Objective : AACE/TOS/ASMBS guidelines recommend monitoring serum 25-hydroxyvitamin D levels preoperatively and post-operatively and to titrate vitamin D supplementation to maintain a level of at least 30 ng/mL to minimize the risk of metabolic bone disease following Roux-en-Y gastric bypass (RYGB). There have been few studies to evaluate the adherence to this and the success rate in maintaining adequate 25-hydroxvitamin D levels in long term follow up in clinical practice. We aimed to study the frequency of vitamin D monitoring and the effects of race and time following surgery on serum 25-hydroxyvitamin D at our academic medical center.
Methods : We reviewed the electronic medical records of adult patients who had undergone bariatric surgery procedures at Boston Medical Center between 2004 and 2017 (N=3346). Post-operative clinical and laboratory data were extracted by the Clinical Data Warehouse. We limited our analysis to African American, Caucasian, and Hispanic subjects who had RYGB. Subjects were excluded if they were not followed for at least one year after surgery to evaluate the long-term serum changes after surgery. We used linear mixed models (treating subjects as a random effect) to examine the fixed effects of race, sex, time from surgery, age, and body mass index (BMI) on 25-hydroxyvitamin D. Analyses were performed were performed in SAS Studio 3.71.
Results : We identified 1598 subjects who met our criteria. Our sample included 393 African Americans (24.6%), 408 Hispanics (25.5%), and 797 Caucasians (49.9%). The mean age was 41.9 years (range 18 – 71). The mean duration of follow up was 4.9 years after surgery. There were 292 assays for 25-hydroxyvitamin D. Linear mixed model analyses showed a significant effect of race (p=0.0034) and a significant effect of time (p=0.015). The adjusted marginal mean 25-hydroxyvitamin D was 24.2 ng/mL for African Americans (p = 0.0017 vs. Caucasians, p = 0.72 vs. Hispanics), 25.5 ng/mL for Hispanics (p = 0.014 vs. Caucasians), and 34.5 for Caucasians.
Discussion : Following RYGB, African Americans and Hispanics had persistently lower 25-hydroxyvitamin D levels than Caucasians. Racial differences in vitamin D binding protein and bioavailable vitamin D have been described and may contribute to this outcome. The implementation of standardized post-operative order sets may improve the frequency of monitoring for vitamin deficiencies.
Conclusion : Vitamin D deficiency is common and persists for several years after RYGB. More research is needed to study absorption of and adherence to vitamin D, especially in AA and Hispanic patients after RYGB. Protocols to help optimize vitamin D supplementation and adherence in this high-risk population are needed.
Dylan Thomas– Endocrinology Fellow, Boston Medical Center / Boston University, Boston, Massachusetts
Caroline Apovian– Professor of Medicine and Pediatrics, Boston University
Liqun Yu– Lab Technician, Boston Medical Center
Wendy Anderson– Senior Surgical Weight-Management Dietician, Boston Medical Center
Donald Hess– Chief, Section of Bariatric Surgery, Boston Medical Center
Brian Carmine– Assistant Professor of Surgery, Boston University School of Medicine
Nawfal Istfan– Associate Professor of Medicine, Boston University School of Medicine
Boston Medical Center / Boston University
Dylan Thomas is a PGY6 Endocrinology Fellow at Boston University / Boston Medical Center.
Professor of Medicine and Pediatrics
Caroline M. Apovian, M.D., FACP, FTOS, DABOM, is Professor of Medicine and Pediatrics, in the Section of Endocrinology, Diabetes, and Nutrition at Boston University School of Medicine, USA. She is also Director of the Center for Nutrition and Weight Management at Boston Medical Center, USA. Dr. Apovian has given over 150 invited lectures nationally and internationally and currently serves as President of The Obesity Society (TOS) for 2017-18.
Boston Medical Center
Liqun Yu, MS is a lab technician at BMC.
Senior Surgical Weight-Management Dietician
Boston Medical Center
Wendy Anderson, RDN, LDN, MS is a Senior Surgical Weight-Management Dietician at Boston Medical Center
Chief, Section of Bariatric Surgery
Boston Medical Center
Donald Hess, MD is a bariatric surgeon and the Chief of the Section of Bariatric Surgery at Boston Medical Center and Director of Bariatric Surgery Program. He is also an Assistant Professor of Surgery at Boston University School of Medicine
Assistant Professor of Surgery
Boston University School of Medicine
Brian Carmine is a bariatric surgeon and an Assistant Professor of Surgery at Boston University School of Medicine.