Increased excretion of N-acetyl-beta-D-glucosaminidase and beta(2)-microglobulin in gestational week 30

Background: Little is known about when the urinary excretion of a combinati on of N-acetyl-beta -D-glucosaminidase (NAG) and beta (2)-microglobulin (be ta (2)MG) concentration [relative to creatinine (Cr)] reaches maximal value s during uncomplicated normotensive pregnancy. This study was thus designed to analyze when urinary excretion of biochemical parameters was increased during normotensive pregnancy. Methods: NAG, beta (2)MG, total protein, alb umin, and Cr were simultaneously measured in random (untimed) midstream uri ne samples from 22 healthy nonpregnant women and from 82 normotensive pregn ant women (22 in gestational week 20, 25 in week 30, and 35 in week 37). Re sults NAG/Cr and beta (2)MG/Cr ratios were significantly higher (P < 0.01-0 .05) in the normotensive pregnant women in gestational week 30 than in the nonpregnant control subjects and normotensive pregnant women in gestational week 20. The NAG/Cr and <beta>(2)MG/Cr ratios showed maximal values in ges tational week 30. The total protein/Cr ratio was significantly higher in ge stational weeks 20, 30, and 37 than in the control subjects. The albumin/Cr ratio was significantly higher in women in gestational week 30 and 37 than in women in gestational week 20 and in the control subjects. Conclusions: The excretion of both NAG and P,MC relative to Cr was increased and showed the maximal values in gestational week 30 during normotensive pregnancy. Th e increase in a tubular enzyme (NAG) might be caused by renal tubular damag e, and that in a molecular weight protein (beta (2)MG) might result from de creased renal tubular reabsorption. These findings suggest that renal tubul ar damage and reabsorption dysfunction were increased in gestational week 3 0.