Aldosterone

Function

Aldosterone is a steroid hormone produced by the adrenal cortex. Its primary function is to regulate the balance of sodium and potassium in the blood. By signaling the kidneys to retain sodium and excrete potassium, it indirectly controls water retention and blood pressure. It is a key component of the Renin-Angiotensin-Aldosterone System (RAAS).

Why it is Ordered

Physicians order an aldosterone test primarily to diagnose disorders of blood pressure and electrolyte balance. It is often ordered alongside a Renin test to calculate the Aldosterone-to-Renin Ratio (ARR). Common reasons include:

• Resistant Hypertension: High blood pressure that doesn't respond to standard medications.
• Hypokalemia: Unexplained low potassium levels.
• Adrenal Screening: To check for tumors or overactivity of the adrenal glands.

Associated Conditions

• Primary Hyperaldosteronism (Conn's Syndrome): Excessive production of aldosterone, usually by an adrenal tumor, leading to high blood pressure and low potassium.
• Secondary Hyperaldosteronism: High aldosterone caused by factors outside the adrenal gland, such as heart failure, liver cirrhosis, or kidney disease.
• Addison's Disease (Adrenal Insufficiency): Low production of aldosterone, leading to low blood pressure and high potassium levels.