The enzymatic kinetics of urinary N-acetyl-β-glucosaminidase was studied in healthy newborns and children and in a group of infants with renal diseases. Apparent Km values did not differ in healthy and sick children but were 50% lower in neonates (P <0.01). Vmax values were higher in patients with renal diseases or on treatment with aminoglycosides, and in neonates. This study confirms that urinary NAG is a useful indicator of a renal injury and suggests that a different isoenzyme is excreted in large amounts early in life. The necessity of diluting urines before assay in order to reduce the inhibition caused by an unidentified dialyzable native substance is discussed and an internal standard method is proposed.
ASJC Scopus subject areas