Bone Metabolism After Laparoscopic Gastric Bypass Surgery (BABS) (BABS)

Phase 2 Study of Patients Undergoing Bariatric Surgery (Laparoscopic Gastric Bypass) and Evaluation of Bone Metabolism With/Without Vitamin D/Calcium Supplementation

Bariatric surgery leads to rapid weight loss in female and male patients. Less data are available about its impact on bone metabolism. The aim of this study is the investigation of changes in bone mineral density,bone histomorphometric changes, serum bone turnover markers and changes in body fat and muscle composition in patients after laparoscopic gastric bypass surgery.

Obese female and male adult patients eligible for laparoscopic gastric bypass surgery according to the national Austrian guidelines will be included in this study upon request and after patient approval. Baseline data collection and quarterly follow up visits are planned to investigate the changes in bone mineral density and body composition measured by dual energy X-ray absorptiometry as well as the evaluation of serum bone turnover markers of bone formation and resorption. After surgery subjects will be randomized into two groups: Daily oral calcium (500mg) and weekly vitamin D3 supplementation (16.000 IU calciferol)or no supplementation of calcium and calciferol. A sub-study (approximately 15% of study population) with transiliac bone biopsies will also be performed to investigate histomorphometric and histologic changes in bone (biopsy baseline and after 24 months). The planned duration of the study is 24 months for each subject. Serum bone turnover markers will be collected every 3 months, dual energy X-ray absorptiometry measurements will be performed every 6 months.

Evaluation of Expected Bone Loss After Bariatric Surgery, Possible Prevention of Bone Loss After Surgery by Calcium and Vitamin D Supplementation

All subjects will receive calcium/vitamin D supplementation after laparoscopic bariatric gastric bypass surgery as follows: daily: 500 mg oral calcium (calcium carbonate) weekly: 16.000 IU oral vitamin D3 (calciferol)

All subjects will not receive calcium/vitamin D supplementation after laparoscopic bariatric gastric bypass surgery.

Dual energy X-ray absorptiometry (DXA) measurements of bone mineral density at lumbar spine, hip, calcaneus and total body will be performed at baseline and every six months for a period of 24 months. Differences will be evaluated on the outcome with/without daily calcium (500mg) and weekly vitamin D (16.000 IU calciferol) supplementation

Evaluation of changes of serum bone turnover markers in obese patients after laparoscopic bariatric surgery

Fasting serum markers of bone formation and bone resorption will be evaluated: Calcium, 25-OH-vitamin D3, intact parathyroid hormone, beta-crosslaps, type-1-procollagen, bone specific alkaline phosphatase, osteocalcin, sclerostin, osteoprotegerin, cathepsin-K, fibroblast factor 23, lipoprotein A, dickkopf 1 Differences will be evaluated on the outcome with/without daily calcium (500mg) and weekly vitamin D (16.000 IU calciferol) supplementation

Evaluation of histomorphometric and histologic changes in obese patients after laparoscopic bariatric surgery

Transiliac bone biopsies will be performed in a approximately 15% of patients at baseline and after 24 months. The following parameters will be measured: bone volume (BV/TV), bone surface (BS/BV), osteoblast surface (OS/BS), trabecular number (TbN), trabecular thickness (TbTh, trabecular separation (Tb.sp), mineralized surface (MS/BS), mineral apposition rate (MAR) Differences will be evaluated on the outcome with/without daily calcium (500mg) and weekly vitamin D (16.000 IU colecalciferol) supplementation

Inclusion Criteria: body mass index >35 female and male patients age 18 - 65 years eligible for laparoscopic gastric bypass surgery according to the Austrian national guidelines Exclusion Criteria: any history of malignancy except basalioma any prior antiresorptive treatment any prior calcium or vitamin D supplementation any secondary disease affecting bone metabolism

Muschitz C, Kocijan R, Haschka J, Zendeli A, Pirker T, Geiger C, Muller A, Tschinder B, Kocijan A, Marterer C, Nia A, Muschitz GK, Resch H, Pietschmann P. The Impact of Vitamin D, Calcium, Protein Supplementation, and Physical Exercise on Bone Metabolism After Bariatric Surgery: The BABS Study. J Bone Miner Res. 2016 Mar;31(3):672-82. doi: 10.1002/jbmr.2707. Epub 2015 Sep 30.