Conn's syndrome

Overview

Conn’s syndrome, also known as Primary Hyperaldosteronism, is a hormonal disorder characterized by excessive production of aldosterone by the adrenal glands. Aldosterone is a hormone that helps regulate blood pressure by controlling sodium and potassium levels in the body. In Conn’s syndrome, elevated aldosterone leads to sodium retention, potassium loss, and increased blood pressure (hypertension). The condition is a potentially curable cause of secondary hypertension and is more common than previously thought, especially in individuals with resistant or early-onset high blood pressure.

Causes

Conn’s syndrome results from abnormal overproduction of aldosterone, typically due to one of the following:

• Aldosterone-producing adenoma: A benign tumor in one of the adrenal glands (most common cause)

• Bilateral adrenal hyperplasia: Enlargement of both adrenal glands causing overproduction of aldosterone

• Unilateral adrenal hyperplasia or carcinoma: Rare causes of increased aldosterone

• Familial hyperaldosteronism: A rare inherited form involving genetic mutations

Symptoms

Many people with Conn’s syndrome may have no noticeable symptoms, especially in the early stages. When symptoms do occur, they are typically related to high blood pressure and low potassium levels. Common signs and symptoms include:

• High blood pressure (hypertension): Often resistant to standard treatment

• Muscle weakness or cramps: Due to low potassium (hypokalemia)

• Frequent urination (polyuria)

• Excessive thirst (polydipsia)

• Fatigue or lethargy

• Headaches

• Tingling or numbness

• Cardiac arrhythmias: In severe hypokalemia

Diagnosis

Diagnosis of Conn’s syndrome involves screening, confirmatory tests, and imaging to determine the cause and plan treatment. Key diagnostic steps include:

• Screening tests:

  • Plasma aldosterone concentration (PAC)

  • Plasma renin activity (PRA) or direct renin concentration

  • Elevated aldosterone-to-renin ratio (ARR) suggests hyperaldosteronism

• Confirmatory testing: Such as saline infusion test, oral sodium loading test, or fludrocortisone suppression test

• Blood tests: To assess potassium levels

• Imaging studies: CT or MRI scan of the adrenal glands to detect adenomas or hyperplasia

• Adrenal venous sampling (AVS): To differentiate between unilateral (surgical) and bilateral (medical) causes

Treatment

Treatment for Conn’s syndrome depends on the underlying cause and aims to normalize aldosterone levels and control blood pressure. Options include:

• Surgical treatment:

  • Adrenalectomy: Removal of the affected adrenal gland in cases of unilateral adenoma

• Medical management:

  • Mineralocorticoid receptor antagonists: Such as spironolactone or eplerenone, especially for bilateral adrenal hyperplasia

  • Antihypertensive medications: To manage blood pressure

  • Potassium supplements: If levels remain low

  • Dietary sodium restriction: To reduce fluid retention and control blood pressure

Prognosis

With timely diagnosis and appropriate treatment, the prognosis for Conn’s syndrome is generally excellent. Surgical removal of an adrenal adenoma often leads to normalization of aldosterone levels and improved or resolved hypertension. In cases requiring medical treatment, medications can effectively control symptoms and reduce the risk of cardiovascular complications. Long-term follow-up is essential to monitor blood pressure, potassium levels, and kidney function, ensuring optimal health outcomes.