An elevation in the aldosterone with a markedly decreased plasma renin activity is evidence for primary hyperaldosteronism.
Patient Preparation: The patient should be kept supine prior to sample collection.
aldosterone-to-renin ratio =
= (plasma aldosterone) / (plasma renin activity)
Interpretation:
• Primary aldosteronism is suspected if (1) the plasma aldosterone level is increased, (2) the plasma renin is decreased, and (3) the aldosterone-to-renin ratio is > 50.
• With exogenous or endogenous mineralocorticoids, hypervolemic hypertension and hypokalemia will be present and the plasma renin activity will be reduced, but aldosterone levels will also be depressed.
Limitations:
• False positive tests may occur, especially in patients taking beta-adrenergic blockers.
• Assays for plasma renin activity can be problematic.
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