Captopril-induced plasma aldosterone concentration (qualitative/quantitative screening)

What This Test Measures

Aldosterone is a hormone that helps regulate blood pressure and fluid balance in your body. This test checks how your body produces aldosterone after taking captopril, a medication that can temporarily lower blood pressure and affect hormone levels. The test helps doctors determine if you have a condition called primary aldosteronism, where your body makes too much aldosterone.

Why It’s Done

Your doctor may order this test if you have high blood pressure that doesn’t respond well to medications, frequent headaches, muscle weakness, or unexplained low potassium levels. It’s also used to check if you have a condition called primary hyperaldosteronism, which can cause high blood pressure and other health issues.

How It’s Done

You’ll take a pill called captopril at home, usually in the morning. Then, you’ll provide a blood sample (plasma) about 1–2 hours later. The test measures aldosterone levels in your plasma to see how your body reacts to the drug.

What to Expect Before the Test

No special preparation is needed, but you should avoid certain medications (like some blood pressure drugs) that could affect results. Follow your doctor’s instructions carefully.