Prevalence of elevated alkaline phosphatase levels among post-bariatric surgery patients

Little is known about the prevalence of elevated alkaline phosphatase in post-bariatric surgery patients due to under-utilization of this test after surgery. Elevated alkaline phosphatase levels are caused by hepatobiliary disease or bone resorption, which can lead to gallstones and osteoporosis. Early, post-operative measurement of alkaline phosphatase can prevent complications, thus reducing morbidity and overall healthcare costs. The purpose of this study was to determine the prevalence of elevated alkaline phosphatase levels among post-operative bariatric surgery patients.

This was a retrospective study of patients 18 years or older, who underwent laparoscopic sleeve gastrectomy (LSG) at a Midwestern Weight Management Clinic between January 1, 2002 and December 31, 2020. Alkaline phosphatase levels, weight, body mass index (BMI), gamma-glutamyl transferase (GGT), parathyroid hormone (PTH), calcitriol, and calcitonin, vitamin D and multivitamin supplementation were measured at baseline, 3, 6, and 12 months post-surgery.

Two hundred thirty patients with mean age of 47 years and BMI of 44.6 were included with 80.9% (n = 186) female. Alkaline phosphatase was elevated relative to baseline for 36.1% of patients (n = 52) at 3 months post-surgery, 42.4% of patients (n = 56) at 6 months, and 43.3% of patients (n = 45) at 12 months (p < 0.001). There were six cases of documented cholelithiasis post-surgery.

A significant proportion of participants experienced elevations in alkaline phosphatase following surgery, indicating that the prevalence of gallbladder pathology and bone resorption may be higher than previously thought. This merits additional investigation into these complications post-operatively to determine prevalence and avoid excess morbidity.