Blood pressure, renal functional and structural changes, in normal and preeclamptic pregnancy

Sammanfattning: The kidneys play a pivotal role in the adaptive physiology of the pregnant woman, presenting some changes at term similar to the changes found in preeclampsia – a state of increased risk of fetal and maternal morbidity and mortality. The aim of these investigations was to explore possible similarities in blood pressure regulation, renal function and structure in normal term and preeclamptic pregnancy, to ascertain whether both conditions in fact are different degrees of an adaptive process in reaction to pregnancy. Blood pressure changes were studied in 600 normal pregnancies and in 166 women through their first three pregnancies, revealing an influence of gestational age, ethnicity, parity, baseline BMI and smoking habits - factors similar to known risk factors for preeclampsia. Renal functional changes were studied in 48 pregnant and 12 non-pregnant women, revealing a size- and/or charge-dependant alteration in the filtration process in pregnant women at term compared to non-pregnant women, the glomerular filtration further impaired in preeclampsia. Renal structural changes were studied in 36 hypertensive pregnant women and 12 healthy term pregnant women, and the typical preeclamptic lesion, glomerular endotheliosis, was found not only in all hypertensive patients but also in seven of the twelve controls. Clinically undetected renal disease was not diagnosed in any of the women, leaving very few clinical indications for the renal biopsy in pregnancy. This opinion could be underscored by the findings that cystatin C levels in pregnancy, not only reliably reflected the glomerular filtration rate, but also correlated significantly with estimated glomerular volume and the degree of endotheliosis. Serum cystatin C consequently seemed to closely reflect the renal functional and structural changes, which are believed to lead to increased blood pressure levels and urinary excretion of albumin, and may thus function as a marker for the stage of the transition between normal adaptive renal changes at term and preeclampsia.