Vitamin D status and parathyroid hormone in patients with severe obesity who undergo and not undergo gastric bypass.

To determine the status of 25(OH)D and parathyroid hormone (PTH) levels in patients with severe obesity who undergo and not undergo gastric bypass (GB); and analyzed their correlation with the degree of obesity and fat mass. Cross-sectional study in 34 patients, analyzed in two groups: a) patients who not undergo GB and b) patients who did undergo GB. Height, weight, BMI, body composition, % excess weight loss (EWL) and % total weight loss (TWL) were determinate. 25(OH)D level was categorized according to the Endocrine Society criteria. Mean age was of 37.24 ± 5.83 vs 40.82 ± 9.03 years (P = 0.021) and BMI of 44.92 ± 8.63 vs 31.28 ± 5.60 kg/m2 (P = 0.001) in patients who did not undergo GB and underwent GB respectively. Patients who underwent GB showed decreased levels of 25(OH)D: 14.04 ± 10.42 ng/mL vs patients without surgery 31.95 ± 31.00 ng/mL (P < 0.001). Vitamin D deficiency was identified in 70% patients having GB vs 59% patients without surgery (P < 0.05). Of all patients with GB, 35% were diagnosed with hyperparathyroidism vs 29% of those without GB (P = 0.492). Serum 25(OH)D concentrations were disclosed a significant inverse relationship with the % TWL after surgery, but not with weight, BMI and fat mass. Vitamin D deficiency is prevalent in patients with severe obesity and patients who did undergo GB. The major determinant of low levels of 25(OH)D was % TWL after surgery. Hyperparathyroidism did not indicate vitamin D deficiency. [ABSTRACT FROM AUTHOR]