Vitamin D Deficiency Does Not Impair Metabolic Improvements After Gastric Bypass

Background: Vitamin D deficiency is a long-known cause of calcium metabolism and bone disorders. More recently, it has also been identified as a potential risk factor for obesity and diabetes. Surgical alterations of the gastrointestinal tract associated with lipid malabsorption can conceivably contribute to vitamin D deficiency. Objective: To assess the prevalence of vitamin D deficiency and secondary hyperparathyroidism in patients with obesity before and after gastric bypass (RYGB) surgery and their impact in weight loss and glycemic profile. Setting: Public Hospital, University Methods: Patients (n=553) were subjected either to classic RYGB (n=415) or to long biliopancreatic limb metabolic RYGB (n=138). Anthropometric and biochemical parameters related to calcium and glucose metabolism were prospectively evaluated for up to 36 months after the procedure. Results: Both RYGB variants were effective in achieving sustained weight loss and long-term improvement in glycemic control. At 36 months, vitamin D deficiency and secondary hyperparathyroidism were present in 91.9% and 72.5% of patients, respectively, compared with 87.1% and 10.5% before surgery. 25-hydroxyvitamin D (25(OH)D) levels were negatively correlated with parathyroid hormone concentrations, but showed no significant correlations with excess weight loss, fasting glucose or HbA1c. Conclusion: Vitamin D deficiency and secondary hyperparathyroidism are highly prevalent before and after RYGB. However, these conditions do not appear to adversely affect postoperative weight loss or glycemic improvement.