1. What is the Aldosterone-Renin Ratio (ARR)?

The Aldosterone-Renin Ratio (ARR) is a screening test used to identify primary aldosteronism, a condition characterized by excessive aldosterone production independent of the renin-angiotensin system. It helps differentiate primary from secondary causes of hyperaldosteronism.

2. How Does the Calculator Work?

The calculator uses the ARR formula:

Where:

• \( Aldosterone \) — Plasma aldosterone concentration in pg/mL
• \( Renin \) — Plasma renin activity in ng/mL/h

Explanation: The ratio compares the level of aldosterone to renin activity, with elevated ratios suggesting autonomous aldosterone production.

3. Importance of ARR Calculation

Details: ARR is the primary screening test for primary aldosteronism, which is a common and potentially curable cause of hypertension. Early detection can lead to targeted treatment and improved outcomes.

4. Using the Calculator

Tips: Enter aldosterone in pg/mL and renin in ng/mL/h. Both values must be greater than zero. Morning samples after overnight fasting are preferred for accurate results.

5. Frequently Asked Questions (FAQ)

Q1: What is a normal ARR value?
A: Normal ARR values typically range from 3.7-27.0 (pg/mL)/(ng/mL/h), but cutoff values may vary between laboratories and populations.

Q2: When should ARR testing be performed?
A: ARR testing should be considered in patients with resistant hypertension, spontaneous hypokalemia, or adrenal incidentaloma with hypertension.

Q3: What medications affect ARR?
A: Many antihypertensive medications can affect ARR. Beta-blockers, central alpha-2 agonists, and NSAIDs may suppress renin and increase ARR, while diuretics, ACE inhibitors, and ARBs may decrease ARR.

Q4: How should patients prepare for ARR testing?
A: Patients should be on a liberal salt diet, correct hypokalemia, and ideally have antihypertensive medications adjusted or discontinued under medical supervision before testing.

Q5: What are the limitations of ARR testing?
A: ARR has variable sensitivity and specificity. False positives can occur with renal impairment, pregnancy, or certain medications. Confirmatory testing is usually required for diagnosis.