Vitamin D receptor gene polymorphism and bone mineral density in hypercalciuric calcium-stone-forming patients.
Reduced bone mineral density (BMD) and an increased risk of vertebral fracture have been reported in calcium-stone-forming (CSF) patients presenting with idiopathic hypercalciuria. We investigated the association between BsmI vitamin D receptor (VDR) polymorphism and BMD in 68 hypercalciuric CSF patients (35 males and 33 premenopausal females, mean age +/- SD = 39 +/- 10 years). BMD was measured at lumbar spine (L2-L4) and femur neck sites using dual energy X-ray absorptiometry. A 72-hour dietary record and a 24-hour urine sample were obtained from each patient to determine calcium intake and excretion. The allelic frequency found for the sample as a whole was 16% BB, 44% Bb and 40% bb. Mean BMD values did not significantly differ among BB, Bb and bb patients at L2-L4 (1.162 +/- 0.10, 1.133 +/- 0.11 and 1.194 +/- 0.19 g/cm2, mean +/- SD, respectively) or at neck sites (0.920 +/- 0.11, 0.931 +/- 0.15 and 0.982 +/- 0.15 g/cm2, respectively). Calcium intake and excretion were also not significantly different among the three genotypes. Patients were then divided into two groups, normal BMD, T-score > or =-1 (n = 34) and low BMD, T-score <-1 (n = 34), to further evaluate the allele influence on previous bone loss. Despite a trend for a higher mean BMD at spine or neck sites for patients with one or two b alleles when compared to BB patients, the difference did not reach statistical significance. The distribution of BB, Bb and bb genotypes in the low-bone-mass group (15, 47 and 38%, respectively) was similar to that in the normal-bone-mass group (18, 41 and 14%, respectively). These data suggest that BsmI VDR polymorphism does not play an important role in the bone loss seen in hypercalciuric CSF patients.
Heilberg
Ita Pfeferman
IP
Nephrology Division, Universidade Federal de São Paulo, Escola Paulista de Medicina, São Paulo, Brazil. ipheilberg@nefo.epm.br
Teixeira
Sergio Henrique
SH
Martini
Ligia Araujo
LA
Boim
Mirian Aparecia
MA
D000328:Adult; D015519:Bone Density; D002118:Calcium / Q000652:urine*; D004032:Diet; D005260:Female; D005272:Femur Neck / Q000378:metabolism; D005838:Genotype; D006801:Humans; D007669:Kidney Calculi / Q000737:chemistry*; D008159:Lumbar Vertebrae / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic; D017697:Premenopause; D018167:Receptors, Calcitriol / Q000235:genetics*
D018167:Receptors, Calcitriol; D002118:Calcium