Markers of tubular damage in pre-eclampsia.

Background: The aaim of this study is to investigate the tubular damage markers in pre-eclampsia and in pregnancy induced hypertension (PIH).
Methods: This transversal study involved 111 women admitted to the Department of Obstetric and Gynaecology, University Hospital, Padua (Italy) and was conducted from the 24th week until delivery: 23 had normal pregnancies, 54 manifest pre-eclampsia, and 34 manifested pregnancy-induced hypertension (PIH) without superimposed pre-eclampsia. The following laboratory tests were performed: U-alpha 1 microglobulin, U-NAG, uric acid and microalbuminuria. The four groups were compared using the Mann-Whitney test and the Kruskall-Wallis test for multiple comparisons. A value of p < 0.05 was considered as statistically significant.
Results: As for the markers of tubular damage, the values for urinary NAG were significantly lower in the control group (0.97 U/mmol Creat) than in the pre-eclampsia group (2.89 U/mmol Creat), and the PIH group (2.12 U/mmol Creat) (p < 0.01). Values for urinary alpha 1-microglobulin were higher in the pre-eclampsia group (4.03 U/mmol Creat) than in the control (0.74 U/mmol Creat), and PIH groups (1.88 U/mmol Creat) (p < 0.01). As for the markers of glomerular damage, the values of microalbuminuria were higher in the pre-eclampsia group (134 micrograms/min) than in the control (9.4 micrograms/min), and PIH groups (10 micrograms/min), (p < 0.05). Uric acid, the marker of glomerular and tubular damage, was higher in the pre-eclampsia group (0.27 mmol/L) than in the control (0.20 mmol/L), and PIH groups (0.24 mmol/L), (p < 0.05).
Conclusions: In pre-eclampsia there is a tubular and glomerular damage to point out by an increased urinary excretion of NAG. In pre-eclampsia, an increase of urinary alpha 1-microglobulin excretion may be considered to be partly due to the overloading of the tubule and partly due to a mixed glomerular and tubular lesion.