Factors associated with secondary hyperparathyroidism in premenopausal women undergoing Roux-en-Y gastric bypass for the treatment of obesity.

Objective: To evaluate bone metabolism, bone density (BMD) and vertebral fractures in morbidly obese individuals.

Subjects And Methods: Case series of 29 premenopausal obese patients, 15 of whom had been submitted to bariatric surgery. Serum calcium, albumin, PTH and 25-hydroxy vitamin D (25OHD) were measured as well as bone densitometry of the lumbar spine and proximal femur, and lateral spine x-rays.

Results: High parathyroid hormone (PTH) levels were recorded in 46.6% of the surgical patients and in 21.4% of the non-surgical patients (p = 0.245); 26.7% of the former and 28.6% of the latter revealed levels 25OHD < 30 ng/mL (p = 1.000). Calcium intake was higher in the surgical group (p = 0.004) along with lower serum calcium concentrations (p = 0.019). There were no significant differences in bone mineral density (BMD) or in the prevalence of vertebral fractures between groups.

Conclusion: In premenopausal women undergoing Roux-en-Y gastric bypass there is important intestinal calcium mal absorption which seems to be the main factor causing secondary hyperparathyroidism.