Vitamin D receptor polymorphisms in secondary hyperparathyroidism after Scopinaro's biliopancreatic diversion

Secondary hyperparathyroidism is a frequent metabolic complication of bariatric surgery. Individual differences in calcium absorption determine chronic secondary hyperparathyroidism after biliopancreatic diversion in half of the patients who have normal levels of 25-hydroxyvitamin D. We aimed to evaluate if certain vitamin D receptor polymorphisms may be responsible for the latter. Cases and controls study including 57 patients after biliopancreatic diversion with a mean serum 25-hydroxyvitamin D above 20 ng/mL, separated into those with secondary hyperparathyroidism (n = 26, cases) and those without it (n = 31, controls).

Genotyping for restriction-length-fragment polymorphisms of the vitamin D receptor gene was carried out for FOK1, BSM1, APA1, and TAQ1, and haplotype structure was also constructed.

There were no differences in the allelic or genotypes distribution of the four studied polymorphisms between patients and controls (P = 0.352 and P = 0.301 for FOK1, P = 0.733 and P = 0.924 for BSM1, P = 0.974 and P = 0.992 for APA1, and P = 0.995 and P = 0.928 for TAQ1, respectively). Haplotype analysis showed no differences between patients and controls (P = 0.495 for BAT, P = 1.000 for BAt, P = 0.508 for Bat and P = 0.924 for bAT haplotypes, respectively). Furthermore, haplotypes were not associated with serum PTH levels or with the ratio between serum PTH and 25-hydroxyvitamin D levels.

Chronic secondary hyperparathyroidism after biliopancreatic diversion in patients with normal levels of 25-hydroxyvitamin D is not dependent on vitamin D receptor gene polymorphisms.