Sir,

I read with interest the article “Study of 25 OH calcium and phosphorus in normal subjects and patients with renal calculi, from Dr. Jaffer Naqvi’s unit (JPMA 1988,37:198-199).
1:25 Dihydroxy vitamin D 3 is the form of Vit D 3 that accelerates calcium absorption. The published study measures 25 hydroxy P 3 (a precursor of 1:25 D I hydroxy D 3) which is present in chronic uremics but is so ineffective in absorbing calcium that the patients develop renal osteodystrophy and secondary hyper parathyroi­dism.
Whilst the authors deserve to be commended for this article, a study of 1:25 dthydroxy Vit D 3 will be more valuable. As disorders of vitamin metabolism are rare, a sample population of 100 patients may be more appro­priate.
Department of Surgery (Urology), Faculty of Health Sciences, The Aga Khan University, Kaxacli.

Jamsheer Talati