Renin Aldosterone Ratio MDCalc

Renin Aldosterone Ratio

ARR Equation:

\[ ARR = \frac{Aldosterone\ (pg/mL)}{Renin\ (ng/mL/h)} \]

ARR (Ratio):

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

The Renin Aldosterone Ratio (ARR) is a screening test used to evaluate for primary aldosteronism, a condition characterized by excessive aldosterone production independent of the renin-angiotensin system.

2. How Does the Calculator Work?

The calculator uses the ARR equation:

\[ ARR = \frac{Aldosterone\ (pg/mL)}{Renin\ (ng/mL/h)} \]

Where:

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

Explanation: The ratio compares aldosterone levels 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.

4. Using the Calculator

Tips: Enter aldosterone in pg/mL and renin in ng/mL/h. Both values must be positive numbers. Morning samples after overnight supine position are preferred.

5. Frequently Asked Questions (FAQ)

Q1: What is a normal ARR value?
A: Typically <20-30 (pg/mL)/(ng/mL/h), but cutoff values may vary between laboratories and patient populations.

Q2: What medications affect ARR?
A: Beta-blockers, ACE inhibitors, ARBs, diuretics, and other antihypertensives can affect results. Consult with physician about medication adjustments before testing.

Q3: When is ARR testing indicated?
A: For patients with resistant hypertension, hypokalemia, adrenal incidentaloma, or early-onset hypertension.

Q4: What are the limitations of ARR?
A: Results can be affected by medications, sodium intake, time of day, and posture during blood sampling.

Q5: What follow-up is needed for elevated ARR?
A: Confirmatory testing such as saline infusion test or captopril challenge test is typically required to confirm primary aldosteronism diagnosis.