Value of urinary endothelin-1 in patients with primary vesicoureteral reflux

By using a radioimmunoassay specific for endothelin-1 (ET-1), we measured urinary excretion of ET-1-like immunoreactivity (LI) in 63 spot urine samples of 48 patients with primary vesicoureteral reflux (VUR). And also, urinary excretion of N-acetyl-beta-D-glucosaminidase (NAG), beta 2-microglobulin (beta-2-MG), microalbumin (Alb) and creatinine (Cr) were measured. There was no significant correlation in any of the pairs ET-1 and NAG, ET-1 and beta 2-MG, and ET-1 and Alb. Comparing the grade of reflux according to the International Classification with urinary ET-1, urinary ET-1/Cr levels in patients with grade 2, 3 and 4 VUR were higher than normal, and the ratio of more than normal urinary ET-1/Cr increased in proportion to the grade of reflux, but it conversely decreased in grade 5. In conclusion, urinary ET-1 may be an indicator of renal tubular injury in patients with primary VUR, and its meaning may be different from conventional urinary parameters.