Conn Syndrome

What Is It, Causes, Symptoms, Diagnosis, Treatment, and More

Author: Georgina Tiarks

Editors: Ahaana Singh, Lisa Miklush, PhD, RN, CNS

Illustrator: Jillian Dunbar

What is Conn syndrome?

Conn syndrome, also known as primary hyperaldosteronism, refers to the excessive secretion of the hormone aldosterone. Aldosterone, secreted by the adrenal glands, plays an important role in the management of blood pressure by regulating sodium and potassium levels in the kidney. By stimulating sodium reabsorption back into the blood and potassium excretion into the urine, aldosterone also causes water to be reabsorbed into the blood vessels. The influx of water into the circulation can lead to high blood pressure. Additionally, low potassium levels can cause muscle cramps and an irregular heartbeat. Typically, aldosterone production is regulated by a protein called renin, however, with Conn syndrome, aldosterone levels are elevated despite normal renin levels. 

Is Conn syndrome serious?

Conn syndrome can be considered serious due to the long-term impact of uncontrolled high blood pressure (i.e., hypertension). Without treatment, hypertension can cause an increased risk of developing heart failure, heart attacks, kidney failure, and strokes. Additionally, the associated low potassium levels (i.e., hypokalemia), can lead to an irregular heart rhythm. 

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What causes Conn syndrome?

Conn syndrome is most often caused by an adrenal tumor, such as aldosterone-producing adenomas. Commonly, these tumors are benign but in rare cases, they can be malignant. 

Less frequently, Conn syndrome can occur because of an inherited disorder called bilateral adrenal hyperplasia, which affects hormone production in the adrenal glands

Is Conn syndrome hereditary?

Conn syndrome itself is not hereditary, but may be the result of an underlying hereditary condition, such as bilateral adrenal hyperplasia.

Oftentimes, providers may want to perform genetic testing in individuals who develop hyperaldosteronism before 20 years of age or in individuals younger than 40 years of age with a family history of stroke or hyperaldosteronism. 

What are the signs and symptoms of Conn syndrome?

Most often, Conn syndrome causes high blood pressure that cannot be controlled with blood pressure medications. 

Other signs and symptoms include excessive thirst, increased urinary frequency, and nocturia, or the need to urinate during the night. In addition, individuals may also experience muscle cramps, weakness or tingling, dizziness, blurred vision, and headaches

How is Conn syndrome diagnosed?

Diagnosis of Conn syndrome usually begins with a full medical history and physical examination. Healthcare providers will likely then perform blood tests to assess one’s hormone and electrolyte levels. Specifically, examining aldosterone, renin, sodium, and potassium levels can be useful when diagnosing Conn syndrome. Some providers may also want to perform adrenal vein sampling in which blood is taken from the adrenal veins using a catheter to compare the hormone levels coming from each individual adrenal gland. Imaging, such as computerized tomography (CT) scans, may also be performed to visualize any tumors or malformations. 

In some cases, a suppression test may be used to determine whether or not the body is overproducing aldosterone. There are many types of suppression tests, such as saline or a captopril suppression test. For the saline suppression test, an individual will be given an IV salt solution and their aldosterone level will be examined. Similarly, with the captopril suppression test, also called the captopril challenge test, an individual is administered captopril, a medication used to treat high blood pressure, and consequent aldosterone levels are examined. 

How is Conn syndrome treated?

Treatment of Conn syndrome largely depends on the underlying cause. Often aldosterone-producing adenomas and other adrenal tumors may be surgically removed laparoscopically, through a minimally invasive procedure. On the other hand, bilateral adrenal hyperplasia can be treated with medications that inhibit aldosterone, such as spironolactone. In most cases, individuals are also recommended to maintain a low-salt diet, stop smoking, limit alcohol intake, and exercise regularly. 

What are the most important facts to know about Conn syndrome?

Conn syndrome, also called primary hyperaldosteronism, is characterized by an overproduction of aldosterone. Aldosterone is a hormone released by the adrenal glands that regulates blood pressure through the management of sodium and potassium levels. If untreated, it can become a serious problem as uncontrolled blood pressure can increase the risk of developing many additional health concerns. Conn syndrome is often caused by either an adrenal tumor (adenoma) or bilateral adrenal hyperplasia. In most cases, individuals will experience hypertension that cannot be controlled with blood pressure medication. They may also have blurred vision, headaches, increased urination, or muscle cramps. Blood tests, imaging scans, and suppression tests can be used to diagnose Conn syndrome. Depending on the underlying cause, Conn syndrome may be treated by either removing an aldosterone-producing tumor or taking medication to control the aldosterone levels. 

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Resources for research and reference

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Hall JE, Granger JP, Jones DW, Hall ME. Hurst’s The Heart. 14th ed. New York: McGraw-Hill Education; 2017.

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