Aldosterone

Definition

Mineralocorticoid hormone produced by the adrenal cortex, increasing renal sodium reabsorption and indirectly water reabsorption.

How it works

Aldosterone is synthesized in the glomerular zone of the adrenal cortex and released in response to angiotensin II, increased plasma potassium, or decreased sodium. It acts on principal cells of the collecting tubule by increasing expression and activity of sodium channels and Na+/K+/ATPase pumps. Increased sodium reabsorption creates an osmotic gradient that leads to secondary water reabsorption. Aldosterone maintains blood volume and pressure. Excessive aldosterone causes hypertension, while its deficiency leads to sodium and fluid loss.

Role

Regulates sodium and fluid balance and maintains blood volume and pressure.

Examples

• Increased during dehydration
• Suppressed during sodium overload
• Elevated in Conn's syndrome
• Reduced in adrenal insufficiency

Recommendations

Maintain a moderate sodium intake and adequate hydration to allow aldosterone to function correctly. Evaluate aldosterone function in case of blood pressure disorder.

Key takeaway

Aldosterone is the major hormonal regulator of sodium-fluid balance and blood pressure.

Related terms