[Studies on reflux nephropathy--renal tubular and glomerular damage evaluated by various urinary indices]

Measurements were performed on beta 2-microglobulin (beta 2-MG), alpha 1-microglobulin (alpha 1-MG), N-acetyl-beta-D-glucosaminidase (NAG) as indices of renal tubular damage and microalbumin as an index of renal glomerular damage in 204 cases with primary vesicoureteral reflux (VUR). Investigations were made on the relationship between each index and extent of renal cortical damage from the findings of 99mTc-dimercapto-succinic acid (DMSA) renoscintigraphy, and also on the changes of each index before and after antireflux operation. At the first examination, high values of urinary beta 2-MG, alpha 1-MG, NAG and albumin were noted in 36%, 40%, 50% and 34% of cases with VUR respectively. Almost all the cases with high indices values before the operation showed improvement in those values accompanied with disappearance of VUR after the operation. These findings suggest that renal tubular and glomerular damage were induced by the sterile reflux itself. High values of urinary indices were confirmed in 16% (beta 2-MG), 40% (alpha 1-MG), 27% (NAG) and 32% (albumin) cases after a lapse of 2 years or longer since antireflux operation or spontaneous disappearance of VUR. In some of these cases indices values showed some improvement but have not returned to normal levels, and in other cases indices were within normal limits preoperatively but turned out to be high levels during the observation period even after the disappearance of VUR. Most of these cases were accompanied with severe cortical damage of unilateral or bilateral kidneys on DMSA renoscintigraphy. Based on these findings, we suggest that overload to residual nephron, caused by reduced mass of functional nephron, is playing an important role on raising the values of various urinary indices.