Does paracentesis of ascites influence measurements of bone mineral or body composition by dual-energy x-ray absorptiometry?

Measurements of bone mineral content (BMO) and density (BMD) by dual-energy x-ray absorptiometry (DXA) may be affected by changes in soft tissue overlying bone. Furthermore, the accuracy error for body composition determined by DXA may be high in the trunk region due to the complex bone geometry. Our objective was to evaluate the impact of paracentesis on measurements of bone mineral and body composition by DXA. DXA (Norland XR-36; Norland, Fort Atkinson, WI) scans were performed in six patients with cirrhosis of the liver before and after treatment of ascites by paracentesis. There were no significant differences in the spinal BMC (change [delta] = 0.04%) and BMD (delta = -0.9%) (P > .05), nor in total body BMC ([TBBMC] delta = 1.9%) and BMD ([TBBMD] delta = 0.4%) (P > .05). The median volume of ascites drained (6.8 L; range, 1.6 to 14.7) was not significantly different from the median change in total (5.8 kg; range, 2.0 to 16.1) or trunk lean tissue mass ([LTM] 5.8 kg; range, 1.9 to 11.9) (P > .05). The changes in body weight correlated with the changes in trunk LTM (r = .93, standard error of the estimate [SEE] = 1.8 kg, P = .007). Total and regional fat mass were not changed significantly by the paracentesis. We conclude that measurements of total body and spinal bone mineral by DXA are unaffected by large changes in the soft tissue composition and height of the trunk. Furthermore, the change in body composition induced by ascites drainage was accurately determined as a change in total body and trunk LTM on a group level.