Sodium and mineralocorticoids in normal pregnancy

Abstract

Questions regarding the role of increased aldosterone in pregnancy, whether it is associated with a tendency to lose or to retain sodium, not only have a bearing upon routine management of pregnant women, but are also of fundamental importance to our understanding of the pathophysiology of the gestational hypertensive disorders. In attempting to resolve these issues, it would seem appropriate to review studies that might help to define the role of increased mineralocorticoids in normal pregnancy. Secretion of desoxycorticosterone (DOC) is greatly increased in the third trimester of normal pregnancy as reflected by elevated levels of plasma DOC and increased excretion of urinary free DOC as well as of the urinary metabolite, tetrahydrodesoxycortisone. Claims that prophylactic therapy with thiazide diuretics reduces the incidence of preeclampsia have not been substantiated by later studies. Because proof of benefit currently is lacking and associated risks are well documented, treatment with diuretics should be avoided in pregnancy except for heart disease. Similarly, because routine restriction of dietary sodium has not been shown to prevent preeclampsia and may produce complications of sodium depletion, pregnant women should be advised to salt their food according to taste. If the physician feels compelled to treat asymptomatic edema, bed rest with the patient positioned in lateral recumbency usually promotes adequate diuresis, and if preclampsia is suspected, bed rest in the hospital with careful observation is preferable to diuretic therapy.