Diurnal variation in excretion of N-acetyl-beta-glucosaminidase during pregnancy: Implications for the prediction of pre-eclampsia

Significant differences in urinary excretion of N-acetyl-beta-glycosaminida se (NAG) were observed between nulliparous and multiparous patients and bet ween fasted and nonfasted individuals. No significant difference was observ ed between patients with normal and those with abnormal glucose tolerance. Multiple regression analysis confirmed that the significant independent det erminants of NAG/creatinine ratio were age, parity, gestation and fasting s tate. Significant diurnal variation in urinary NAG/Cr ratio was observed, t he highest levels being recorded in early morning fasting specimens, fallin g in each postprandial specimen and beginning to rise again by midnight. Th e urinary NAG/Cr ratio is influenced by fasting, parity, gestation and age. More consistent results for prediction of pre-eclampsia are therefore like ly to be obtained using fasting (early morning) urine specimens and adjusti ng cut-off criteria for the other factors.