Hyperaldosteronism for NP
Hyperaldosteronism for the Nurse Practitioner Exam
- Pathophysiology
- Excess Aldosterone: Hyperaldosteronism is due to the overproduction of aldosterone, a mineralocorticoid hormone that increases sodium reabsorption and potassium excretion in the kidneys. This causes hypertension and hypokalemia.
- Primary vs. Secondary:
- Primary Hyperaldosteronism: Excessive aldosterone production independent of renin activity. Commonly caused by an aldosterone-producing adrenal adenoma (Conn’s syndrome) or bilateral adrenal hyperplasia.
- Secondary Hyperaldosteronism: Increased aldosterone production due to activation of the renin-angiotensin-aldosterone system (RAAS), often from renal artery stenosis, heart failure, or cirrhosis.
- Etiology
- Primary Hyperaldosteronism:
- Aldosterone-Producing Adenoma (APA): The most common cause, typically involving a unilateral adrenal adenoma.
- Bilateral Adrenal Hyperplasia: A less common cause, with diffuse or nodular hyperplasia of both adrenal glands.
- Secondary Hyperaldosteronism:
- Renal Artery Stenosis: Causes decreased renal perfusion, activating the RAAS.
- Heart Failure: Perceived low blood volume stimulates renin release and increases aldosterone secretion.
- Clinical Features
- Hypertension: Often resistant to standard antihypertensive treatment.
- Hypokalemia: Causes muscle weakness, fatigue, cramps, and in severe cases, arrhythmias.
- Polyuria and Polydipsia: Due to impaired renal concentrating ability from hypokalemia.
- Metabolic Alkalosis: Resulting from increased hydrogen ion excretion.
- Diagnosis
- Aldosterone-to-Renin Ratio (ARR): A high ARR with elevated aldosterone and low renin suggests primary hyperaldosteronism.
- Confirmatory Testing: Oral sodium loading or saline infusion tests confirm the diagnosis if aldosterone levels remain elevated.
- Imaging: Adrenal CT or adrenal venous sampling to differentiate between unilateral and bilateral disease.
- Treatment
- Aldosterone-Producing Adenoma: Treated with laparoscopic adrenalectomy for unilateral disease.
- Bilateral Adrenal Hyperplasia: Managed with mineralocorticoid receptor antagonists like spironolactone or eplerenone.
- Secondary Hyperaldosteronism: Treated by addressing the underlying cause (e.g., stenting for renal artery stenosis).
Key Points
- Pathophysiology: Hyperaldosteronism involves excessive aldosterone, leading to hypertension, sodium retention, and potassium excretion.
- Etiology: Primary causes include aldosterone-producing adenomas and adrenal hyperplasia, while secondary causes involve renal artery stenosis or heart failure.
- Clinical Features: Resistant hypertension, hypokalemia, muscle weakness, polyuria, and metabolic alkalosis.
- Diagnosis: High aldosterone-to-renin ratio (ARR), confirmatory testing, and adrenal imaging.
- Treatment: Adrenalectomy for unilateral disease and medical therapy with spironolactone or eplerenone for bilateral disease.