URINARY ALBUMIN EXCRETION IN NORMAL-PREGNANCY AND PREGNANCY-INDUCED HYPERTENSION

We measured the urinary excretion of albumin in 67 healthy primigravidae, at monthly intervals, from 16 to 36 weeks of gestation and 12 weeks postpartum. Of the 67 primigravidae, 55 completed a normal pregnancy and 12 developed pregnancy-induced hypertension. In the latter group, an additional measurement of urinary albumin excretion was performed at 24 weeks postpartum. The aims of the study were: to look for changes of urinary albumin excretion during the progression of normal pregnancy, to assess if microalbuminuria could be an early feature of pregnancy-induced hypertension; to evaluate the effects of physical activity on the excretion of albumin in normal pregnancy and pregnancy-induced hypertension. In contrast with glomerular hyperfiltration and increased urinary total protein, two recognized characteristics of the pregnant state, we found that normal primigravidae, during the day, excrete significantly less albumin (p between < 0.01 and < 0.001) in comparison with the postpartum period and nonpregnant women. Normal primigravidae, as a group, showed parallel changes of urinary albumin excretion and diastolic blood pressure throughout pregnancy and postpartum, suggesting an important physiologic role of hemodynamic factors in regulating glomerular permeability to albumin. The daytime urinary albumin excretion in patients developing pregnancy-induced hypertension was significantly higher (p between < 0.005 and < 0.001) than in normal pregnancy from the 28th gestational week onwards. The increased urinary albumin excretion preceded the onset of hypertension and tended to persist long after blood pressure had returned to normal levels. We conclude that the pregnant state changes the pattern of urinary protein excretion in normal primigravidae, and that the overt clinical manifestations of pregnancy-induced hypertension are preceded and followed by long-lasting phases of increased urinary albumin loss.