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We would like to respond to the two letters 1,2 commenting on our
recent short report 3 on the subject of vitamin D levels in Asian
children. The diagnosis of rickets in a white infant associated with the
use of a potent sunscreen is interesting. The author quotes a study
linking the use of sunscreen with suppression of vitamin D 3 synthesis.
However, a more recent study found no association between sunscreen use
and Vitamin D metabolism4. In the current study no data was collected on
the use of sunscreen, although perhaps this should be considered for
future studies on Vitamin D.
For both the Asian and the NDNS 5 study serum 25-hydroxyvitamin D was
assayed with the INCSTAR kit which uses an equilibrium radio-immunoassay
procedure, although there were some minor methodological differences
between the two studies. In order to see whether these could in part
explain the difference in values seen in the two studies a number of
samples were analysed both in the Leicester laboratory, which analysed the
samples for this study, and the Dunn laboratory in Cambridge, which
analysed the national study. The two sets of values correlated very well
and whilst the values from the Cambridge laboratory were slightly higher
(mean difference +1.59nmol/l) the difference did not reach statistical
significance. The suggestion that the low concentrations found in the
Asian study may be a function of the analytical method therefore is not
substantiated.
Margaret Lawson, Senior Lecturer in Paediatric Nutrition
Childhood Nutrition Research Centre
Institute of Child Health, London WC1N 1EH
1 Zlotkin, S. Vitamin D concentrations in Asian children living in
England. BMJ 1999; 318, 1417.
2. Blumsohn, A. Concentrations found may be function of analytical
methodology used. BMJ 1999; 318, 1417.
3. Lawson, M.S., Thomas, M. Vitamin D concentrations in Asian
children
Aged 2 years living in England: population survey. BMJ 1999: 318, 28.
4. Farrerons et al.. Clinically prescribed sunscreen does not
decrease serum vitamin D concentration sufficiently either to induce
changes in parathyroid function or in metabolic markers Brit. J. Dermatol
1998; 139, 422.
5. Gregory et al. 1995. National Diet and Nutritional Survey:
Children
aged 1.5-4.5 years. London. HMSO.
Vitamin D levels and Asian Children
Vitamin D levels and Asian Children
We would like to respond to the two letters 1,2 commenting on our
recent short report 3 on the subject of vitamin D levels in Asian
children. The diagnosis of rickets in a white infant associated with the
use of a potent sunscreen is interesting. The author quotes a study
linking the use of sunscreen with suppression of vitamin D 3 synthesis.
However, a more recent study found no association between sunscreen use
and Vitamin D metabolism4. In the current study no data was collected on
the use of sunscreen, although perhaps this should be considered for
future studies on Vitamin D.
For both the Asian and the NDNS 5 study serum 25-hydroxyvitamin D was
assayed with the INCSTAR kit which uses an equilibrium radio-immunoassay
procedure, although there were some minor methodological differences
between the two studies. In order to see whether these could in part
explain the difference in values seen in the two studies a number of
samples were analysed both in the Leicester laboratory, which analysed the
samples for this study, and the Dunn laboratory in Cambridge, which
analysed the national study. The two sets of values correlated very well
and whilst the values from the Cambridge laboratory were slightly higher
(mean difference +1.59nmol/l) the difference did not reach statistical
significance. The suggestion that the low concentrations found in the
Asian study may be a function of the analytical method therefore is not
substantiated.
Margaret Lawson, Senior Lecturer in Paediatric Nutrition
Childhood Nutrition Research Centre
Institute of Child Health, London WC1N 1EH
1 Zlotkin, S. Vitamin D concentrations in Asian children living in
England. BMJ 1999; 318, 1417.
2. Blumsohn, A. Concentrations found may be function of analytical
methodology used. BMJ 1999; 318, 1417.
3. Lawson, M.S., Thomas, M. Vitamin D concentrations in Asian
children
Aged 2 years living in England: population survey. BMJ 1999: 318, 28.
4. Farrerons et al.. Clinically prescribed sunscreen does not
decrease serum vitamin D concentration sufficiently either to induce
changes in parathyroid function or in metabolic markers Brit. J. Dermatol
1998; 139, 422.
5. Gregory et al. 1995. National Diet and Nutritional Survey:
Children
aged 1.5-4.5 years. London. HMSO.
Competing interests: No competing interests