Biochemical Evaluation of Adrenal Dysfunction: The Laboratory Perspective
KAREN SNOW, Ph.D., Molecular Genetics Laboratory; NAI-SIANG JIANG, Ph.D., PAl C. KAO, Ph.D., Section of Clinical Biochemistry; BERND W. SCHEITHAUER, M.D., Section of Surgical Pathology
In this study, we reviewed the diagnostic efficiency of laboratory tests that are performed for assessment of patients with Cushing's syndrome or adrenal insufficiency. Baseline laboratory data from patients subsequently diagnosed with adrenal dysfunction were analyzed for tests performed between 1987 and 1989 at our institution. Results were analyzed for 36 patients diagnosed with pituitarydependent Cushing's syndrome, 15 with ectopic Cushing's syndrome, 12 with adrenal-dependent Cushing's syndrome, 20 with primary adrenal insufficiency, and 7 with secondary adrenal insufficiency. Tests reviewed were plasma cortisol, plasma corticotropin, urinary free cortisol, urinary 17ketosteroids, urinary ketogenic steroids, low-dose and high-dose dexamethasone suppression, and metyrapone stimulation. Our findings suggest that a substantial proportion of diagnoses could be based on the results of three tests-plasma corticotropin, plasma cortisol, and urinary free cortisol. We present a nomogram that combines the results of plasma corticotropin and plasma cortisol testing to enhance the diagnostic efficiency of these tests.
Disorders of the adrenal cortex include adrenal hyperfunction (Cushing's syndrome) and adrenal hypofunction. Cushing's syndrome may be due to a pituitary adenoma (Cushing's disease), ectopic adrenocorticotropic hormone (ACTH or corticotropin)- or corticotropin releasing hormone-producing tumors (or both), adrenocortical tumors or hyperplasia, or excess of exogenous glucocorticoid.I-' Causes of adrenal hypofunction include primary failure of the adrenal glands (Addison's disease) and secondary adrenalinsufficiency from deficient production of corticotropin.' Addison's disease can be due to destruction of adrenal tissue by hemorrhage, infection, neoplastic infiltrates, ketoconazole therapy, or autoimmunity. In contrast, corticotropin insufficiency has many potential causes but probably occurs most commonly after sudden withdrawal of corticosteroid therapy, after head trauma, or after a surgical procedure on the pituitary gland. Acute adrenal insufficiency (addisonian crisis), a potentially fatal condition, is usually associated with fever, nausea, vomiting, hypoglycemia, and shock. Address reprint requests to Dr. N.-S. Jiang, Section of Clinical Biochemistry, Mayo Clinic, Rochester, MN 55905. MayoClinProc 67:1055-1065,1992
A diagnosis of adrenal hyperfunction or hypofunction is based on clinical, laboratory, and radiologic findings.>' While recognizing the importance of clinical information, we have focused the current study on the diagnostic value of various laboratory tests. Because of recent technical improvements in laboratory tests and also expansion of test repertoire, the applicability of tests to the diagnosis and evaluation of adrenocortical function may have changed. In this report, we review laboratory data obtained between 1987 and 1989, inclusive, for patients diagnosed with adrenocortical dysfunction. We attempt to identify the most efficient tests for establishing the diagnosis of Cushing's syndrome and of adrenal insufficiency.
DATABASE We reviewed the medical records of all patients who underwent a workup for Cushing's syndrome or adrenal insufficiency between 1987 and 1989 at the Mayo Clinic; thus, only laboratory data obtained by currently used procedures were entered in this study. The data base for each of the disease categories reviewed is summarized in Table 1. 1055
Mayo Clin Proc, November 1992, Vol 67
1056 BIOCHEMICAL EVALUATION OF ADRENAL DYSFUNCTION
Table 1. -Summary of Available Data on Mayo Patients Who Underwent Workup for Cushing's Syndrome or Adrenal Insufficiency Between 1987 and 1989
Diagnosed disease
Total no. of patients
Male Age range (yr) No.
Female Age range (yr) No.
Comments*
Pituitary-dependent Cushing's (Cushing's disease)
36
9
I I-59
27
18-72
Pituitary adenoma evident on CT or MRI (18) Pituitary adenoma detected by histopathologic examination and corticotropin immunostain positive (30) Pituitary adenoma with negative immunostain (1) Hypocortisolism after hypophysectomy (29) Cortisol within normal range after hypophysectomy (7)
Ectopic Cushing's
15
5
26-60
10
26-70
Carcinoid tumor (5) Islet cell carcinoma (l) Neuroendocrine carcinoma (1) Medullary thyroid carcinoma (1) Pulmonary nodules present (1) Liver masses but no malignant lesion identified (1) Persistent Cushing's; pituitary or ectopic source not located (5)
Adrenal-dependent Cushing's
12
38
11
16-68
Adrenal tumor detected by CT and histopathologic examination (12), including adenoma in 10, carcinoma in 1, and bilateral macronodular adrenal hyperplasia in 1
Primary adrenal insufficiency (Addison's disease)
20
11
6-61
9
21-61
Previously diagnosed and treated (5); treatment stopped before biochemical testing Newly diagnosed (15), including multiglandular deficiency in 4 and adrenal hemorrhage, tuberculosis of adrenal gland, and adrenoleukodystrophy in I each
7
3
29-73
4
30-70
Isolated corticotropin insufficiency (6) Pituitary insufficiency after pituitary operation (1)
Secondary adrenal insufficiency *Values in parentheses
=number of patients.
CT = computed tomography; MRI = magnetic resonance imaging.
FINDINGS The laboratory data abstracted from the medical records of the patients and the measurements derived from 22 healthy control subjects were summarized (Table 1 and Fig. 1). Control data were collected for the same period as patient data. Measurements used in the study were obtained before any provocative testing, and a.m. plasma cortisol and a.m. corticotropin values were from the same date for each patient and control subject. Plasma Cortisol.-Normal production of corticotropin-and, therefore, synthesis and secretion of cortisolexhibits a diurnal variation, which can be overcome by various stress factors that result in neural stimulation. Cortisol in the circulation is predominantly bound to protein, 75% to cortisol-binding globulin and 15% to albumin; only 10% is not bound to protein and thus is biologically active. The Mayo Clinic laboratory test for cortisol is a radioimmunoassay that is performed without prior preparation of the
plasma sample. Thus, the assay measures total plasma cortisol and detects changes in cortisol levels that result from pregnancy or estrogen therapy (which increases cortisolbinding globulin) and proteinuria (which decreases cortisolbinding proteins). Although the increase in plasma cortisol in Cushing's syndrome and its decrease in adrenal insufficiency account for many clinical features associated with these disorders, simply measuring plasma cortisol is insufficiently sensitive for diagnosing Cushing's syndrome. This finding has been reported previously'? and was also apparent in the current study (Fig. 1 A and B). For example, among a.m. cortisol measurements obtained from patients with pituitary-dependent, ectopic, and adrenal-dependent Cushing's syndrome, values within the reference levels were obtained from 13 of 34, 1 of 15, and 9 of 12 patients, respectively. In addition, p.m. cortisol values within the reference range were obtained in 2 of 31, 0 of 14, and 3 of 12 patients with pituitary-
Mayo Clin Proc, November 1992,Vol 67
BIOCHEMICAL EVALUATION OF ADRENAL DYSFUNCTION
140
140
120
....I "0
en
::i.
"0 til
'1:
100
80
0
E
40
oj
20
•
"0
1:
60
E
40
0
'.
!JI~
o
ci
Normal
Pituitary Cushing's
Ectopic Cushing's
Adrenal 1° 2° Cushing's insufficiency insufficiency
10,000
~
u
1,000
100
~
10
Ectopic
Pituitary Cushing's
CUshing's
Adrenal Cushing's
2"
l'
insufficiency insufficiency
1
D
140
100
~
80
..,
01
E
eri
i1
60 40 20 0
E
I
Pituitary Cushing's
.c.., enE
0
C\l
•
0
:
" -1-1 cP
-
0
Pituitary Cushing's
• •
• -
'8 0
0 0 0
-o-
Ectopic Cushing's
eri
•
lo::: ~
0
=-t
Adrenal Cushing's
~
- -
"-0.. l'
insufficiency
- -
•
~-'P- - !- -!- - - - - -
••
I
•
I
i=
E
~----------------~----.~
Prtuitary Cushing's
2' insufficiency
Ectopic CUshing's
-
Adrenal Cushing's
••
I' insufficiency
•
2" insufficiency
• Male o Female 0
50
40 30 20
0
F
•
1° 2" insufficiency insufficiency
60
10
~
Adrenal Cushing's
__
••
70
• Male o Female
Ectopic Cushing's
.
80
120
... s:
-.-••• • Au!.---:;---~f ----------___,-_
~ E
::l
Normal
Normal
B
.c
1
.:0- - 10
0
10,000 ~
C
..
· ~I
20
.:1':"_ - - - •
• •
0
A
80
til
··il ---~•':.' ----r:i--• :..:----I:r --.- ----1.1
100
:::I..
·
','
o
en
..••
80
•
120
....I "0
1057
• • •
:f Pituitary Cushing's
• • 8J
-
•
0
"'IT'
l6>
..0-
Ectopic
Cushing's
0
-r
-
-£ Adrenal
Cushing's
- 'ii'
-0
I' insufficiency
- -'71" 2" insufficiency
Fig. 1. Results of biochemical testing in adrenal hyperfunction or hypofunction. Laboratory values are from 22 healthy subjects and from 36 patients with pituitary-dependent Cushing's syndrome, 15 with ectopic Cushing's syndrome, 12 with adrenal-dependent Cushing's syndrome, 20 with primary adrenal insufficiency, and 7 with secondary adrenal insufficiency. For C, reference range values are below the brokenline; for all other parts of Figure 1, reference range is between broken lines. Some patients did not have all tests performed, and some patients had two baseline measurements for a single analyte. A, a.m. cortisol. B, p.m. cortisol. C, Adrenocorticotropic hormone (ACTH or corticotropin). D, Urinary free cortisol (UFC). E, Urinary ketogenic steroids (KGS). F, Urinary 17-ketosteroids (17-KS).
dependent, ectopic, and adrenal-dependent Cushing's syndrome, respectively. Lack of diurnal variation in production of cortisol in Cushing's syndrome is reflected by the a.m. cortisol/p.m. cortisol ratio in these subjects (Table 2). Some overlap is evident, however, between ratios calculated for
normal subjects and those for patients with Cushing's syndrome. Indeed, lack of diurnal variation of cortisol levels is not a specific marker for Cushing's syndrome because numerous stress factors, including illness and hospitalization, can affect the results. Measurement of plasma cortisol in
1058
BIOCHEMICAL EVALUATION OF ADRENAL DYSFUNCTION
Mayo Clln Proc, November 1992, Vol 67
Table 2.-Summary of Laboratory Data for Healthy Control Subjects and Study Patients With Various Types of Adrenal Dysfunction* Healthy subjects (N = 22)
Pituitarydependent Cushing's (N = 36)
Ectopic Cushing's (N = 15)
Adrenaldependent Cushing's (N = 12)
Primary adrenal insufficiency (N =20)
Secondary adrenal insufficiency (N = 7)
a.m. cortisol (~g/dl) Range Mean (n) SO
9-25 14.4 (22) 4.8
12-42 27.5 (37) 7.7
25-130 49.1 (19) 24.8
13-34 22.2 (12) 5.7
KAREN SNOW, Ph.D., Molecular Genetics Laboratory; NAI-SIANG JIANG, Ph.D., PAl C. KAO, Ph.D., Section of Clinical Biochemistry; BERND W. SCHEITHAUER, M.D., Section of Surgical Pathology
In this study, we reviewed the diagnostic efficiency of laboratory tests that are performed for assessment of patients with Cushing's syndrome or adrenal insufficiency. Baseline laboratory data from patients subsequently diagnosed with adrenal dysfunction were analyzed for tests performed between 1987 and 1989 at our institution. Results were analyzed for 36 patients diagnosed with pituitarydependent Cushing's syndrome, 15 with ectopic Cushing's syndrome, 12 with adrenal-dependent Cushing's syndrome, 20 with primary adrenal insufficiency, and 7 with secondary adrenal insufficiency. Tests reviewed were plasma cortisol, plasma corticotropin, urinary free cortisol, urinary 17ketosteroids, urinary ketogenic steroids, low-dose and high-dose dexamethasone suppression, and metyrapone stimulation. Our findings suggest that a substantial proportion of diagnoses could be based on the results of three tests-plasma corticotropin, plasma cortisol, and urinary free cortisol. We present a nomogram that combines the results of plasma corticotropin and plasma cortisol testing to enhance the diagnostic efficiency of these tests.
Disorders of the adrenal cortex include adrenal hyperfunction (Cushing's syndrome) and adrenal hypofunction. Cushing's syndrome may be due to a pituitary adenoma (Cushing's disease), ectopic adrenocorticotropic hormone (ACTH or corticotropin)- or corticotropin releasing hormone-producing tumors (or both), adrenocortical tumors or hyperplasia, or excess of exogenous glucocorticoid.I-' Causes of adrenal hypofunction include primary failure of the adrenal glands (Addison's disease) and secondary adrenalinsufficiency from deficient production of corticotropin.' Addison's disease can be due to destruction of adrenal tissue by hemorrhage, infection, neoplastic infiltrates, ketoconazole therapy, or autoimmunity. In contrast, corticotropin insufficiency has many potential causes but probably occurs most commonly after sudden withdrawal of corticosteroid therapy, after head trauma, or after a surgical procedure on the pituitary gland. Acute adrenal insufficiency (addisonian crisis), a potentially fatal condition, is usually associated with fever, nausea, vomiting, hypoglycemia, and shock. Address reprint requests to Dr. N.-S. Jiang, Section of Clinical Biochemistry, Mayo Clinic, Rochester, MN 55905. MayoClinProc 67:1055-1065,1992
A diagnosis of adrenal hyperfunction or hypofunction is based on clinical, laboratory, and radiologic findings.>' While recognizing the importance of clinical information, we have focused the current study on the diagnostic value of various laboratory tests. Because of recent technical improvements in laboratory tests and also expansion of test repertoire, the applicability of tests to the diagnosis and evaluation of adrenocortical function may have changed. In this report, we review laboratory data obtained between 1987 and 1989, inclusive, for patients diagnosed with adrenocortical dysfunction. We attempt to identify the most efficient tests for establishing the diagnosis of Cushing's syndrome and of adrenal insufficiency.
DATABASE We reviewed the medical records of all patients who underwent a workup for Cushing's syndrome or adrenal insufficiency between 1987 and 1989 at the Mayo Clinic; thus, only laboratory data obtained by currently used procedures were entered in this study. The data base for each of the disease categories reviewed is summarized in Table 1. 1055
Mayo Clin Proc, November 1992, Vol 67
1056 BIOCHEMICAL EVALUATION OF ADRENAL DYSFUNCTION
Table 1. -Summary of Available Data on Mayo Patients Who Underwent Workup for Cushing's Syndrome or Adrenal Insufficiency Between 1987 and 1989
Diagnosed disease
Total no. of patients
Male Age range (yr) No.
Female Age range (yr) No.
Comments*
Pituitary-dependent Cushing's (Cushing's disease)
36
9
I I-59
27
18-72
Pituitary adenoma evident on CT or MRI (18) Pituitary adenoma detected by histopathologic examination and corticotropin immunostain positive (30) Pituitary adenoma with negative immunostain (1) Hypocortisolism after hypophysectomy (29) Cortisol within normal range after hypophysectomy (7)
Ectopic Cushing's
15
5
26-60
10
26-70
Carcinoid tumor (5) Islet cell carcinoma (l) Neuroendocrine carcinoma (1) Medullary thyroid carcinoma (1) Pulmonary nodules present (1) Liver masses but no malignant lesion identified (1) Persistent Cushing's; pituitary or ectopic source not located (5)
Adrenal-dependent Cushing's
12
38
11
16-68
Adrenal tumor detected by CT and histopathologic examination (12), including adenoma in 10, carcinoma in 1, and bilateral macronodular adrenal hyperplasia in 1
Primary adrenal insufficiency (Addison's disease)
20
11
6-61
9
21-61
Previously diagnosed and treated (5); treatment stopped before biochemical testing Newly diagnosed (15), including multiglandular deficiency in 4 and adrenal hemorrhage, tuberculosis of adrenal gland, and adrenoleukodystrophy in I each
7
3
29-73
4
30-70
Isolated corticotropin insufficiency (6) Pituitary insufficiency after pituitary operation (1)
Secondary adrenal insufficiency *Values in parentheses
=number of patients.
CT = computed tomography; MRI = magnetic resonance imaging.
FINDINGS The laboratory data abstracted from the medical records of the patients and the measurements derived from 22 healthy control subjects were summarized (Table 1 and Fig. 1). Control data were collected for the same period as patient data. Measurements used in the study were obtained before any provocative testing, and a.m. plasma cortisol and a.m. corticotropin values were from the same date for each patient and control subject. Plasma Cortisol.-Normal production of corticotropin-and, therefore, synthesis and secretion of cortisolexhibits a diurnal variation, which can be overcome by various stress factors that result in neural stimulation. Cortisol in the circulation is predominantly bound to protein, 75% to cortisol-binding globulin and 15% to albumin; only 10% is not bound to protein and thus is biologically active. The Mayo Clinic laboratory test for cortisol is a radioimmunoassay that is performed without prior preparation of the
plasma sample. Thus, the assay measures total plasma cortisol and detects changes in cortisol levels that result from pregnancy or estrogen therapy (which increases cortisolbinding globulin) and proteinuria (which decreases cortisolbinding proteins). Although the increase in plasma cortisol in Cushing's syndrome and its decrease in adrenal insufficiency account for many clinical features associated with these disorders, simply measuring plasma cortisol is insufficiently sensitive for diagnosing Cushing's syndrome. This finding has been reported previously'? and was also apparent in the current study (Fig. 1 A and B). For example, among a.m. cortisol measurements obtained from patients with pituitary-dependent, ectopic, and adrenal-dependent Cushing's syndrome, values within the reference levels were obtained from 13 of 34, 1 of 15, and 9 of 12 patients, respectively. In addition, p.m. cortisol values within the reference range were obtained in 2 of 31, 0 of 14, and 3 of 12 patients with pituitary-
Mayo Clin Proc, November 1992,Vol 67
BIOCHEMICAL EVALUATION OF ADRENAL DYSFUNCTION
140
140
120
....I "0
en
::i.
"0 til
'1:
100
80
0
E
40
oj
20
•
"0
1:
60
E
40
0
'.
!JI~
o
ci
Normal
Pituitary Cushing's
Ectopic Cushing's
Adrenal 1° 2° Cushing's insufficiency insufficiency
10,000
~
u
1,000
100
~
10
Ectopic
Pituitary Cushing's
CUshing's
Adrenal Cushing's
2"
l'
insufficiency insufficiency
1
D
140
100
~
80
..,
01
E
eri
i1
60 40 20 0
E
I
Pituitary Cushing's
.c.., enE
0
C\l
•
0
:
" -1-1 cP
-
0
Pituitary Cushing's
• •
• -
'8 0
0 0 0
-o-
Ectopic Cushing's
eri
•
lo::: ~
0
=-t
Adrenal Cushing's
~
- -
"-0.. l'
insufficiency
- -
•
~-'P- - !- -!- - - - - -
••
I
•
I
i=
E
~----------------~----.~
Prtuitary Cushing's
2' insufficiency
Ectopic CUshing's
-
Adrenal Cushing's
••
I' insufficiency
•
2" insufficiency
• Male o Female 0
50
40 30 20
0
F
•
1° 2" insufficiency insufficiency
60
10
~
Adrenal Cushing's
__
••
70
• Male o Female
Ectopic Cushing's
.
80
120
... s:
-.-••• • Au!.---:;---~f ----------___,-_
~ E
::l
Normal
Normal
B
.c
1
.:0- - 10
0
10,000 ~
C
..
· ~I
20
.:1':"_ - - - •
• •
0
A
80
til
··il ---~•':.' ----r:i--• :..:----I:r --.- ----1.1
100
:::I..
·
','
o
en
..••
80
•
120
....I "0
1057
• • •
:f Pituitary Cushing's
• • 8J
-
•
0
"'IT'
l6>
..0-
Ectopic
Cushing's
0
-r
-
-£ Adrenal
Cushing's
- 'ii'
-0
I' insufficiency
- -'71" 2" insufficiency
Fig. 1. Results of biochemical testing in adrenal hyperfunction or hypofunction. Laboratory values are from 22 healthy subjects and from 36 patients with pituitary-dependent Cushing's syndrome, 15 with ectopic Cushing's syndrome, 12 with adrenal-dependent Cushing's syndrome, 20 with primary adrenal insufficiency, and 7 with secondary adrenal insufficiency. For C, reference range values are below the brokenline; for all other parts of Figure 1, reference range is between broken lines. Some patients did not have all tests performed, and some patients had two baseline measurements for a single analyte. A, a.m. cortisol. B, p.m. cortisol. C, Adrenocorticotropic hormone (ACTH or corticotropin). D, Urinary free cortisol (UFC). E, Urinary ketogenic steroids (KGS). F, Urinary 17-ketosteroids (17-KS).
dependent, ectopic, and adrenal-dependent Cushing's syndrome, respectively. Lack of diurnal variation in production of cortisol in Cushing's syndrome is reflected by the a.m. cortisol/p.m. cortisol ratio in these subjects (Table 2). Some overlap is evident, however, between ratios calculated for
normal subjects and those for patients with Cushing's syndrome. Indeed, lack of diurnal variation of cortisol levels is not a specific marker for Cushing's syndrome because numerous stress factors, including illness and hospitalization, can affect the results. Measurement of plasma cortisol in
1058
BIOCHEMICAL EVALUATION OF ADRENAL DYSFUNCTION
Mayo Clln Proc, November 1992, Vol 67
Table 2.-Summary of Laboratory Data for Healthy Control Subjects and Study Patients With Various Types of Adrenal Dysfunction* Healthy subjects (N = 22)
Pituitarydependent Cushing's (N = 36)
Ectopic Cushing's (N = 15)
Adrenaldependent Cushing's (N = 12)
Primary adrenal insufficiency (N =20)
Secondary adrenal insufficiency (N = 7)
a.m. cortisol (~g/dl) Range Mean (n) SO
9-25 14.4 (22) 4.8
12-42 27.5 (37) 7.7
25-130 49.1 (19) 24.8
13-34 22.2 (12) 5.7
