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The Aldosterone to Renin Ratio (ARR) is a screening test used to help identify primary aldosteronism, a condition where the adrenal glands produce too much aldosterone. It's calculated by dividing the plasma aldosterone concentration by the plasma renin activity.
The calculator uses the ARR formula:
Where:
Explanation: The ratio compares the level of aldosterone to renin in the blood, helping to identify cases where aldosterone production is inappropriately high relative to renin levels.
Details: ARR is the primary screening test for primary aldosteronism, a potentially curable cause of hypertension. An elevated ARR suggests further testing may be needed to confirm the diagnosis.
Tips: Enter aldosterone in pg/mL and renin in ng/mL/h. Both values must be greater than zero. For accurate results, patients should be off interfering medications when possible and samples should be collected in the morning after the patient has been upright for at least 2 hours.
Q1: What is a normal ARR value?
A: Normal values vary by laboratory, but typically an ARR greater than 20-30 (pg/mL per ng/mL/h) is considered elevated and may suggest primary aldosteronism.
Q2: What medications can affect ARR?
A: Many medications can affect ARR, including beta-blockers, ACE inhibitors, ARBs, diuretics, and NSAIDs. Ideally, patients should be off these medications before testing when possible.
Q3: What conditions can cause a false-positive ARR?
A: Conditions such as chronic kidney disease, pregnancy, and hypokalemia can affect the ARR. The test should be interpreted in clinical context.
Q4: What is the next step if ARR is elevated?
A: An elevated ARR typically requires confirmatory testing, such as saline infusion test, captopril challenge test, or oral sodium loading test.
Q5: Can ARR be used to monitor treatment?
A: While primarily a diagnostic tool, ARR can sometimes be used to monitor response to treatment in confirmed cases of primary aldosteronism.