Effect of ascites on bone density measurement in cirrhosis

Cirrhosis is an independent risk factor for the development of osteoporosis. The presence of ascites in patients with cirrhosis may affect the accuracy of bone density measurement in the spine. Twenty cirrhotic patients had bone mineral density (BMD) measurements of the lumbar spine, femoral neck, hip, and total body using dual-energy X-ray absorptiometry (DXA; Lunar Prodigy) before and after large-volume paracentesis. To establish short-term precision of DXA measurement, 28 healthy adults also had duplicate BMD measurements on the same day. After paracentesis (6.4 +/- 2.0 L), there was a significant increase in the spine BMD of 4.2% (p = 0.003) and in the total hip BMD of 1.3% (p = 0.002), but there was no change in the femoral neck or total body. No significant differences (p > 0.1) were seen in duplicate BMD measurements at any site among the healthy cohort. Within-patient changes in spine (p = 0.001) and total hip (p = 0.001) BMD measurements were significantly greater in patients with ascites than in the healthy cohort. These changes in BMD measurements were not associated with age, gender, amount of fluid removed, or time interval between measurements. These results suggest that ascites cause a fluid artifact in the soft tissue and bone interface that can falsely lower BMD measurements, particularly in the spine.