Age and Ageing (1978) 7, 91
VITAMIN D HYDROXYLATION IN YOUTH AND OLD AGE CLAIRE RUSHTON
Medical Student, University of Southampton
Summary
INTRODUCTION
Osteomalacia is common in the elderly (Anderson et al. 1966, Chalmers et al. 1967). This is reflected in the low levels of 25-hydroxy-vitamin D (25OHD) often found in old people from geriatric units (Corless et al. 1975). Likely causes include dietary deficiency and reduced sunlight exposure (MacLennan et al. 1972, Hodkinson et al, 1973). Since 25OHD is the liver metabolite of vitamin D, low levels might also be expected in liver disease and this has proved to be the case (Wagonfeld et al. 1976). Ageing is associated with reduced liver function (Hyams 1973) so that a reduced 25-hydroxylation of vitamin D might be yet another explanation for old people having low 25OHD concentrations. This paper describes an attempt to investigate the hypothesis. Methods The subjects in the study were 10 patients in a geriatric assessment unit; 9 healthy young adults; and 7 healthy elderly subjects living at home. Their age ranges were 62-92, 21-27 and 69-87 years respectively. None had abnormal serum calcium, phosphate, alkaline phosphatase, bilirubin, albumin, SGOT or LDH levels. Heparinized blood samples were collected initially and at 1, 3, 7, 8 and 10 days. Immediately after the first blood collection, subjects were given 50 000 i.u. of ergocalciferol by subcutaneous injection. 25-Hydroxy-vitamin D levels were measured on samples using a method described by Belsey and his colleagues (19746). To minimize interassay errors, the six samples from each individual were assayed as one batch. RESULTS
The responses of plasma 25-hydroxy-vitamin D levels to the vitamin D injection in elderly in-patients, healthy young adults and healthy elderly people are shown in Figs. 1, 2 and 3, respectively. Statistical analysis In distinguishing the response to treatment from the original level of metabolite, the initial measurement was subtracted from each successive one. All data were tested
Downloaded from http://ageing.oxfordjournals.org/ at University of Nebraska-Lincoln Libraries on June 9, 2016
The effects of the subcutaneous injections of 50 000 i.u. of vitamin D on 25-hydroxy-vitamin D levels were measured in young controls, old people living at home, and in elderly in-patients. Responses were substantially reduced in both groups of old people, particularly in those living at home. This phenomenon may be due to the effects of ageing or disease on 25-hydroxylase activity.
92
Claire Rushton
10 Time in Day* —
Fig. 1. Response to vitamin D in elderly hospital patients.
1 2 3 4 5 6 7 6 9 1 0
Time kiDay*-~
Fig. 2. Response to vitamin D in healthy young people.
Downloaded from http://ageing.oxfordjournals.org/ at University of Nebraska-Lincoln Libraries on June 9, 2016
0 1 2 3 4 5 6 7 8 9
Vitamin D Hydroxylation in Youth and Old Age
93
Fig. 3. Response to vitamin D in healthy old people.
for equivariance, normality and independence, the three assumptions of the 'Anovar* procedure being used. The data then have an expectation of zero under the null hypothesis of no response to supplements. A two-factor classification with interactions produced the following results: Interaction—not significant at any level (F test) Factor I (day)—not significant at any level (F test) Factor II (group)—significant at 5% level (F test) Factor II {Group) Analysis Absolute responses: Group A—elderly in-patients 0.05 > P > 0.02 Group B—healthy young adults P< 0.001 Group C—healthy elderly subjects N.S. Comparison of significance levels: Student's t test Group B:A 0.1 > P > 0.05 Group B:C 0.02 >P> 0.01 Group C:A N.S.
Scheffitest Group B:A N.S. Group B:C 0.05 >P> 0.02 Group A:C N.S.
The contrast B - \ (A + C) was tested by Scheffe's method and found to be significant at the 5% level. This confirmed that young healthy adults responded better than both elderly groups and that the contrast between healthy old subjects and healthy young subjects was particularly prominent.
Downloaded from http://ageing.oxfordjournals.org/ at University of Nebraska-Lincoln Libraries on June 9, 2016
7 8 9 10 Tlm» In Days —.
94
Claire Rushton DISCUSSION
ACKNOWLEDGEMENTS
I would like to thank Professor M. R. P. Hall, Dr W. J. MacLennan and Mrs Judith Hamilton for their help and advice in conducting this study, Dr A. Forcado for his assistance during the early days of the study and Dr R. Dickson for his advice concerning the healthy elderly subjects. I am also grateful to Dr J. Wright for his statistical analysis. REFERENCES
I., CAMPBELL, A. E. R., DUNN, A. & RUNCIMAN, J. B. M. (1966) Osteomalacia in elderly women. Scott. Med. J. 11, 429.
ANDERSON,
BELSEY, R. E., CLARK, M. B., BERNAT, M., GLOWACKI, J., HOLICK, M. F., DE LUCA, H. F. & POTTS, J. T. (1974a). Physiological significance of plasma transport of vitamin D and its
metabolites. Am. J. Med. 57, 50. R. E., DE LUCA, H. F. & POTTS, J. T. (19746) A rapid assay for 25-hydroxy-vitamin D without preparative chromatography. J. Clin. Endocr. Metab. 38, 1046. CASTLEDEN, C. M., KAYE, C. M. & PARSONS, R. L. (1975) The effects of age on plasma levels of propranolol and practolol in man. Br.J. Clin. Pharm. 2, 303. CHALMERS, J., CONACHER, W. D. H., GARDNER, D. L. & SCOTT, P. J. (1967) Osteomalacia: a common disease in elderly women. J. Bone. Jt. Surg. 49B, 403. CORLESS, D., BOUCHER, B. J., BEER, M., GUPTA, S. B. & COHEN, R. D. (1975) Vitamin D status in long-stay geriatric patients. Lancet i, 1404. BELSEY,
Downloaded from http://ageing.oxfordjournals.org/ at University of Nebraska-Lincoln Libraries on June 9, 2016
The subcutaneous injection 50 000 i.u. of vitamin D produced higher levels of 25hydroxy-vitamin D in young adults than in either gToup of elderly subjects. It would also appear that the difference between the young adults and hospital patients was less striking than that between the former and healthy old people. This analysis might be misleading, however, since the difference resulted from a larger negative response in one healthy elderly subject. Old people might have responded poorly to vitamin D because the vitamin did not reach the liver. Vitamin D is transported bound to a plasma protein which moves with albumin in starch gel electrophoresis (Peterson 1976, Belsey et al. 1974a). Many plasma proteins do decline in disease and old age, but a very striking reduction would be required before this had more than a marginal effect on plasma vitamin D levels. The poor response might also have been due to the fact that most of the elderly subjects were on drug therapy. Both phenobarbitone and phenytoin induce the conversion of 25-hydroxy-vitamin D to inactive metabolites (Hahn et al. 1972). None of the subjects was on these drugs but it is possible that other drugs such as tranquillizers or antidiabetic agents might have a similar, as yet unrecognized, effect. The numbers of subjects studied were too small to justify an analysis of the effects of drug treatment. The most probable explanation for the phenomenon is that ageing and disease are responsible for a decline in 25-hydroxylation. Ageing has an important effect upon the metabolism of a variety of drugs of which a good example is that of propranolol (Castleden et al. 1975). 25-Hydroxy-vitamin D may be affected in a similar way. Work at present being conducted on 25-hydroxylase activity in young, middle-aged and old rats should confirm or refute this hypothesis (J. C. Hamilton & W. J. MacLennan, personal communication, 1977).
Vitamin D Hydroxylation in Youth and Old Age
95
J. J., BIRGE, S. J. & AVIOLI, L. W. (1972) Phenobarbital induced alterations in vitamin D metabolism. J. Clin. Invest. 51, 714. HODKINSON, H. M., ROUND, P., STANTON, B. R. & MORGAN, C. (1973) Sunlight, vitamin D and osteomalacia in the elderly. Lancet i, 910. HYAMS, D. E. (1973) Textbook of Geriatric Medicine and Gerontology Ed. J. C. Brocklehurst, p. 364. Edinburgh: Churchill Livingstone. MACLENNAN, W. J., CAIRD, F. I. & MCLEOD, C. C. (1972) Diet and bone rarefaction in old age. Age & Ageing 1, 131. PETERSON, P. A. (1976) Isolation and partial characterisation of a human vitamin D binding plasma protein. Biochem. J. 135, 415. HAHN,
WAGONFELD, J. B., BOLT, M., BOYER, J. L., NEMCHAUSKY, B. A., HORST, J. V. & ROSSENBERG, I. H.
(1976) Comparison of vitamin D and 25-hydroxy-vitamin D in the therapy of primary biliary cirrhosis. Lancet it, 391. Downloaded from http://ageing.oxfordjournals.org/ at University of Nebraska-Lincoln Libraries on June 9, 2016
VITAMIN D HYDROXYLATION IN YOUTH AND OLD AGE CLAIRE RUSHTON
Medical Student, University of Southampton
Summary
INTRODUCTION
Osteomalacia is common in the elderly (Anderson et al. 1966, Chalmers et al. 1967). This is reflected in the low levels of 25-hydroxy-vitamin D (25OHD) often found in old people from geriatric units (Corless et al. 1975). Likely causes include dietary deficiency and reduced sunlight exposure (MacLennan et al. 1972, Hodkinson et al, 1973). Since 25OHD is the liver metabolite of vitamin D, low levels might also be expected in liver disease and this has proved to be the case (Wagonfeld et al. 1976). Ageing is associated with reduced liver function (Hyams 1973) so that a reduced 25-hydroxylation of vitamin D might be yet another explanation for old people having low 25OHD concentrations. This paper describes an attempt to investigate the hypothesis. Methods The subjects in the study were 10 patients in a geriatric assessment unit; 9 healthy young adults; and 7 healthy elderly subjects living at home. Their age ranges were 62-92, 21-27 and 69-87 years respectively. None had abnormal serum calcium, phosphate, alkaline phosphatase, bilirubin, albumin, SGOT or LDH levels. Heparinized blood samples were collected initially and at 1, 3, 7, 8 and 10 days. Immediately after the first blood collection, subjects were given 50 000 i.u. of ergocalciferol by subcutaneous injection. 25-Hydroxy-vitamin D levels were measured on samples using a method described by Belsey and his colleagues (19746). To minimize interassay errors, the six samples from each individual were assayed as one batch. RESULTS
The responses of plasma 25-hydroxy-vitamin D levels to the vitamin D injection in elderly in-patients, healthy young adults and healthy elderly people are shown in Figs. 1, 2 and 3, respectively. Statistical analysis In distinguishing the response to treatment from the original level of metabolite, the initial measurement was subtracted from each successive one. All data were tested
Downloaded from http://ageing.oxfordjournals.org/ at University of Nebraska-Lincoln Libraries on June 9, 2016
The effects of the subcutaneous injections of 50 000 i.u. of vitamin D on 25-hydroxy-vitamin D levels were measured in young controls, old people living at home, and in elderly in-patients. Responses were substantially reduced in both groups of old people, particularly in those living at home. This phenomenon may be due to the effects of ageing or disease on 25-hydroxylase activity.
92
Claire Rushton
10 Time in Day* —
Fig. 1. Response to vitamin D in elderly hospital patients.
1 2 3 4 5 6 7 6 9 1 0
Time kiDay*-~
Fig. 2. Response to vitamin D in healthy young people.
Downloaded from http://ageing.oxfordjournals.org/ at University of Nebraska-Lincoln Libraries on June 9, 2016
0 1 2 3 4 5 6 7 8 9
Vitamin D Hydroxylation in Youth and Old Age
93
Fig. 3. Response to vitamin D in healthy old people.
for equivariance, normality and independence, the three assumptions of the 'Anovar* procedure being used. The data then have an expectation of zero under the null hypothesis of no response to supplements. A two-factor classification with interactions produced the following results: Interaction—not significant at any level (F test) Factor I (day)—not significant at any level (F test) Factor II (group)—significant at 5% level (F test) Factor II {Group) Analysis Absolute responses: Group A—elderly in-patients 0.05 > P > 0.02 Group B—healthy young adults P< 0.001 Group C—healthy elderly subjects N.S. Comparison of significance levels: Student's t test Group B:A 0.1 > P > 0.05 Group B:C 0.02 >P> 0.01 Group C:A N.S.
Scheffitest Group B:A N.S. Group B:C 0.05 >P> 0.02 Group A:C N.S.
The contrast B - \ (A + C) was tested by Scheffe's method and found to be significant at the 5% level. This confirmed that young healthy adults responded better than both elderly groups and that the contrast between healthy old subjects and healthy young subjects was particularly prominent.
Downloaded from http://ageing.oxfordjournals.org/ at University of Nebraska-Lincoln Libraries on June 9, 2016
7 8 9 10 Tlm» In Days —.
94
Claire Rushton DISCUSSION
ACKNOWLEDGEMENTS
I would like to thank Professor M. R. P. Hall, Dr W. J. MacLennan and Mrs Judith Hamilton for their help and advice in conducting this study, Dr A. Forcado for his assistance during the early days of the study and Dr R. Dickson for his advice concerning the healthy elderly subjects. I am also grateful to Dr J. Wright for his statistical analysis. REFERENCES
I., CAMPBELL, A. E. R., DUNN, A. & RUNCIMAN, J. B. M. (1966) Osteomalacia in elderly women. Scott. Med. J. 11, 429.
ANDERSON,
BELSEY, R. E., CLARK, M. B., BERNAT, M., GLOWACKI, J., HOLICK, M. F., DE LUCA, H. F. & POTTS, J. T. (1974a). Physiological significance of plasma transport of vitamin D and its
metabolites. Am. J. Med. 57, 50. R. E., DE LUCA, H. F. & POTTS, J. T. (19746) A rapid assay for 25-hydroxy-vitamin D without preparative chromatography. J. Clin. Endocr. Metab. 38, 1046. CASTLEDEN, C. M., KAYE, C. M. & PARSONS, R. L. (1975) The effects of age on plasma levels of propranolol and practolol in man. Br.J. Clin. Pharm. 2, 303. CHALMERS, J., CONACHER, W. D. H., GARDNER, D. L. & SCOTT, P. J. (1967) Osteomalacia: a common disease in elderly women. J. Bone. Jt. Surg. 49B, 403. CORLESS, D., BOUCHER, B. J., BEER, M., GUPTA, S. B. & COHEN, R. D. (1975) Vitamin D status in long-stay geriatric patients. Lancet i, 1404. BELSEY,
Downloaded from http://ageing.oxfordjournals.org/ at University of Nebraska-Lincoln Libraries on June 9, 2016
The subcutaneous injection 50 000 i.u. of vitamin D produced higher levels of 25hydroxy-vitamin D in young adults than in either gToup of elderly subjects. It would also appear that the difference between the young adults and hospital patients was less striking than that between the former and healthy old people. This analysis might be misleading, however, since the difference resulted from a larger negative response in one healthy elderly subject. Old people might have responded poorly to vitamin D because the vitamin did not reach the liver. Vitamin D is transported bound to a plasma protein which moves with albumin in starch gel electrophoresis (Peterson 1976, Belsey et al. 1974a). Many plasma proteins do decline in disease and old age, but a very striking reduction would be required before this had more than a marginal effect on plasma vitamin D levels. The poor response might also have been due to the fact that most of the elderly subjects were on drug therapy. Both phenobarbitone and phenytoin induce the conversion of 25-hydroxy-vitamin D to inactive metabolites (Hahn et al. 1972). None of the subjects was on these drugs but it is possible that other drugs such as tranquillizers or antidiabetic agents might have a similar, as yet unrecognized, effect. The numbers of subjects studied were too small to justify an analysis of the effects of drug treatment. The most probable explanation for the phenomenon is that ageing and disease are responsible for a decline in 25-hydroxylation. Ageing has an important effect upon the metabolism of a variety of drugs of which a good example is that of propranolol (Castleden et al. 1975). 25-Hydroxy-vitamin D may be affected in a similar way. Work at present being conducted on 25-hydroxylase activity in young, middle-aged and old rats should confirm or refute this hypothesis (J. C. Hamilton & W. J. MacLennan, personal communication, 1977).
Vitamin D Hydroxylation in Youth and Old Age
95
J. J., BIRGE, S. J. & AVIOLI, L. W. (1972) Phenobarbital induced alterations in vitamin D metabolism. J. Clin. Invest. 51, 714. HODKINSON, H. M., ROUND, P., STANTON, B. R. & MORGAN, C. (1973) Sunlight, vitamin D and osteomalacia in the elderly. Lancet i, 910. HYAMS, D. E. (1973) Textbook of Geriatric Medicine and Gerontology Ed. J. C. Brocklehurst, p. 364. Edinburgh: Churchill Livingstone. MACLENNAN, W. J., CAIRD, F. I. & MCLEOD, C. C. (1972) Diet and bone rarefaction in old age. Age & Ageing 1, 131. PETERSON, P. A. (1976) Isolation and partial characterisation of a human vitamin D binding plasma protein. Biochem. J. 135, 415. HAHN,
WAGONFELD, J. B., BOLT, M., BOYER, J. L., NEMCHAUSKY, B. A., HORST, J. V. & ROSSENBERG, I. H.
(1976) Comparison of vitamin D and 25-hydroxy-vitamin D in the therapy of primary biliary cirrhosis. Lancet it, 391. Downloaded from http://ageing.oxfordjournals.org/ at University of Nebraska-Lincoln Libraries on June 9, 2016
![Antipyrine induction and hepatic vitamin D hydroxylation in man [proceedings].](/assets/img/hold.png)
