Sensitivity of residual nephrons to high dose furosemide described by diuretic efficiency.

Ten haemodialysis (HD) patients with a median residual creatinine clearance (CLCR) of 1.9 ml.min-1 x 1.73 m-2 (range 0.6-5.3) were treated with oral furosemide (F) 2.0 g. Overall-efficiency (O-E, daily sodium excretion/total urinary F) and total-efficiency (delta-E, increase in daily sodium excretion/total urinary F) were measured on the last 24 hours of each interdialysis interval. In addition, O-E was measured during the complete interdialysis interval in 10 HD patients with a median CLCR of 5.6 ml.min-1 x 1.73 m-2 (range 0.7-6.8) treated for 1 year with a fixed oral dose of F between 250-1000 mg (median 625 mg). In the short study the median O-E was 10.6 mmol.mg-1 (range 1.9-22.0) and delta-E 6.2 mmol.mg-1 (range 1.3-11.2). The fractional excretion of sodium FENa was significantly increased from 9.6% (range 4.1-22.9) to 27% (range 14.6-56.2) during F treatment. A positive correlation was found between the basal FENa and delta-E. In the long-term study median O-E was 6.4 mmol.mg-1. O-E and FENa showed no change over time although median RCC decreased from 5.6 to 1.9 ml.min-1 x 1.73 m-2 and median F excretion from 11.8 to 7.5 mg per day. It can be concluded that diuretic efficiency in haemodialysis patients is dependent on FENa and the state of hydration during the interdialysis interval.