Clinical Endocrinology (1977) 7 , Suppl., 239s-3-44s.
l a - H Y D R O X Y V I T A M I N D3 I N T H E T R E A T M E N T O F NUTRITIONAL A N D METABOLIC RICKETS A N D OSTEOMALACIA J.M. G E R T N E R , D.B. BRENTON A N D R.H.T. EDWARDS Department of Human Metabolism University CoNege Hospital Medical School, London, U.K.
S UM M A R Y
Five patients with nutritional osteomalacia or rickets and six children with rickets unresponsive to physiological doses of vitamin D were treated with 1a-hydroxyvitamin D, (la-OHD,). Patients with nutritional osteornalacia responded to l-)pg/day of la-OHD3. The most striking findings were rises in plasma calcium and, in one case, a decrease in faecal calcium. In some cases there was a rise in plasma phosphorus, alkaline phosphatase remained unchanged. There was radiological healing. In three patients with cystinosis and one with hypophosphatsemia and Banter’s syndrome 2 p g of la-OHD3 produced healing of rickets. Plasma phosphate rose on treatment, possibly by a suppression of parathyroid activity. The response t o such low doses of la-OHD3 suggests impaired la-hydroxylation of 25-hydroxyvitamin D in these patients. A patient with intestinal malabsorption was resistant to high doses of la-OHD3 by mouth but responded t o parenteral administration. A boy with osteopetrosis and the biochemical changes of rickets was resistant t o large doses of la-OHD3 presumably because o f failure of osseous response. la-hydroxyvitamin D3 (la-OHD3) is an analogue of the active metabolite of vitamin D, 1,25-dihydroxyvitamin D3 (1 25{0H)zD3). la-OHD3 appears to be converted rapidly in vivo to 1,25-(OH)2D3 and finds its main clinical application in states where natural 1 ,25{0H)2 D3 production is impaired. We have been interested in the use of 1 ,25{0H)2D3 in rare metabolic bone diseases in which the existence of any form of disturbance of C-1 hydroxylation of 25hydroxyvitamin D3 (25-OHD3) is a matter of conjecture. Thus we have used la-OHD3, not only as a therapeutic agent but also as a tool t o gain more information on the biochemical disturbances involved in the disorders examined. Because of the rarity of these disorders controlled studies and the examination of large groups of affected patients were not undertaken. In order t o establish the physiological requirements of la-OHD3 in humans without metabolic bone disease, we treated five patients with nutritional vitamin deficiency. Correspondence: Dr J . M . Gertner, Department of Pediatrics, Yale University School of Medicine, 3 3 Ceder Street. New Haven, Connecticut 06510, U.S.A.
239s
J. iC.1. Gertner, D. B. Brenton and R. H. T. Edwards
240s
PATIENTS A N D METHODS Table 1 gives clinical and biochemical details of the patients with nutritional vitamin D deficiency at the time treatment with la-OHD3 was started. Table 2 gives sirmlar information for the patients with rickets resistant to physiological doses of vitamin D. Standard laboratory techniques were used to measure calcium, phosphorus, and alkaline phosphatase. PTH was measured by the method of Berson & Yalow (1 963) and 25-OHD3 by a modification of the method of Haddad & Chyu (1 971). Table 1. Clinical and biochemical details of patients presenting with nutritional vitamin D deficiency Patient
Sex
Age
Diagnosis
Previous Vit. D (treatment)
Calcium (mg/dl)
Phos. (mg/dl)
Plasma Alk. P. (KAU)
254HD, (ngiml)
1 8 months earlier NO NO NO NO
8.5
2.3
16
3
9 .O 6.7 8.7 7.9
1.9 4 .O 2.0 2.9
21 36 13 54
4 2
(years)
K.D.
64
F
A
E.H.
61 15 21 20
F
A. G A
E.A. P.G. J.P.
M' F F
A
A
A , nutritional vitamin D deficiency:
3
G,previous gastrectomy.
Table 2. Clinical and biochemical details of patients presenting with rickets resistant to physiological doses of vitamin D
Patient
S.B. S.C.
S.R. J.C.
R.K. P.W.
Age (yeus)
8.3 5.3 3.9 6.5 0.5 7.3
Sex Diagnosis
M
B
LM IvI
B B C D
M F M
E
Previous Vit. D treatment
Calcium Phos. (mg/dl) (mg/dl)
D, 0.9mg/day D, 0.5mglday D, 1 .O mg/day D, 0.05mg/day D, I.Omg/day (PO)
D,
9.6 9.2 9.1 8.9 4.7 1.6
2.8 2.6 0.9 0.6 5.6 2.5
Plasma 25-OHD, Serum Alk. P (ng/ml) PTH (KAU) (ng/ml) 15 19 14 42 129 68
204 59 228 42 2 10
925 1470 1200 650 3400
B, nephropathic cystinosis; C, hypophosphataemia and Bartter's syndrome; D, malabsorption - cause unknown; E, osteopetrosis.
RESULTS The response to la-OHD3 given orally dissolved in propylene glycol to the five patients with nutritional vitamin D deficiency are shown in Fig. 1. In all cases there was improvement on bone pain and rnyopathy and healing of radiological rickets. EA took his medication irregularly. He became hypocalcaemic while off medication but his plasma calcium rose within 4 days when he returned to his treatment regimen. PG presented with severe osteomalacia and was started on la-OHD3 while on full metabolic balance. Fig. 2 shows the rapid increase in calcium absorption during the study period on a dose of 1 pg a day of la-OHD3. There was virtually no change in plasma biochemistry during this period.
I a-OHD3 in treatment o f rickets and osteomalacia
I
I
I
2
4
6
I
I
I
8
10
12
241s
I
1
14
16PG
50
20 loo
Time (weeks)
Fig. 1. Nutritional rickets and osteornalacia: biochemical response to lol-OHD,.
e-
2o out A 25
PG 0
/@-.\,,e-e
t
L LLLLLLU I I I I I l l I l I I I I I I I I I I I I I I I I I 9 I I 13 I5 17 19 21 2 3 2 5 2 7 2 9 I 3 5 7 9 / I
b 2 6 6 55
April 1976
May1976
Fig. 2 . Nutritional osteornalacia: metabolic balance on 1 ug/day of lol-OHD,
242s
J . M, Gertner. D. B. Brenton and R. H. T. Edwards
Of the children with rickets resistant to physiological doses of vitamin D, four had hypophosphataemic states, the fifth had intestinal malabsorption, while the sixth had biochemical changes resembling those of rickets while on treatment for osteopetrosis. Fig. 3 indicates the response obtained when three children with nephropathic cystinosis (SR, SC and SB) and one with hypophosphataemic rickets and Bartter's syndrome (JC) were treated with la-OHD3. There was rise in plasma phosphate in all cases. In all these patients there was complete healing of epiphyseal rickets on la-OHD3 although SR showed increased femoral bowing during the treatment period. None of the patients developed serious hypercalcaemia on treatment and there was no evidence of a harmful effect on glomerular renal function. In the patient with coincident hypophosphataemic rickets and Bartter's syndrome, Ia-OHD3 therapy had no effect on the hypokalaemic alkalosis.
(weeks)
Time
(months)
Fig. 3 . Biochemical response to la-OHD, in four patients with renal tubular rickets.
A 4-month-old baby who presented with hypocalcaemic convulsions associated with rickets and malabsorption failed initially to respond to 1Opg laQHD3 given orally but a change to 2 p g daily intramuscularly produced a rapid resolution of symptoms. PW was a 5-year-old boy with osteopetrosis treated with a low calcium regimen as described by Dent & Smellie (1965). This regimen lead to hypocalcaemia and he has a low plasma phosphate and elevated alkaline phosphatase. There was no response to la-OHD3 even in doses of 10 &day.
I a-OHD,in treatment o f rickets and osteomalacia
‘43s
DISCUSSION la-OHD, was used t o treat patients with nutritional rickets and osteomalacia because of its rapid action and the ease with which its effect can be reversed. Bone lesions were healed in all cases and there was biochemical response t o 2 ~ g l d a yin all cases receiving this dose. The effect appears to start after 7-10 days of treatment. Plasma phosphate rose in some cases but there was no rise in alkaline phosphatase. This contrasts with the ‘flare’ often seen when vitamin D is used. Current theory holds that hypophosphataemic patients with adequate vitamin D stores should be synthesizing large quantities o f I ,95-(OH)2 D3 stimulated by their presumed low intracellular phosphate concentration (Tanaka & DeLuca, 1973). The response to small doses of la-OHD, shown by our hypophosphataemic patients carries the implication that there exists at least a relative impairment of la-hydroxylation of 25-OHD3 in these cases. A similar observation has been made by Rasmussen er al. (1976) in the case of sex-linked hypophosphataemic rickets. In all the cystinotic patients, plasma phosphate rose on treatment. There was a transient rise in plasma phosphate in patients with Batter’s syndrome. It follows that these patients’ tubular phosphate reabsorption mechanism, though abnormal, was capable of being modulated by the admistration of la-OHD3. We consider it more likely that this effect is mediated through a fall in circulating PTH levels rather than through a direct antiphosphaturic effect of la-OHD3 or 1,2S-(OH)2 D3. The case of RK represents a form of ’resistant’ rickets in which resistance to vitamin D and its metabolites is due to steatorrhoea. As la-OHD, has to be absorbed and converted to 1,2S-(0H),D3 before it can act, malabsorption may impair its effects. It is not known whether 1,25jOH’), D3 by acting drectly on intestinal mucosa, might be more effective in this situation. The boy with osteopetrosis showed extreme resistance to 1 a-OHD, . Most patients with this disease pass through a phase in w h c h the radiological appearances suggest rickets (Graham et al., 1974). In our patient treated with a low calcium diet, abnormal epiphyseal appearances persisted and the patient’s plasma and urinary biochemistry began t o resemble that seen in rickets. The resistance to la-OHD, cannot be attributed solely to the patient’s low calcium diet as vitamin D induced hypercalcaemia can occur even when no calcium is being taken orally (Counts et al., 1975). It seems more reasonable t o regard the whole biochemical picture as a consequence of the inability of osteocytes and osteoclasts to resorb bone. Thus the low calcium diet would cause a fall in plasma calcium and secondary hyperparathyroidism. The patient demonstrated renal sensitivity but osseous resistance to F’TH (Parfitt, 1976). The lack of response to high doses of la-OHD, would then be due to a parallel failure of osseous response t o the bone resorbing active metabolite of vitamin D. REFERENCES BERSON, S.A., YALOW, R.S.. AURBACH, C.D. & POTTS, J.T. (1963) Immunoassay of bovine and human parathyroid hormone. Proceedings o f the National Academy of Sciences of the United States ofAmerica. 4 9 , 6 1 3 4 1 7 . COUNTS, S.J., BAYLINK, D.J., SHEN, F.H.. S H E R R A R D , D.J. & HICKMAN, R.O. (1975) Vitamin D intoxication in an anephric child. Annals of Internal Medicine. 82, 196-200. DENT, C.E., SMELLIE. J . M . & WATSON, L. (1965) Studies in osteopetrosis. Archives of Disease o f Childhood, 40,7-15.
244s
f.M . Gertner, D. B . Brenton and R. H. T. Edwards
GRAHAM, C.B., RUDKE, U. & EKLOF, 0.(1974) Osteopetrosis. Progress i n Pediatric Radiology, 4, 37.5402. HADDAD, J.G. & CHYU, K.J. (1971) Competitive protein-binding assay for 25hydroxycholecalciferol. Journal of Clinical Endocrinology and Metabolism. 33,992-99.5. PARFITT, A.M. (1976) The action of parathyroid hormone on bone (Part IV). Metabolism. 25, 1157-1188. RASMUSSEN, H., ANAST, C., PARK, I., HAUSSLER, M., LANE, J. & PECHET, M. (1976) l&tiD, in the treatment of hypophosphataemic rickets. Clinical Research, 2 4 , 4 8 6 A . TANAKA, Y . & DELUCA, H.E. (1973) The control of 2541ydroxyvitamin D metabolism by inorganic phosphorus. Archives ofBiochem'stry and Biophysics, 154,566-574.
l a - H Y D R O X Y V I T A M I N D3 I N T H E T R E A T M E N T O F NUTRITIONAL A N D METABOLIC RICKETS A N D OSTEOMALACIA J.M. G E R T N E R , D.B. BRENTON A N D R.H.T. EDWARDS Department of Human Metabolism University CoNege Hospital Medical School, London, U.K.
S UM M A R Y
Five patients with nutritional osteomalacia or rickets and six children with rickets unresponsive to physiological doses of vitamin D were treated with 1a-hydroxyvitamin D, (la-OHD,). Patients with nutritional osteornalacia responded to l-)pg/day of la-OHD3. The most striking findings were rises in plasma calcium and, in one case, a decrease in faecal calcium. In some cases there was a rise in plasma phosphorus, alkaline phosphatase remained unchanged. There was radiological healing. In three patients with cystinosis and one with hypophosphatsemia and Banter’s syndrome 2 p g of la-OHD3 produced healing of rickets. Plasma phosphate rose on treatment, possibly by a suppression of parathyroid activity. The response t o such low doses of la-OHD3 suggests impaired la-hydroxylation of 25-hydroxyvitamin D in these patients. A patient with intestinal malabsorption was resistant to high doses of la-OHD3 by mouth but responded t o parenteral administration. A boy with osteopetrosis and the biochemical changes of rickets was resistant t o large doses of la-OHD3 presumably because o f failure of osseous response. la-hydroxyvitamin D3 (la-OHD3) is an analogue of the active metabolite of vitamin D, 1,25-dihydroxyvitamin D3 (1 25{0H)zD3). la-OHD3 appears to be converted rapidly in vivo to 1,25-(OH)2D3 and finds its main clinical application in states where natural 1 ,25{0H)2 D3 production is impaired. We have been interested in the use of 1 ,25{0H)2D3 in rare metabolic bone diseases in which the existence of any form of disturbance of C-1 hydroxylation of 25hydroxyvitamin D3 (25-OHD3) is a matter of conjecture. Thus we have used la-OHD3, not only as a therapeutic agent but also as a tool t o gain more information on the biochemical disturbances involved in the disorders examined. Because of the rarity of these disorders controlled studies and the examination of large groups of affected patients were not undertaken. In order t o establish the physiological requirements of la-OHD3 in humans without metabolic bone disease, we treated five patients with nutritional vitamin deficiency. Correspondence: Dr J . M . Gertner, Department of Pediatrics, Yale University School of Medicine, 3 3 Ceder Street. New Haven, Connecticut 06510, U.S.A.
239s
J. iC.1. Gertner, D. B. Brenton and R. H. T. Edwards
240s
PATIENTS A N D METHODS Table 1 gives clinical and biochemical details of the patients with nutritional vitamin D deficiency at the time treatment with la-OHD3 was started. Table 2 gives sirmlar information for the patients with rickets resistant to physiological doses of vitamin D. Standard laboratory techniques were used to measure calcium, phosphorus, and alkaline phosphatase. PTH was measured by the method of Berson & Yalow (1 963) and 25-OHD3 by a modification of the method of Haddad & Chyu (1 971). Table 1. Clinical and biochemical details of patients presenting with nutritional vitamin D deficiency Patient
Sex
Age
Diagnosis
Previous Vit. D (treatment)
Calcium (mg/dl)
Phos. (mg/dl)
Plasma Alk. P. (KAU)
254HD, (ngiml)
1 8 months earlier NO NO NO NO
8.5
2.3
16
3
9 .O 6.7 8.7 7.9
1.9 4 .O 2.0 2.9
21 36 13 54
4 2
(years)
K.D.
64
F
A
E.H.
61 15 21 20
F
A. G A
E.A. P.G. J.P.
M' F F
A
A
A , nutritional vitamin D deficiency:
3
G,previous gastrectomy.
Table 2. Clinical and biochemical details of patients presenting with rickets resistant to physiological doses of vitamin D
Patient
S.B. S.C.
S.R. J.C.
R.K. P.W.
Age (yeus)
8.3 5.3 3.9 6.5 0.5 7.3
Sex Diagnosis
M
B
LM IvI
B B C D
M F M
E
Previous Vit. D treatment
Calcium Phos. (mg/dl) (mg/dl)
D, 0.9mg/day D, 0.5mglday D, 1 .O mg/day D, 0.05mg/day D, I.Omg/day (PO)
D,
9.6 9.2 9.1 8.9 4.7 1.6
2.8 2.6 0.9 0.6 5.6 2.5
Plasma 25-OHD, Serum Alk. P (ng/ml) PTH (KAU) (ng/ml) 15 19 14 42 129 68
204 59 228 42 2 10
925 1470 1200 650 3400
B, nephropathic cystinosis; C, hypophosphataemia and Bartter's syndrome; D, malabsorption - cause unknown; E, osteopetrosis.
RESULTS The response to la-OHD3 given orally dissolved in propylene glycol to the five patients with nutritional vitamin D deficiency are shown in Fig. 1. In all cases there was improvement on bone pain and rnyopathy and healing of radiological rickets. EA took his medication irregularly. He became hypocalcaemic while off medication but his plasma calcium rose within 4 days when he returned to his treatment regimen. PG presented with severe osteomalacia and was started on la-OHD3 while on full metabolic balance. Fig. 2 shows the rapid increase in calcium absorption during the study period on a dose of 1 pg a day of la-OHD3. There was virtually no change in plasma biochemistry during this period.
I a-OHD3 in treatment o f rickets and osteomalacia
I
I
I
2
4
6
I
I
I
8
10
12
241s
I
1
14
16PG
50
20 loo
Time (weeks)
Fig. 1. Nutritional rickets and osteornalacia: biochemical response to lol-OHD,.
e-
2o out A 25
PG 0
/@-.\,,e-e
t
L LLLLLLU I I I I I l l I l I I I I I I I I I I I I I I I I I 9 I I 13 I5 17 19 21 2 3 2 5 2 7 2 9 I 3 5 7 9 / I
b 2 6 6 55
April 1976
May1976
Fig. 2 . Nutritional osteornalacia: metabolic balance on 1 ug/day of lol-OHD,
242s
J . M, Gertner. D. B. Brenton and R. H. T. Edwards
Of the children with rickets resistant to physiological doses of vitamin D, four had hypophosphataemic states, the fifth had intestinal malabsorption, while the sixth had biochemical changes resembling those of rickets while on treatment for osteopetrosis. Fig. 3 indicates the response obtained when three children with nephropathic cystinosis (SR, SC and SB) and one with hypophosphataemic rickets and Bartter's syndrome (JC) were treated with la-OHD3. There was rise in plasma phosphate in all cases. In all these patients there was complete healing of epiphyseal rickets on la-OHD3 although SR showed increased femoral bowing during the treatment period. None of the patients developed serious hypercalcaemia on treatment and there was no evidence of a harmful effect on glomerular renal function. In the patient with coincident hypophosphataemic rickets and Bartter's syndrome, Ia-OHD3 therapy had no effect on the hypokalaemic alkalosis.
(weeks)
Time
(months)
Fig. 3 . Biochemical response to la-OHD, in four patients with renal tubular rickets.
A 4-month-old baby who presented with hypocalcaemic convulsions associated with rickets and malabsorption failed initially to respond to 1Opg laQHD3 given orally but a change to 2 p g daily intramuscularly produced a rapid resolution of symptoms. PW was a 5-year-old boy with osteopetrosis treated with a low calcium regimen as described by Dent & Smellie (1965). This regimen lead to hypocalcaemia and he has a low plasma phosphate and elevated alkaline phosphatase. There was no response to la-OHD3 even in doses of 10 &day.
I a-OHD,in treatment o f rickets and osteomalacia
‘43s
DISCUSSION la-OHD, was used t o treat patients with nutritional rickets and osteomalacia because of its rapid action and the ease with which its effect can be reversed. Bone lesions were healed in all cases and there was biochemical response t o 2 ~ g l d a yin all cases receiving this dose. The effect appears to start after 7-10 days of treatment. Plasma phosphate rose in some cases but there was no rise in alkaline phosphatase. This contrasts with the ‘flare’ often seen when vitamin D is used. Current theory holds that hypophosphataemic patients with adequate vitamin D stores should be synthesizing large quantities o f I ,95-(OH)2 D3 stimulated by their presumed low intracellular phosphate concentration (Tanaka & DeLuca, 1973). The response to small doses of la-OHD, shown by our hypophosphataemic patients carries the implication that there exists at least a relative impairment of la-hydroxylation of 25-OHD3 in these cases. A similar observation has been made by Rasmussen er al. (1976) in the case of sex-linked hypophosphataemic rickets. In all the cystinotic patients, plasma phosphate rose on treatment. There was a transient rise in plasma phosphate in patients with Batter’s syndrome. It follows that these patients’ tubular phosphate reabsorption mechanism, though abnormal, was capable of being modulated by the admistration of la-OHD3. We consider it more likely that this effect is mediated through a fall in circulating PTH levels rather than through a direct antiphosphaturic effect of la-OHD3 or 1,2S-(OH)2 D3. The case of RK represents a form of ’resistant’ rickets in which resistance to vitamin D and its metabolites is due to steatorrhoea. As la-OHD, has to be absorbed and converted to 1,2S-(0H),D3 before it can act, malabsorption may impair its effects. It is not known whether 1,25jOH’), D3 by acting drectly on intestinal mucosa, might be more effective in this situation. The boy with osteopetrosis showed extreme resistance to 1 a-OHD, . Most patients with this disease pass through a phase in w h c h the radiological appearances suggest rickets (Graham et al., 1974). In our patient treated with a low calcium diet, abnormal epiphyseal appearances persisted and the patient’s plasma and urinary biochemistry began t o resemble that seen in rickets. The resistance to la-OHD, cannot be attributed solely to the patient’s low calcium diet as vitamin D induced hypercalcaemia can occur even when no calcium is being taken orally (Counts et al., 1975). It seems more reasonable t o regard the whole biochemical picture as a consequence of the inability of osteocytes and osteoclasts to resorb bone. Thus the low calcium diet would cause a fall in plasma calcium and secondary hyperparathyroidism. The patient demonstrated renal sensitivity but osseous resistance to F’TH (Parfitt, 1976). The lack of response to high doses of la-OHD, would then be due to a parallel failure of osseous response t o the bone resorbing active metabolite of vitamin D. REFERENCES BERSON, S.A., YALOW, R.S.. AURBACH, C.D. & POTTS, J.T. (1963) Immunoassay of bovine and human parathyroid hormone. Proceedings o f the National Academy of Sciences of the United States ofAmerica. 4 9 , 6 1 3 4 1 7 . COUNTS, S.J., BAYLINK, D.J., SHEN, F.H.. S H E R R A R D , D.J. & HICKMAN, R.O. (1975) Vitamin D intoxication in an anephric child. Annals of Internal Medicine. 82, 196-200. DENT, C.E., SMELLIE. J . M . & WATSON, L. (1965) Studies in osteopetrosis. Archives of Disease o f Childhood, 40,7-15.
244s
f.M . Gertner, D. B . Brenton and R. H. T. Edwards
GRAHAM, C.B., RUDKE, U. & EKLOF, 0.(1974) Osteopetrosis. Progress i n Pediatric Radiology, 4, 37.5402. HADDAD, J.G. & CHYU, K.J. (1971) Competitive protein-binding assay for 25hydroxycholecalciferol. Journal of Clinical Endocrinology and Metabolism. 33,992-99.5. PARFITT, A.M. (1976) The action of parathyroid hormone on bone (Part IV). Metabolism. 25, 1157-1188. RASMUSSEN, H., ANAST, C., PARK, I., HAUSSLER, M., LANE, J. & PECHET, M. (1976) l&tiD, in the treatment of hypophosphataemic rickets. Clinical Research, 2 4 , 4 8 6 A . TANAKA, Y . & DELUCA, H.E. (1973) The control of 2541ydroxyvitamin D metabolism by inorganic phosphorus. Archives ofBiochem'stry and Biophysics, 154,566-574.
