Utilization of Preoperative Patient Factors to Predict Postoperative Vitamin D Deficiency for Patients Undergoing Gastric Bypass

Vitamin D deficiency occurring after gastric bypass procedures can predispose patients to calcium and parathyroid hormone (PTH) level abnormalities. The aim of the study is to identify preoperative patient risk factors for postoperative vitamin D deficiency. We retrospectively reviewed patients who underwent Roux-en-Y gastric bypass procedures between 2005 and 2006. Patient demographics, laboratory values of calcium, vitamin D, and PTH were followed at quarterly intervals for 1 year. One hundred forty-five patients were included in the study. The mean age for the group was 44 years with an average body mass index of 49.5 kg/m(2). Eighty-six percent of patients were female and 23% was African-American. Forty-two percent of the patients had vitamin D deficiency (< 20 ng/mL) either preoperatively or at year 1. The mean calcium levels decreased from 9.39 to 9.16 mg/dL (p < 0.001) while the mean PTH levels increased from 25.7 to 43.9 ng/mL (p < 0.001). A logistic regression model recognized preoperative vitamin D levels, race, and bypass limb length to be the only significant factors (p < 0.05) for postoperative vitamin D deficiency. It is important to recognize patients who are at risk for vitamin D deficiency before surgery so that early intervention could be in place to minimize further postoperative deficiency.