Over-estimation of glomerular filtration rate by single injection [51Cr] EDTA plasma clearance determination in patients with ascites

The total plasma (Clsub(t)) and the renal plasma (Clsub(r)) clearances of [51Cr]EDTA were determined simultaneously in nine patients with ascites due to liver cirrhosis. Clsub(t) (mean 78 ml/min, range 34-115 ml/min) was significantly higher than Clsub(r) (mean 52 ml/min, range 13-96 ml/min, P<0.005). The ascitic fluid-plasma activity ratio of [51Cr]EDTA increased throughout the investigation period (5 h). The results suggested that [51Cr]EDTA equilibrates slowly with the peritoneal space which indicates that Clsub(t) will over-estimate the glomerular filtration rate by approximately 20 ml/min in patients with ascites. To assess glomerular filtration rate in presence of ascites, the renal plasma clearance of [51Cr]EDTA should be used instead of the total plasma clearance. (author)