Effect of Roux-en Y gastric bypass on bone metabolism in patients with morbid obesity: [Mansoura experiences]

ABSTRACT

Roux-en-Y gastric bypass [RYGBP] has been found to be the most efficient way to lose weight and maintain the weight loss in morbid obesity. However, with the formation of a new stomach and the modification of intestinal anatomy, there are significant changes on bone metabolism .The objectives of this study were to evaluate effects of weight loss on bone metabolism after Roux-en Y gastric bypass in patients with morbid obesity. Our study included 70 patients with morbid obesity, RYGBP was done for all patients. Daily postoperative oral supplementation with 1000 mg of calcium and 800 IU of vitamin D was done for each patient Body weight, BMJ, also Total body fat, Total lean tissue mass, Bone Mineral content [BMC], Bone Mineral density [BMD], Total bone area [TBA] [using DEXA], also, serum calcium, parathyroid hormone [PTH], 25-OH vitamin D, 24 hours urinary calcium and bone specific Alkaline phos-phatase [BSAP] were assessed preoperatively and one year after surgery. In our study females comprised 70% of cases. The mean age was 35 +/- 8.8 years. One year after RYGB Body weight [BW] decreased significantly from 132.8 +/- 26.5 to 90.3 +/- 17.3 kg [P=0.001]. Body Mass Index [BMI] decreased significantly from 48 +/- 7.3 to 32.6 +/- 4.1 kg/m2 [P= 0.001]. BMC decreased significantly from 2968.6 +/- 71.4 to 2700.8 +/- 45.4 gm [p = 0.001] BMD decreased significantly from 1.026 +/- 0.03 to 1.22 +/- 0.015 gm/cm[2] [P=0.001]. TBA decreased significantly from 2356.2 +/- 35.4 to 2216.3 +/- 43.5 cm2 [P=0.001]. Serum calcium, 24 hours urinary calcium and BSAP were non significantly decreased while 25 OH-vitamin D and PTH were non significantly increased after surgery. From this study, it is shown that Roux-en-Y gastric bypass operation gives very good results as regards reduction of body weight in morbidly obese patients. Postoperative supplementation with calcium and vitamin D partially correct osteoporosis. So, These patients need periodic follow up for Bone Mineral Density [BMD], PTH, calcium, serum vitamin D and markers of bone resorption and formation specially postmenopausal female