Endocrine Abstracts

Background: Screening for primary aldosteronism (PA) needs aldosterone-to-renin ratio (ARR) measurement, followed by confirmative tests.

Aim: To assess the clinical value of captopril challenge test (CCT) in PA diagnosis.

Methods: Thirty patients were screened for secondary endocrine hypertension; study group consisted in 15 PA patients (7M/8F, aged 44.6±13.3 years). Control group consisted in 15 patients (5M/10F) with negative screening for endocrine hypertension, matched for age (44.3±13.2 years) and systolic blood pressure with PA group. Plasma aldosterone and direct renin were measured by chemiluminescence. In patients with increased ARR (3.8 ng/dl/ng/l), saline infusion test (SIT) and CCT were used as confirmative tests.

Results: Serum kalemia was significantly lower in PA patients (3.6±0.7 mmol/l), than in controls (4±0.6 mmol/l), P=0.05. In PA group, serum kalemia was significantly lower in patients who underwent CCT (3.2±0.6 mmol/l) than in patients who underwent SIT (3.9±0.5 mmol/l), P=0.021. AAR was greater in PA patients who underwent CCT (80.3±53.6) than in patients who underwent SIT (8.2±5.2), P=0.007. Median decrease in aldosterone levels during CCT tended to be lower (15.45%) in PA patients than in controls (41.9%), P=0.2. Median 4 h aldosterone levels after SIT were significantly higher (80.1 pg/ml, 25th percentile: 66.6 pg/ml, 75th percentile: 125 pg/ml) in PA patients than in controls (42.4 pg/ml, 25th percentile: 34.7 pg/ml, 75th percentile: 50.61 pg/ml), P=0.02.

Conclusion: In high-risk patients with severe hypertension and hypokalemia, CCT is a useful tool in the diagnosis of PA.