Bone Mineral Content before and after Intestinal Bypass Operation in Obese Patients

Abstract

Bone mineral loss after intestinal bypass operation was investigated. Bone mineral content (BMC) was measured by 2-dimensional scanning photon absorptiometry on the distal part of the forearm in 23 consecutive patients who had undergone intestinal bypass operation for obesity. Eleven patients (group 1) were investigated before and 12 mo. after operation and 12 (group 2), who were operated on 2-7 yr earlier, were investigated 2 times at an interval of 12 mo. No patient received therapeutic Ca or vitamin D supply. The predominant biochemical findings postoperatively were: decreased serum values of Ca, Mg, albumin and total protein. There was no change in inorganic phosphate or alkaline phosphatase. Mean BMC was normal in the 2 groups postoperatively as well as in group 1 before operation. These was no significant change in mean BMC during 12 mo. of observation. In BMC measurements on extremely obese subjects, a correction for the excessive fat layer on the forearm was necessary because of different attentuation properties of fat and soft tissues. Neglect of this problem will give a systematic underestimation of BMC and may lead to false conclusions in cross-sectional as well as longitudinal studies.