Mihmanli M, et al. - This study was designed to determine the effects of Laparoscopic sleeve gastrectomy (LSG) on intact parathyroid hormone (iPTH), 25-OH-vitamin-D3 (vitD), calcium (Ca), phosphorus (P), alkaline phosphatase (ALP), and albumin levels. Despite normal preoperative serum levels of iPTH, vitD, Ca, P, vitB12, ALP, and albumin, severe vitD insufficiency requiring high-dose vitD replacement could develop in morbidly obese patients postoperatively. Instead of iPTH and vitD, which are expensive to measure, it seemed that suggest ALP serum level could be a good indicator to monitor calcium metabolism, as it was correlated with iPTH levels.