Case 100 - Primary Aldosteronism in Pregnancy

Abstract

Primary aldosteronism (PA) is uncommon in pregnancy, with fewer than 64 cases reported in the medical literature; most of these reported patients had aldosterone-producing adenomas (APAs). PA can lead to intrauterine growth retardation, preterm delivery, intrauterine fetal demise, and placental abruption. Case-detection testing for PA in a pregnant woman is the same as for nonpregnant patients: morning blood sample for the measurement of aldosterone and renin. The combination of suppressed renin and an aldosterone level >10 ng/dL is a positive case-detection test for PA. If spontaneous hypokalemia is present in the woman with high plasma aldosterone concentration (≥20 ng/dL) and suppressed renin, confirmatory testing is not needed. In a normokalemic woman with a positive case-detection test, confirmatory testing should be pursued. However, the captopril stimulation test is contraindicated in pregnancy, and the saline infusion test may not be well tolerated. One option is measurement of sodium and aldosterone in a 24-hour urine collection on an ambient sodium diet. Subtype testing with abdominal magnetic resonance imaging (MRI) without gadolinium is the test of choice. Computed tomography (CT) and adrenal venous sampling (AVS) should be avoided in pregnancy. In patients with vigorous PA who are less than 35 years old and have a clear-cut, unilateral adrenal adenoma on MRI, AVS is not needed. The type of treatment for PA in pregnancy depends on how difficult it is to manage the hypertension and hypokalemia. If the patient is in the subset of those who have a pregnancy-related remission in the degree of PA during pregnancy, then surgery or treatment with a mineralocorticoid receptor antagonist (MRA) can be avoided until after delivery. However, if PA accelerates during pregnancy and hypertension and hypokalemia are marked, then surgical and/or targeted medical intervention with a MRA is indicated. Unilateral laparoscopic adrenalectomy during the second trimester can be considered in those women with confirmed PA and a clear-cut unilateral adrenal macroadenoma (>10 mm).