ABNORMAL INCREASES IN URINARY ALBUMIN EXCRETION DURING PREGNANCY IN IDDM WOMEN WITH PREEXISTING MICROALBUMINURIA

We compared urinary albumin excretion during and after pregnancy in 30 insulin-dependent diabetic (IDDM) women with normoalbuminuria and in 12 IDDM women with microalbuminuria (> 15 mu g.min(-1)) prior to conce ption. There was a 6.7-fold increase in the urinary albumin excretion up until the third trimester in the women with pre-existing microalbum inuria, compared with a 3.8-fold increase in the normoalbuminuric wome n. In both groups of patients the urinary albumin excretion reached a peak during the third trimester with 492 +/- 404 mu g.min(-1) in the m icroalbuminuric women vs 43 +/- 36 mu g.min(-1) in the normoalbuminuri c women (p < 0.0005). Two women from each of the groups developed ecla mpsia with diastolic blood pressure over 90 mmHg, mild or moderate oed ema and macroproteinuria. Four of the pregnant women with pre-existing microalbuminuria showed a transient nephrotic syndrome (33.3 %) with protein excretion over 3 g in 24-h urine samples during the third trim ester. In contrast, this was not observed in any of the normoalbuminur ic women (p < 0.05). Within 12 weeks after delivery the urinary albumi n excretion rates dropped to the pre-conception values in both patient groups. Renal function remained normal during pregnancy in both of th e groups, with a physiological increase in creatinine clearance up unt il the third trimester (26 % increase in the normoalbuminuric women vs 22 % in the microalbuminuric women). In conclusion, the effect of pre gnancy on the urinary albumin excretion in diabetic women with preexis ting microalbuminuria is an exaggeration of the increase of albuminuri a in diabetic women with normoalbuminuria; normalization occurs within 12 weeks after delivery in all cases. This enhancement of the albumin excretion in the microalbuminuric women cannot be explained by a larg er increase in the hyperfiltration during pregnancy.