Conn’s syndrome, also known as primary aldosteronism, is a disorder where the adrenal glands produce an excess amount of the hormone aldosterone. These glands, located atop the kidneys, regulate the body’s balance of sodium and potassium. When too much aldosterone is present, it causes the body to retain sodium (salt) and water, while simultaneously losing potassium. This imbalance directly contributes to elevated blood pressure, also known as hypertension.
Causes of Conn’s Syndrome
The overproduction of aldosterone in Conn’s syndrome typically stems from issues within the adrenal glands themselves. One common cause is an adrenal adenoma, a benign (non-cancerous) tumor that develops on one of the adrenal glands. This tumor autonomously produces aldosterone, leading to the hormonal imbalance. Another frequent cause is bilateral adrenal hyperplasia, which involves the enlargement and overactivity of both adrenal glands. In this condition, both glands produce an excessive amount of aldosterone. While these two causes account for most cases, rarer reasons for Conn’s syndrome, such as adrenal cancer or inherited disorders, can also occur.
Symptoms of Conn’s Syndrome
The primary symptom associated with Conn’s syndrome is high blood pressure, which can range from moderate to severe and may be resistant to standard medications. Headaches, blurred vision, and dizziness may also accompany the elevated blood pressure. Beyond hypertension, many individuals with Conn’s syndrome experience symptoms related to low potassium levels, a condition called hypokalemia. Aldosterone’s action causes the kidneys to excrete more potassium, leading to symptoms like fatigue, muscle weakness, and muscle cramps. Excessive thirst and frequent urination are also common manifestations of this electrolyte imbalance.
The Diagnostic Process
Diagnosing Conn’s syndrome involves a multi-step process to identify the hormonal imbalance and its source. The initial screening often involves a blood test to measure the aldosterone-renin ratio (ARR). This test compares the levels of aldosterone (which are typically high) to renin (which are usually low or undetectable). A high ratio serves as a primary indicator for further investigation.
If the screening suggests Conn’s syndrome, confirmatory tests are performed to verify the diagnosis. These might include a saline infusion test or an oral sodium loading test. The purpose of these tests is to determine if the body can suppress aldosterone production under specific conditions, which would not happen in someone with Conn’s syndrome.
Once confirmed, the next step is to pinpoint the exact cause, whether it’s an adenoma or bilateral hyperplasia. An abdominal CT scan is often used to look for a tumor on the adrenal glands. However, the “gold standard” for localizing the source of excess aldosterone is adrenal vein sampling (AVS). This procedure involves drawing blood directly from the veins of each adrenal gland to measure aldosterone levels, helping to determine if one gland or both are overproducing the hormone.
Treatment Approaches
Treatment for Conn’s syndrome is tailored to the specific cause identified during the diagnostic phase. For individuals with an aldosterone-producing adrenal adenoma, the primary treatment is surgical removal of the affected adrenal gland, a procedure known as laparoscopic adrenalectomy. This minimally invasive surgery often results in a cure, with a significant improvement or normalization of blood pressure and potassium levels.
In cases of bilateral adrenal hyperplasia, where both adrenal glands are overactive, surgery is generally not performed. Instead, lifelong medication is the standard treatment. Mineralocorticoid receptor antagonists, such as spironolactone or eplerenone, are commonly prescribed. These medications work by blocking the effects of aldosterone on the body, helping to regulate blood pressure and potassium levels. Additionally, lifestyle modifications, including adherence to a low-sodium diet, are recommended to support overall blood pressure management.