Renin-Angiotensin-Aldosterone Profiles in Pregnant Women With Chronic Hypertension

Abstract

Pregnant women with chronic hypertension are at risk for increased blood pressure and superimposed preeclampsia (SPE) in late pregnancy. Alterations in the renin-aldosterone system are a feature of normal pregnancy; however, their role in chronic hypertension with and without SPE is less clear. We performed a prospective, longitudinal trial of 108 women with chronic hypertension and measured plasma renin activity (PRA), 24-hour urine sodium, urine potassium, and urine aldosterone (Ualdo) at 12, 20, 28, and 36 weeks and postpartum. SPE developed in 34% of pregnancies. PRA was lower in women who developed SPE at weeks 28 (5.99 versus 6.22 ng/mL per hour; <0.001) and 36 (5.71 versus 7.74 ng/mL per hour; =0.002). Ualdo was lower in women with SPE compared with those without SPE at 28 weeks (59.6 versus 81.3 μg/d;=0.039). Mean arterial pressure was inversely related to both PRA (=-0.23; <0.0001) and Ualdo (=-0.11; =0.029). PRA and Ualdo were positively associated with each other (=0.5327; <0.0001) after adjusting for urine potassium, urine sodium, serum potassium, and mean arterial pressure. PRA and Ualdo were lower in women of black race compared with other racial groups (<0.001). Our results demonstrate that in women with chronic hypertension PRA and Ualdo increase in early pregnancy and subsequently decrease in women who develop SPE. These findings are consistent with the hypothesis that sodium retention may contribute to the elevation in blood pressure in SPE.

Hypertension in a Pregnant Patient: How I Treat

“…Levels at the end of the first trimester average 6-12 ng/ml per hour, increase modestly until a few weeks before term, and then stabilize. Urine aldosterone excretion rises as well: 40-80 mcg/d in the first trimester and 100-150 mcg/d at term (2). Similar levels are observed in women with chronic hypertension; PRA remains elevated even when taking medications known to suppress renin (2).…”

“…This is supported by the low PRA and high 24-hour urine aldosterone excretion, tests that were ordered because of hypokalemia. PRA increases in normal pregnancy in the first trimester, in response to vasodilation and lower BP (2). Levels at the end of the first trimester average 6-12 ng/ml per hour, increase modestly until a few weeks before term, and then stabilize.…”

Pool walking may temporarily improve renal function by suppressing renin-angiotensin-aldosterone system in pregnant women

“…Blood samples were collected at the start and end of each walking activity, and the starting and ending levels of plasma renin activity (PRA), serum aldosterone (SA), hematocrit, and serum creatinine were measured. 18,19 Within each walking activity, we calculated the changes in each parameter, subtracting the starting levels from the ending levels. According to previous studies, we defined the change in PRA as a potential indicator for the regulation of the renin-angiotensin-aldosterone system.…”

“…According to previous studies, we defined the change in PRA as a potential indicator for the regulation of the renin-angiotensin-aldosterone system. 13,14,18,19…”

“…17 However, few studies have assessed the effect of maternal physical activities during pregnancy in water. 18,19…”