From the Guidelines
The aldosterone to renin ratio (ARR) is a critical screening tool for primary aldosteronism, with a ratio greater than 30 ng/dL per ng/mL/hr indicating a positive result that warrants further investigation. This interpretation is based on the most recent and highest quality evidence from the 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline for the prevention, detection, evaluation, and management of high blood pressure in adults 1.
Key Considerations for Interpretation
- The plasma aldosterone concentration should be at least 10 ng/dL to interpret the test as positive, as very low renin levels can influence the ratio 1.
- Patients should have unrestricted salt intake, serum potassium in the normal range, and mineralocorticoid receptor antagonists (e.g., spironolactone or eplerenone) withdrawn for at least 4 weeks before testing 1.
- Blood samples should be collected in the morning after the patient has been upright for at least 2 hours and seated for 5-15 minutes.
- A positive screening result is not diagnostic on its own and requires confirmation with suppression testing such as saline infusion, captopril challenge, or fludrocortisone suppression tests to definitively diagnose primary aldosteronism 1.
Clinical Implications
- Primary aldosteronism is a common cause of secondary hypertension, occurring in 5% to 10% of patients with hypertension and 20% of patients with resistant hypertension 1.
- The diagnosis of primary aldosteronism generally requires a confirmatory test (intravenous saline suppression test or oral salt-loading test) 1.
- Treatment options for primary aldosteronism include unilateral laparoscopic adrenalectomy, which improves blood pressure in virtually 100% of patients and results in a complete cure of hypertension in about 50%, or medical therapy with spironolactone or eplerenone as the agent of choice 1.
Limitations and Future Directions
- The aldosterone to renin ratio can be influenced by various factors, including medications, laboratory-specific reference ranges, and patient demographics 1.
- Further research is needed to optimize the diagnosis and treatment of primary aldosteronism, particularly in patients with resistant hypertension or other comorbidities 1.
From the Research
Interpretation of the Aldosterone to Renin Ratio
The aldosterone to renin ratio (ARR) is a diagnostic tool used to detect primary aldosteronism, a condition characterized by excessive production of aldosterone [(2,3,4,5,6)].
Diagnostic Value of ARR
- The ARR has been shown to be a reliable screening test for primary aldosteronism, with a high sensitivity and specificity [(2,3,6)].
- A high ARR value is indicative of primary aldosteronism, while a low ARR value makes the diagnosis less likely [(2,3)].
- The cutoff value for ARR varies depending on the study, but a value of 28.3 has been suggested as a diagnostic threshold 3.
Variability of ARR
- The ARR has been shown to be variable, both in the short-term and long-term, and its reliability decreases as its value increases 4.
- Age has been found to be weakly correlated with ARR, but the cutoff values for different age groups are not more efficient than the overall cutoff value 3.
Factors Affecting ARR
- Mineralocorticoid receptor antagonists have been shown to affect the ARR, leading to a significant reduction in its value and potentially resulting in false-negative test results 5.
- The ARR is not affected by subtle glucocorticoid hypersecretion in patients with adrenal incidentalomas 6.
Clinical Implications
- The ARR should be interpreted with caution, taking into account its variability and potential factors that may affect its value [(4,5)].
- A high ARR value should be confirmed with further diagnostic tests to exclude false-positive results [(2,3)].