MINERAL METABOLISM: Edited by Aline Martin and Tamara IsakovaLessons from rodent gastric bypass model of enteric hyperoxaluriaKwenda, Elizabeth P.; Rabley, Andrew K.; Canales, Benjamin K.Author Information Department of Urology, College of Medicine, University of Florida, Gainesville, Florida, USA Correspondence to Benjamin K. Canales, MD, MPH, Department of Urology, University of Florida, 1600 SW Archer Road, PO Box 100247, Gainesville, FL 32610-0247, USA. Tel: +1 352 273 8236; fax: +1 352 273 7515; e-mail: firstname.lastname@example.org Current Opinion in Nephrology and Hypertension: July 2020 - Volume 29 - Issue 4 - p 400-406 doi: 10.1097/MNH.0000000000000613 Buy Metrics Abstract Purpose of review The aim of the article is to review studies on bone health and oxalate metabolism/therapeutics in the obese rodent model of Roux-en-Y gastric bypass (RYGB) and examine pathways to decrease procedural morbidity. Recent findings Compared with controls, RYGB rodents have up to 40-fold more fat in their stool (steatorrhea) which positively correlates to increased urinary oxalate. These unabsorbed intestinal fatty acids bind calcium and prevent gut calcium oxalate formation, increasing soluble luminal oxalate availability and absorption (enteric hyperoxaluria). When intraluminal fecal fat exceeded about 175 mg/24 h in our model, more paracellular and transcellular oxalate transport across the distal colon occurred. Increasing dietary calcium and colonization with Oxalobacter formigenes reduced hyperoxaluria, whereas vitamin B6 supplementation did not. RYGB animals, when severely calcium deficient, had bone mineral density loss that could not be rescued with vitamin D supplementation. Summary The findings of hyperoxaluria, steatorrhea, and decreased bone mineral density are seen in both human and rodent RYGB. Our model suggests that a low-fat, low-oxalate diet combined with calcium supplementation can decrease urinary oxalate and improve skeletal bone health. Our model is a useful tool to study renal and bone RYGB effects. Studies of longer duration are required to further evaluate mechanisms of disease and durability of therapeutics. Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.