Calcium metabolism in pre- and postmenopausal morbidly obese women at baseline and after laparoscopic Roux-en-Y gastric bypass

Background: The authors evaluated calcium metabolism in obese women, before and after menopause, at baseline and at 6 and 12 months after laparoscopic Roux-en-Y gastric bypass (LRYGBP). LRYGBP restricts food intake and produces physiological changes that may be similar to those after high Billroth II subtotal gastrectomy. Methods: Serum calcium (Ca), phosphate, bone-specific alkaline phosphatase (BSAP) and 25-hydroxyvitarnin D3 (25-OH D) were measured at baseline and 12 months after LRYGBP. Urinary N-telopeptide (u-NTX) was measured at baseline and serum C-telopeptide (s-CTX) at 6 and 12 months after LRYGBP. Parathormone (PTH) was measured at baseline an and 12 months after LRYGBP. Patients were divided into 2 groups: Group I (n=30) pre-menopausal women aged 18-42 y, and Group II (n=30) post-menopausal women aged 40-71 y. Patients with renal, hepatic, metabolic and bone disease, smoking women, as well as patients with u-NTX values at baseline >67 nMBCE/mMCr were excluded. Results: At baseline, PTH was elevated in 10% of patients in each group, correlated positively with BMI, and low serum calcium values were found in 30% of Group I and 16.7% of Group II. High values of serum C-telopetide were seen in Group I at 6 months after surgery and in Group II 12 months after LRYGBP. Group II showed a greater increase in BSAP at 12 months after LRYGBP. 25-OH D decreased in both groups, and a progressive increase in PTH was observed. Serum calcium did not change in both groups. Conclusion: Calcium metabolism is altered in pre- and post-menopausal women following LRYGBP. Calcium and vitamin D supplementation is strongly advised in all patients.