Low-renin hypertension is a subtype of high blood pressure where a person has lower than typical renin levels. Renin is an enzyme that regulates blood volume and blood pressure.

While it can affect anyone, it is more prevalent in African Americans and Caribbean Hispanics. Various genetic or acquired syndromes can also cause low-renin hypertension. Diagnosing the cause is vital for treatment since low-renin hypertension may not respond well to standard high blood pressure treatments.

Renin is part of a cascade of chemical processes that ultimately influence blood pressure. The kidneys release renin, which triggers the release of angiotensin and aldosterone. The latter regulates blood pressure and salt levels in the blood. High aldosterone can increase salt sensitivity, raising blood pressure.

Low renin may be the body’s way of reacting to excess sodium.

Read on to learn more about low-renin hypertension.

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Low-renin hypertension occurs when a person has atypically lower renin levels, which leads to high blood pressure.

Renin is part of the renin-angiotensin-aldosterone system (RAAS). The kidneys secrete renin, partially in response to lower blood pressure. Primarily, renin stimulates the release of angiotensin II, which then causes aldosterone levels to rise. Together, these three chemicals elevate blood pressure and promote more absorption of salt.

However, in low-renin hypertension, aldosterone levels are often either typical or high. Measuring aldosterone levels may help diagnose the underlying cause.

Researchers do not fully understand why some people with low renin develop high blood pressure. Some research suggests that increased salt sensitivity has associations with low circulating renin levels.

Like other causes of hypertension, low-renin hypertension often does not cause symptoms. A person may feel fine, and the first sign might be a high blood pressure reading. Symptoms may also not appear for some people until hypertension causes serious problems, such as organ damage.

However, when symptoms do occur, they may include:

When a person has hyperaldosteronism — or elevations in aldosterone — they may have symptoms. Aldosterone regulates blood pressure and salt levels in the blood.

Symptoms of hyperaldosteronism include:

However, low renin does not necessarily cause elevated aldosterone.

Several inherited syndromes can cause low-renin hypertension. It can also be a symptom of a very high salt diet.

To determine the cause, doctors will consider aldosterone levels:

  • Low-normal aldosterone may signal Gordon syndrome, a rare inherited disorder that can also affect the joints.
  • Low aldosterone can signal several genetic and acquired causes, including:
  • High-normal aldosterone may signal primary hyperaldosteronism, the most common cause of low-renin hypertension. Primary hyperaldosteronism can occur for various reasons, including cancers and rare genetic syndromes.

Diagnosis begins with multiple blood pressure readings to confirm a person has high blood pressure. A person may need to check their blood pressure at home over several days or weeks.

A doctor will review a person’s medical or family history, including their medications and general lifestyle habits. Other helpful tests to assess for low-renin hypertension involve:

  • blood tests, potentially to evaluate levels of renin and aldosterone
  • urine tests
  • genetic testing, especially if doctors suspect a person has a rare genetic disease
  • aldosterone suppression tests, if doctors suspect a person has primary hyperaldosteronism

Many factors can affect the levels of renin in the blood. For example, consuming a high salt diet or taking certain medications. A doctor will consider these when evaluating results.

Treatment depends on the cause of low-renin hypertension. It can involve the following.

Medication

Doctors may prescribe drugs according to a person’s underlying diagnosis. For example, people with Liddle syndrome often respond well to amiloride or triamterene drugs.

Also, doctors may prescribe other diuretics, which are a standard treatment for most forms of high blood pressure.

Learn more about diuretics.

Surgery

Doctors may recommend surgery for hyperaldosteronism due to adrenal adenoma, which refers to a benign tumor, from one adrenal gland. When hyperaldosteronism is due to adrenal hyperplasia — or swelling — that affects both adrenal glands, medication is usually the best course of action.

Learn more about adrenal gland removal.

Doctors often recommend exercise and weight loss to control blood pressure. Little recent research has assessed its effectiveness in low-renin hypertension. However, exercise can promote heart health and may help reduce the risk of other forms of high blood pressure.

Other measures a doctor may recommend include:

  • quitting smoking, if applicable
  • maintaining or attaining a moderate body weight
  • treating obstructive sleep apnea

Because people with low-renin hypertension are often sensitive to salt, a low sodium diet can improve symptoms. Table salt is only one source of sodium in the diet, so people need to check food labels, especially for highly processed and preprepared packaged meals.

Low renin-hypertension is a subtype of high blood pressure where a person has reduced levels of renin. People with this condition may not respond well to standard high blood pressure treatments.

Only a healthcare professional can diagnose low renin and help determine its cause, so seek medical care for high blood pressure. Consult a doctor if there is a family history of low renin or metabolic syndromes, as these are risk factors for low-renin hypertension.

A doctor may recommend treatments that treat the underlying cause of low renin levels or lifestyle modifications to help someone manage their condition better, such as eating a low sodium diet.