Aldosterone

Latest Edit: Hector 2014-03-21 (EDT)

See Also	Lab Tests

This test is used to diagnose hyperaldosteronism. A plasma renin assay may be conducted simultaneously, in order to differentiate primary aldosteronism (adrenal pathology) from secondary aldosteronism (extra-adrenal pathology).

Discussion

• Aldosterone is a hormone produced by the adrenal cortex and its production is regulated by the renin-angiotensin system.
• Aldosterone is also stimulated by ACTH, low serum sodium levels, and high serum potassium levels.
• In turn, aldosterone stimulates the renal tubules of the kidney to absorb sodium and to secrete potassium in the urine, thereby regulating serum sodium and potassium levels.
• Aldosterone also partially regulates water absorption, since water follows sodium transport.

Patient Preparation

• No fasting required.

• Factors which can cause increased levels

• Strenuous exercise, stress
• Drugs: diazoxide (Hyperstat), hydralazine (Apresoline), nitroprusside (Nipride), diuretics, laxatives, potassium, and spironolactone.

• Factors which can cause decreased levels

• Excessive licorice ingestion
• Drugs: fludrocortisone (Florinef), propranolol (Inderal), and angiotensin-converting enzyme inhibitors (e.g. captopril), and licorice

Clinical Implications

High levels indicate:

Primary Aldosteronism:

• Aldosterone-producing adrenal adenoma (Conn disease)
• Adrenal cortical nodular hyperplasia
• Bartter's syndrome

Secondary Aldosteronism:

• Hyponatremia
• Hyperkalemia
• Diuretic ingestion resulting in hypovolemia and hyponatremia
• Laxative abuse
• Stress
• Malignant hypertension
• Poor perfusion states (e.g. congestive heart failure)
• Decreased intravascular volume (e.g. cirrhosis, nephrotic syndrome)
• Renal arterial stenosis
• Pregnancy and oral contraception
• Hypovolemia or hemorrhage
• Cushing's disease

Low levels indicate:

• Aldosterone deficiency
• Renin deficiency
• Steroid therapy
• Addison's disease
• Patients on high-sodium diet
• Hypernatremia
• Toxemia of pregnancy
• Antihypertensive therapy

Associated Tests

• Serum Sodium, Sodium Urine Test, Serum Potassium, Potassium Urine Test, Adrenocorticotrophic Hormone (ACTH), Renin Assay