Primary aldosteronism

Primary Aldosteronism

Chemical structure of aldosterone

Adrenal gland showing Conn syndrome

Primary aldosteronism, also known as Conn's syndrome, is a condition characterized by excessive production of the hormone aldosterone by the adrenal glands, leading to low renin levels. This overproduction of aldosterone causes the body to retain sodium and lose potassium, resulting in hypertension (high blood pressure) and hypokalemia (low potassium levels).

Pathophysiology

Primary aldosteronism is caused by an abnormality in the adrenal glands. The most common causes include:

• Aldosterone-producing adenoma (APA): A benign tumor in the adrenal gland that produces aldosterone.
• Bilateral adrenal hyperplasia (BAH): Enlargement of both adrenal glands leading to increased aldosterone production.
• Unilateral adrenal hyperplasia: Enlargement of one adrenal gland.
• Adrenal carcinoma: A rare cause where a malignant tumor produces aldosterone.

The excess aldosterone leads to increased reabsorption of sodium and water in the kidneys, which increases blood volume and blood pressure. It also causes increased excretion of potassium, leading to hypokalemia.

Symptoms

The symptoms of primary aldosteronism can vary but often include:

• Hypertension that is difficult to control
• Muscle weakness
• Fatigue
• Headaches
• Numbness
• Increased thirst and urination

Diagnosis

Diagnosis of primary aldosteronism involves several steps:

1. Screening tests: Measurement of plasma aldosterone concentration (PAC) and plasma renin activity (PRA) to calculate the aldosterone-to-renin ratio (ARR). 2. Confirmatory tests: Saline infusion test, oral sodium loading test, or fludrocortisone suppression test to confirm the diagnosis. 3. Imaging studies: CT scan or MRI of the adrenal glands to identify adenomas or hyperplasia. 4. Adrenal vein sampling: To differentiate between unilateral and bilateral disease.

Treatment

Treatment options for primary aldosteronism depend on the underlying cause:

• Surgical removal: Adrenalectomy is recommended for patients with an aldosterone-producing adenoma.
• Medications: Mineralocorticoid receptor antagonists such as spironolactone or eplerenone are used to treat bilateral adrenal hyperplasia or when surgery is not an option.
• Lifestyle changes: Dietary modifications, such as reducing sodium intake, can help manage symptoms.

Prognosis

With appropriate treatment, the prognosis for primary aldosteronism is generally good. Surgical removal of an adenoma can cure hypertension in many patients, while medication can effectively control blood pressure and potassium levels in others.

Also see

• Hypertension
• Adrenal gland
• Endocrinology
• Hypokalemia