Aldosterone and Renin Test: What the Ratio Means

What Is the Aldosterone Renin Ratio?

The aldosterone renin ratio compares two hormones that work together to control blood pressure, sodium, and potassium. Aldosterone is made by the adrenal glands and tells the kidneys to hold on to sodium and release potassium. Renin is an enzyme released by the kidneys when blood pressure or sodium falls, and it normally triggers aldosterone production.

The renin-angiotensin-aldosterone system is one of the body's main blood-pressure controls. When the kidneys sense low pressure or low sodium, they release renin, which sets off a chain that ends with aldosterone. Measuring both hormones shows whether that chain is behaving normally, and looking at them as a ratio helps separate primary aldosteronism from secondary causes.

Why the Aldosterone Renin Test Is Ordered

An aldosterone test and a renin test are usually ordered together when high blood pressure is hard to control, or when a clinician suspects a hormone cause. Common reasons include:

• Resistant high blood pressure that needs several medicines
• High blood pressure with low potassium
• An adrenal nodule found on imaging
• High blood pressure in a young adult or with a family history of early hypertension
• Unexplained muscle weakness, cramping, or fatigue with high blood pressure

Doctors may also order the ratio when blood pressure stays high despite three or more medicines, or when potassium is low without an obvious cause. Primary aldosteronism is one of the more common secondary causes of hypertension, and because it can be treated, finding it can change how blood pressure is managed.

Normal Aldosterone and Renin Ranges

Reference ranges depend on posture, sodium intake, and the laboratory. Typical values are:

The ratio is calculated by dividing aldosterone by renin, but the exact cutoff depends on the units and the laboratory. Sodium intake matters too, because a high-salt diet can suppress renin and make the ratio look higher than it really is. Some clinicians ask for a period of normal salt intake before testing, and may correct low potassium first, since low potassium can blunt aldosterone.

A ratio above roughly 30, together with aldosterone above about 20 ng/dL, can suggest primary aldosteronism. Because of these variables, a ratio is treated as a screening result, and a positive screen is usually followed by a confirmatory test before any conclusion is drawn.

Aldosterone is measured in nanograms per deciliter (ng/dL) and renin as plasma renin activity. Some laboratories measure renin concentration instead, reported in milli-international units per liter, which changes the numeric ratio. Always check which method your report used.

What High Aldosterone Means

High aldosterone with a low renin is the classic pattern of primary aldosteronism, also called Conn syndrome. In that condition the adrenal glands make too much aldosterone even though renin is suppressed, which pushes blood pressure up and can lower potassium.

Primary aldosteronism can come from a single adrenal nodule or from both adrenal glands working overtime. The distinction matters because the two forms can be managed differently, which is why imaging and confirmatory testing often follow a high ratio. When both aldosterone and renin are high, the cause is usually secondary, such as narrowing of a kidney artery, heart failure, or liver disease.

What Low Aldosterone Means

A low aldosterone level can occur with adrenal insufficiency, where the adrenal glands make too little of several hormones. A high renin with low aldosterone can also appear when the body is dehydrated or losing sodium.

In adrenal insufficiency, aldosterone is low because the adrenal glands cannot make it, and renin may rise in response. This pattern is different from primary aldosteronism and points in the opposite direction. Because renin responds quickly to fluid and sodium changes, the test is usually done under standardized conditions, often after sitting or standing for a set time.

How to Order the Test

You can order an aldosterone and renin test directly through a direct-access lab service, with no physician's order or insurance required. Order online, pay the listed price, and visit a local collection site. A CLIA-certified laboratory processes the sample, and results are usually ready within a few business days.

Preparation usually includes avoiding very high or very low salt intake for a few days and discussing medicines with a clinician, since some blood-pressure drugs affect renin and aldosterone. The collection site may ask you to sit or stand for a set period before the draw. Some panels pair aldosterone and renin with a comprehensive metabolic panel to check potassium and kidney function at the same time.

How Much Does It Cost?

Direct-access aldosterone and renin testing typically costs between about $100 and $200, depending on the laboratory and whether the two hormones are bundled. Prices are shown before you order, and insurance is not required.

Some panels include both hormones in a single order, which is usually cheaper than ordering each one separately.