N-acetyl-beta-D-glucosaminidase and beta 2-microglobulin: Prognostic markers in idiopathic nephrotic syndrome

Increased urinary excretion of N-acetyl-beta-D-glucosaminidase (NAG) and be ta 2-microglobulin (beta 2M) is considered a marker of tubulo-interstitial disease. This study assessed urinary excretion of NAG and beta 2M in childr en with nephrotic syndrome (NS), 14 with cortico-sensitive nephrotic syndro me (CSNS), five with cortico-resistant NS (CRNS) and 30 healthy controls ma tched for sex and age. At onset urinary excretion of NAG was significantly higher in children with CSNS than controls (p=0.0001) but during remission values were superimposable. Conversely in CRNS at onset urinary excretion o f NAG and beta 2M was significantly higher than CSNS and remained unchanged at the end of steroid treatment (p < 0.05 and p < 0.01). Urinary NAG value s in CSNS were correlated with proteinuria (r = 0.63), serum total proteins (r = -0.54), serum albumin (r = -0.55) and serum cholesterol (r = 0.67). These data suggest that urinary excretion of NAG and beta 2M may be useful as a marker of tubular dysfunction in nephrotic syndromes which often chara cterises cortico-resistant patients.