Isoenzyme A and UrinaryN-Acetyl-β-D-Glucosaminidase Activity in Normal Pregnancy

Abstract

Objectives: Urinary N-acetyl-β-D-glucosaminidase (NAG) activity has been found to increase during normal uncomplicated pregnancy and such behavior could limit the diagnostic value of this enzyme for detection of subclinical tubular injury. The aim of this study was to evaluate urinary NAG activity and isoenzyme A in normal pregnant women at 30th week of pregnancy and in healthy women, to discriminate between physiological and lesional enzymuria. Design and methods: Enzyme activities in first morning fasting urine samples from 20 nonpregnant control and 20 normal pregnant women at 30th gestational week were evaluated by fluorometric methods. Results: Both total and isoenzyme A activity was significantly higher ( p < 0.01) in urines of normal pregnant women compared with control urines, whereas ratio between these two parameters was significantly lower ( p < 0.001). Conclusions: The increase of urinary NAG activity during normal uncomplicated pregnancy appears to be characterized by a prevalent increase in isoenzyme A form, a finding associated with functional (not lesional) enzymuria. The fluorometric assays may represent a simple and rapid method to evaluate whether increase in urinary NAG activity represents a renal physiological adaptation during pregnancy.

Association Between Pulse Wave Velocity and a Marker of Renal Tubular Damage (N‐Acetyl‐β‐D‐Glucosaminidase) in Patients Without Diabetes

“…One explanation for non‐zero is the necrosis and apoptosis of renal tubular epithelial cells, but likely other explanations for this exist as well. NAG exist in human tissues and body as two major isoenzymic forms (A and B), and several minor forms (I1, I2, As, and P), which are distinguished according to their different charge characteristics by chromatography on diethylaminoethyl cellulose . The possibility to evaluate the different isoenzymatic profile of NAG has led to the notion of so‐called functional enzymuria mainly linked to preferential urinary excretion of A isoenzyme, and so‐called lesional enzymuria with preferential urinary release of B isoenzyme .…”

Reference Intervals of Renal Function Set Established for Healthy Pregnant Women

“…In the 1960s, when pregnancy was reported, NAG mainly existed in the decidual and chorionic cells of the placenta. Serum NAG began to increase after four months of gestation, especially in isoenzyme A form [25] which was parallel to the development of the placenta and the histological changes of the placental connective tissue after 4 months of gestation [26]. NAG was released to the maternal circulation mainly from the decidua and only partly from the amnion.…”

Hafif preeklampside üriner N-asetil-β-D-glukozaminidaz (NAG) ve renal tübüler hasar

“…In pregnant women, urinary excretion of enzymes and other proteins varies significantly 11 . As changes in enzyme excretion may be related to the adaptation of renal functions to pregnancy, different values should be determined for the excretion of enzymes.…”