans les deux groupes d'Sge, mais cette diminution n'a pas ete progressive: la vitesse de croissance de la taille des jeunes malades est revenue a 0.82 ± 0.26 cm/mo durant la cinquieme phase du traitement. La vitesse moyenne de croissance obtenue dans chaque groupe d'age avec la posologie optimale (0.20 a 0.29 unites/kg trois fois par semaine) ne differait pas significativement. En depit du fait que le traitement n'ait ete appliqu6 que durant 6 mois chaque annee, les rapports de I'augmentation normale pour I'age suivant la taille et pour Idge osseux, par rapport a I'dge chronologique, ont ete constates chez les malades souffrant de la maladie idiopathique. Le traitement n'a echoue que chez quatre malades et trois d'entre eux avaient plus de 20 ans. Quand la diminution de la reaction clinique au seul traitement avec la hGH devenait evidente, l'addition de fluoxymesterone (10 mg/d) au traitement a la hGH (15 unites/semaine), a permis d'obtenir une amelioration de la reaction de croissance chez 9 malades Sges sur 11. Ces donnees indiquent bien que I'Sge du malade et la posologie de hGH mais non la categorie diagnostique, sont les facteurs qui exercent une influence importante sur les resultats therapeutiques. Au cours d'un traitement intermittent a la hGH ce sont les jeunes malades qui ont le mieux reagi et qui ont pu maintenir un rythme de croissance plus eleve que les malades plus ages.
CMA JOURNAL/JUNE 7, 1975/VOL. 112 1301
Numerous studies have now documented that children de¬ ficient in growth hormone will respond to the administra¬ tion of low doses of human growth hormone (hGH) with an increase in linear growth velocity.1"8 Many of these studies have suffered from various defects, the most notable of which include small numbers of patients studied for an insufficient length of time, variability in the extraction procedure and source (embalmed v. nonembalmed) of hGH and a multiplicity of study design. As a result it has been difficult to answer such questions as (a) What is the best selection procedure for patients likely to benefit from hGH therapy? and (b) How is the influence of such factors as age of the patient, skeletal maturation, dosage of hGH, and associated therapy (namely cortisone, levothyroxine or androgen therapy) on the observed response best deter¬ mined? For these reasons the Medical Research Council of Canada agreed to undertake a collaborative therapeutic trial of hGH in Canada on a national scale with rigid criteria for patient acceptance into the study, a uniform and clearly defined standard protocol for all patients, and compilation of all obtained data in one central facility for statistical evaluation. This report documents the results obtained during the first 5 years of this study. Material and methods To date 151 patients have entered our study. Most university medical faculties in Canada have an assigned physician-coordinator who submits the records of potential can¬ didates to a central selection committee. Once the patient is approved for therapy the same coordinator then directs the hGH therapy for the patient at a local level. Anthropometric, clinical, radiographic and biochemical data are col¬ lected every 6 months on all patients and forwarded to the central facility at the University of Manitoba (previously at McGill University) for incorporation into a computer tape program. The first group of patients began therapy in January 1968 and this review includes data available as of July 1973.
Diagnosis Pituitary function: Only patients with documented hGH deficiency were studied; those with all other categories of hypopituitarism, including Turner's syndrome, delayed growth and adolescence, and intrauterine growth retarda¬ tion, were excluded. HGH deficiency has been defined as a failure of serum hGH concentration, as determined by radioimmunoassay, to respond to at least two provocative stimuli: insulininduced hypoglycemia and arginine hydrochloride infusion. While other provocative stimuli, such as levodopa, glu¬ cagon, tolbutamide plus glucagon, exercise and sleep re¬ lease,9'10 have been shown to induce hGH release, testing with them was not required for inclusion in this study. All patients were required to be chemically euthyroid at the time of the hGH stimulation studies. If severe constitu¬ tionai delay with impaired release of hGH due to a deficiency in sex hormones was suspected, studies were
performed after pretreatment with either estrogens or androgens.11'14 HGH was measured by radioimmunoassay15 at the central facility for all patients, thus excluding interlaboratory assay differences. If values did not exceed 5.0 ng/ml at any time during any of the stimulation tests the patient was considered a potentially suitable candidate for hGH therapy, provided the additional criteria indicated below were also met. Additional assessment of pituitary function included the following: 1. Status of thyroid-stimulating hormone (TSH; thyro¬ tropin). Serum thyroxine estimation more recently and protein-bound iodine estimation originally; radioactive 1302 CMA JOURNAL/JUNE 7,
1975/VOL. 112
iodine uptake before and, in some cases, after TSH stimula¬ tion; response of TSH to thyrotropin-releasing hormone in selected cases; and serum TSH and thyroid antibody de¬ terminations, when indicated, were performed. Interpreta¬
was based on the laboratory criteria in the diagnostic centre where the patient was evaluated. 2. Status of adrenocorticotropic hormone (ACTH). Originally the urinary corticoid response to oral metyrapone was used to determine endogenous ACTH status. However, more recently, documentation of morning and evening serum cortisol values and serum cortisol responses to insulin-induced hypoglycemia by competitive protein-binding assay have been used to document indirectly ACTH de¬ ficiency.16,17 If the increase in serum cortisol value was less than twofold, ACTH stimulation to exclude primary adre¬ nal failure has been carried out in most instances. 3. Gonadotropin status. All patients were classified from clinical photographs according to the stages of Marshall and Tanner.18,19 Serum concentrations of luteinizing and follicle-stimulating hormones are being determined by ra¬ dioimmunoassay in most of the study population and the results will be reported separately by C. Faiman and J.S.D. Winter. 4. Prolactin status. Serum prolactin was determined by radioimmunoassay in all patients and a preliminary report has appeared.20 5. Posterior pituitary status. Determination of urinary concentrating ability after an overnight fast or prolonged dehydration was used to assess the status of antidiuretic hormone (ADH) in the absence of clinical diabetes insipidus. Additional criteria for patient selection: Twice annually the patient-selection committee met to select candidates for the study. Major criteria included absolute hGH deficiency (on the basis of a lack of significant hGH response to both insulin and arginine tests), a height that was at least three standard deviations and usually more than four standard deviations below the normal mean for age, an interval growth rate for 1 year of less than 0.40 cm/mo, and skel¬ etal maturation or bone age, estimated according to the method of Greulich and Pyle,21 that was delayed at least two standard deviations below the normal mean for age. Radiographs of the sella turcica were obtained on all patients initially and on patients with craniopharyngioma annually thereafter. "Height age" was determined according to the method of Wilkins.22 Most patients were prepubertal (Tanner stage I) before inclusion in the study. However, certain exceptions were made for patients considered to have limited growth potential because of rapidly advancing spontaneous puberty at the time of initial consideration. (These exceptions will be dealt with separately below.) Chromosome determinations on buccal smears were con¬ sidered essential for all female patients to exclude those with Turner's syndrome and its variants. Patients receiving sex steroids before consideration were not accepted into the study. Treatment protocol In all patients there was a pretreatment period of at least 6 months (phase 01), during which time interval growth determinations, complete assessment of pituitary function, assessment of skeletal maturation and other pertinent studies were performed. Each patient then began 6 months of hGH therapy followed by 6 months with¬ out hGH therapy. The 6-months alternating schedule was continued as long as an accelerated growth velocity continued. Patients were arbitrarily assigned to a dosage regimen of either 2 or 5 units given by intramuscular in¬ jection three times per week, for a total dose of 6 or 15 units/wk. If growth velocity was insufficient (less than 0.35 cm/mo) with the smaller dose the patient was
tion of results
given
the larger dose during his next course of therapy. Patients with a diminished response to the larger dose were then included in an additional protocol, which added 10 mg/d of fluoxymesterone (Halotestin) to the 15 units/wk of hGH. This combined therapy followed a 6-months period of treatment with fluoxymesterone alone. This latter treat¬ ment group consisted of the oldest patients, including eight males and three females to date. Treatment in this group was continued, if successful, until satisfactory height was attained, growth ceased because of advanced skeletal ma¬ turation, indicative of epiphyseal fusion, or the patient wished to be removed from the study. Preparation of hGH HGH was prepared, according to a modification of the method of Raben,23 from human pituitary glands removed at autopsy (under the auspices of the Committee on Human Pituitary Hormones, sponsored by the Medical Research Council of Canada). This program yields approximately 10 000 pituitary glands per year, which is insufficient to maintain all patients requiring growth hormone in Canada on continuous hGH therapy. In part this has necessitated the alternating 6-months therapy protocol. The potency of the various batches of hGH used during the study varied from 0.68 to 1.60 IU/mg, as determined by bioassay (the 10-day increase in body weight in hypophysectomized rats).* The hGH to be administered was kept in vials containing 10 IU of the hormone. Determination of antibodies to hGH and prolactin The development of antibodies to hGH was assessed every 6 months on all patients during the study in the laboratory that performed the hGH radioimmunoassays. All patient sera were screened at a dilution of 1:10 for the presence of antibody binding to hGH labelled with radio¬ active iodine, after incubation at 4°C for 24 hours and separation by charcoal. All sera positive at this original dilution were then further diluted until levels of binding similar to those of control sera at a 1:10 dilution were achieved. This dilution was then used to approximate the specific binding of the hGH tracer by that patient's serum. No attempts were made to determine actual binding capa¬ city for hGH in patients with demonstrable antibodies. Autoantibodies to human prolactin were determined in an identical manner using human prolactin labelled with radioactive iodine. Assessment of growth response At the beginning and end of each 6-months therapy period the patient's height, weight, skeletal maturation (ac¬ cording to the Greulich and Pyle atlas21) and sexual stage was recorded, a clinical photograph was obtained and serum was screened for antibodies to hGH. During the period of therapy the height was measured every 2 months by the physician-coordinator. All patient data were forwarded to the central facility and entered in the computer tape program for statistical analysis. Growth velocity (cm/mo) was determined during each 6-months phase. The dose of hGH received was calculated in terms of the units per kilogram given three times per week; because of the great changes in weight during therapy in many patients, a mean of the starting and ending weight for each treat¬ ment phase was used to perform this calculation. Initial observations in this study and by other groups suggested that older patients with hGH deficiency respond less well during therapy than younger patients; therefore, the data were adjusted so that calculations were performed sepa¬ rately for all patients less than 12 years of age and all patients 12 years and older. Thus, increments in growth 'Endocrine Laboratories of Madison, Inc,
Madison, Wisconsin.
velocity
in relation to both age and units/kg of hGH administered could be determined. Other variables that possibly affect the observed growth response, including additional hormone therapy (levothyroxine and cortisone) and spontaneous or induced puberty, were assessed for their influence on each diagnostic cate¬ gory of patients. The influence of these variables on ob¬ served growth velocity as well as on the subsequently de¬ rived increment ratios for height age (A HA), bone age (A BA) and chronologic age (A CA) was also assessed, as was the influence of the development of antibodies to hGH on growth velocity. Statistical analysis All statistical analyses were performed using the Student's / test.
Results
Physical data As indicated in Table
I, the distribution of
causes
of
hypopituitarism in the patients included in this trial is similar to that described for most reported groups of pa¬ tients with hypopituitarism;1"8'24'26 that is, 76% of the pa¬ tients were considered to have idiopathic disease, and males predominated in this category (2.7:1). About 17% of our patients had organic disease (craniopharyngioma) and about 7% were placed in the "other" diagnostic category five patients with familial idiopathic hypopituitarism (in¬ cluding two female siblings), three patients with disease of traumatic origin, one patient with histiocytosis X, one patient with a chromophobe adenoma and one patient with the rare combination of hypopituitarism and sexual precocity, of as yet undefined cause.27 The physical characteristics of the entire treatment popu¬ lation as the patients entered the first 6-months therapy phase (phase 02) are illustrated in Fig. 1. (Because of little apparent difference in many of the physical characteristics at the beginning of therapy or in response to hGH therapy, various diagnostic categories are considered together for most of the data presentation. Exceptions, when noted, will be discussed.) The two youngest patients were then 2%2 and 2%2 years old; the two oldest patients were 25 %2 and 25 %2 years old and both had hGH deficiency in combination with gonadotropin deficiency only. The youngest patient with craniopharyngioma was then 3%2 years old and the oldest was 18*% 2 years old. The most frequent chronologic age (CA) at the onset of therapy in these patients was between 12 and 16 years. However, the most frequent height age (HA) then was .
Table I.Diagnostic classification, sex distribution and associated deficiencies in pituitary hormones in 151 patients with hypopituitarism due to hGH deficiency
"Total males fSee text.
=
108 (71.5%); total females
=
43(28.5%)
CMA JOURNAL/JUNE 7, 1975/VOL. 112 1303
between 3 and 6 years, all patients having a height age of 12 years or less. There was less delay in skeletal matura¬ tion or bone age (BA) than in height age: 25% of the patients had a bone age equal to or greater than 12 years. For all patients HA < BA < CA at the onset of therapy. Perinatal history A history of perinatal difficulties, including anoxia or breech delivery, has been obtained from a high percentage of patients subsequently found to have hypopituitarism.25*26 In our study population prenatal difficulties, such as toxemia and threatened abortion, were referred to in 26 cases (17%). Only two breech deliveries were recorded but there were 14 instances (9%) of complicated labour or birth injury. Apnea and cyanosis were recorded in nine cases (6%) and neonatal hypoglycemia was recorded for four patients, two of whom were subsequently found to be ACTH-deficient as well as hGH-deficient.
Pituitary deficiencies Table I also sets forth the associated deficiencies in
pituitary hormones. TSH or ACTH deficiency or both was present in 46% of all patients with idiopathic hypo¬ pituitarism. The association of TSH and hGH deficiency was twice as common as the association of ACTH and hGH deficiency. For all TSH-deficient patients levothyroxine therapy was prescribed at a dosage of 0.1 to 0.2 mg/d. For patients with documented ACTH deficiency and clinical symptoms associated with cortisol deficiency, therapy was begun with cortisone acetate by mouth at a dosage of 2.5 mg bid for patients less than 5 years old; 2.5 mg tid for those 5 to 10 years old; and 10 to 15 mg/d for those more than 10 years old. Only one patient in the entire study group was receiving cortisone replacement therapy without thyroid hormone. Three patients had ADH deficiency in association with idiopathic hGH deficiency. In the majority of our patients with idiopathic disease gonadotropin deficiency could not be assessed accurately at the time of this tabulation; however, in 18% gona¬ dotropin concentrations were normal, whereas in 16% the age data warranted the diagnosis of gonadotropin defi¬ ciency (CA > 18, BA > 15). In the organic (craniopharyngioma) group 85% of the patients were deficient in ACTH and TSH, whereas only 65% were deficient in ADH. All had been treated surgi¬ cally. Normal puberty developed or was maintained in two patients but the majority were either deficient in gonadotropins or their status was uncertain at the time. In the "other" category 8 of the 11 patients (72%) had either a deficiency of TSH or a deficiency of TSH and ACTH; one of these (with histiocytosis X) had associated ADH deficiency. Three patients had normal gonadotropin function two female siblings with familial isolated hGH deficiency and the patient with sexual precocity and hypo-
pituitarism due to an as yet undefined hypothalamic pitu¬ itary lesion.27 Response to therapy Increment in growth velocity of total population: The mean height velocity in phase 02 for all patients in the organic group was 0.78 ± 0.21 (SD) cm/mo; therefore
these patients have been included in all group analyses unless otherwise specified. A significant (P < 0.001) in¬ crease in mean height velocity was observed during all treatment phases in all patients (Figs. 2A and 2B). The greatest mean response, 0.93 ± 0.30 cm/mo, occurred in the first treatment phase (02) for patients less than 12 years old (Fig. 2A). This represented an approximate threefold increase from the pretreatment mean height velocity. Pa¬ tients more than 12 years old (Fig. 2B) achieved a similar height velocity (0.86 ± 0.29 cm/mo). No significant dif¬ ference was observed between the responses in phase 02 for patients in the two age categories (P > 0.05). In the younger patients the response was significantly decreased in each subsequent treatment phase (P < 0.005 for phases 04 and 06 v. 02), but by the 5th year of treatment (phase 10) the patients had a mean height velocity of 0.82 ± 0.26 cm/mo (Fig. 2A), which was not significantly different from that in phase 02 (P > 0.1); however, the mean height velocity in ±the off-treatment phases progressively declined, from 0.29 0.1 cm/mo in phase 01 to 0.15 ± 0.12 cm/mo in phase 09 (P < 0.005). In the older patients (Fig. 2B) 14r OControl XtSD X2SD (ZZlhGH
6 121824303642 48 54 60 Mo 0 7 8 42 27 19 13 35 69 61 51 N 91 8*° 8*4 *-* 9'° 9.2 9.0 92 9.3 9.0 8'8 -*CA ±23 ±1.8 ±2A ±1.7 ±2.1 +1.7 ±1.5 +12 ±1.6 ±1.9 ±1.7
02 03 04 05 06 07 08 09 10 FIG. 2A.Mean height velocity (cm/mo) for all patients less than 12 years old in 10 control and hGH therapy phases during 60 months of observations. N number of subjects in each phase; C/ chronologic age (mean ± SD). 01
=
=
14,
.
?
JZA
? Control XtS D IZZ hGH XtSD
ca HA
r&
>
2
MoO Years
FIG.
1.Physical characteristics of 151 patients with hypopituitarism at onset of hGH therapy. CA = chronologic age, HA height age, BA = bone age. ==
1304 CMA JOURNAL/JUNE 7, 1975/VOL. 112
N CA **A
6 82
!
12 78
1824 72
55
3036 42 54
42
485460
'*7 !ff ±2.9 %'£ 13.1 16? ±2.6 *! ±3.9 16£ ±2.4 S3.1
30 20 14 .° '*. '** *2.7 ±23 +2A
02 03 04 05
08
01
06 07
8
1*4 ±1.6
09 10
FIG. 2B.Mean height velocity (cm/mo) for all patients 12 years and older in 10 control and hGH therapy phases.
this decline in growth rate in the off-treatment phases was not readily apparent, and after phase 02 the mean growth rate diminished significantly (P < 0.005). In addition, for
patients reaching phase 10 the growth velocity had decreased significantly (P < 0.005) between phases 02 and 10 for both age groups. The mean growth velocity for phase 10 in the two age groups was not significantly different. These data thus indicate that there was a continued, although diminished, response to intermittent hGH therapy in both younger and older patients. However, the mean de¬ crease in response during treatment phases 04, 06 and 08 was significantly greater (P < 0.005) in the patients more than 12 years old when compared with the responses in the same treatment phases in the younger patients. Influence of dose and age on response: Fig. 3A indicates the 15
PHASE 02 12 YR
1.4
rh
x±so
1.2 1X> .8 .6
.4
borf*09 N CA
.10 -.19
16 20 10 8.2
.20 .30 .40 -.29 -.39 -60 7.0
JLL 1ZL. *2£_
63
12.Q
5.7
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.00
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that in phase 02 the younger patients received the largest dose. This resulted in a significantly greater (P < 0.01) mean height velocity when the dose was 0.20 to 0.29 units/kg than when it was less than 0.20 units/kg. In the patients 12 years or older the mean height velocity in¬ creased with each increase in dose, but for only the lowest (0 to 0.09 units/kg) and the highest (0.20 to 0.29 units/kg) doses was there a significant difference in mean height velocity (P = 0.01). The mean height velocities attained at the optimal dose (0.20 to 0.29 units/kg) for each age group did not differ significantly (P = 0.05). Thus, these data indicate an enhanced mean response with increasing dose and decreasing age. These data further suggest that a dosage of 0.20 to 0.29 units/kg three times a week is optimal in patients less than 12 years old, and that in patients 12 years or older a dosage of at least 0.20 to 0.29 units/kg three times a week (i.e. a larger total dose) is required to produce similar growth increments. Detailed analysis of subsequent treatment phases did not yield any additional information except to support the sug¬ gestion that mean height velocity decreased for all patients in subsequent treatment phases. In phase 04, for example (Fig. 3B), a dosage of 0.20 to 0.29 units/kg three times a week was optimal for patients less than 12 years old; the older patients again required 0.20 to 0.29 units/kg to achieve similar growth increments. Influence of other hormonal therapy: Neither other hormonal therapy (except for therapy with fluoxymesterone) nor spontaneous onset of puberty significantly slowed mean growth velocity in phases 01 and 02 (Fig. 4). After reading the recent report by Van den Brande and colleagues28 that therapy with thyroid hormone plus cor¬ tisone, in the absence of hGH therapy, produced excessive advancement of skeletal age in children with hypopituitar¬ ism, we analysed similar variables in our patients. Table II illustrates the mean increments in chronologic age (A CA), height age (A HA) and bone age (A BA) during
FIG. 3A.Influence of dosage (units/kg three times per week) and age on height velocity (cm/mo) in phase 02. Differences in height velocity were significant for A v. C (P = 0.01), A v. D (P = 0.025), A v. F (P < 0.025) and F v. H (P 0.01). All other differences were not significant, including C v. H (P = 0.05). =
? T4 Q T4+E 12i
X (Total Group .X (Total Group
¦ t4+e+p
12)
21 PHASE
01
19
10
END
8
02
FIG. 4.Influence of other hormonal treatment on observed response to hGH therapy. T4 = levothyroxine; E = cortisone; P Pitressin (vasopressin); END = endogenous puberty. During hGH therapy (phase 02) no significant influence on mean growth velocity due to these additional hormones was observed. Patients with endogenous puberty grew at a faster rate before hGH therapy, but once therapy was =
FIG. 3B.Influence of dosage (units/kg three times per week) and age on height velocity (cm/mo) in phase 04. Differences in height velocity were significant for A v. C (P < 0.005), E v. G (P
