Urinary excretion of N-acetyl-beta-D-glucosaminidase and alanine aminopeptidase during pregnancy.

The assay of enzyme activity in urine seems a reliable and safe method to monitor different kidney diseases. However, its use in pregnant patients might be limited by the modifications of kidney function during pregnancy. The aim of the present study was to evaluate the trend of excretion of the lysosomal enzyme N-acetyl-beta-D-glucosaminidase (NAG) and the brush border enzyme alanine aminopeptidase (AAP) during uncomplicated pregnancies. NAG excretion showed a significant increase (P less than 0.001) throughout pregnancy, while no significant modification of AAP levels was demonstrated. These data support the hypothesis that the two enzymes are excreted into the urine through different mechanisms and might constitute markers for different pathological events. As the increase of NAG excretion may be related to the kidney functional adaptation to pregnancy, different cut-off limits must be established in this period.