What are the diagnostic criteria for primary hyperaldosteronism (Conn's syndrome)?

From the Guidelines

The diagnostic criteria for primary hyperaldosteronism (Conn's syndrome) should begin with screening via plasma aldosterone concentration (PAC) to plasma renin activity (PRA) ratio, with a cutoff value of 30 when plasma aldosterone concentration is reported in nanograms per deciliter (ng/dL) and plasma renin activity in nanograms per milliliter per hour (ng/mL/h), as recommended by the most recent guidelines 1. The diagnosis of primary hyperaldosteronism is crucial due to its significant impact on morbidity, mortality, and quality of life, as it can lead to increased target organ damage, including left ventricular hypertrophy, diastolic dysfunction, and kidney damage 1. To accurately diagnose primary hyperaldosteronism, the following steps should be taken:

• Obtain morning blood samples with the patient in a seated position
• Discontinue interfering medications like ACE inhibitors, ARBs, and diuretics for at least 4 weeks before testing, as recommended by the guidelines 1
• Maintain normal dietary sodium intake and ensure serum potassium is in the normal range
• Use a cutoff value of 30 for the PAC/PRA ratio, with a plasma aldosterone concentration of at least 10 ng/dL to interpret the test as positive 1 If the PAC/PRA ratio is elevated, proceed to confirmatory testing, such as the saline suppression test or oral salt-loading test, to verify autonomous aldosterone secretion 1. Additional workup may include:
• CT imaging of the adrenal glands to identify potential adenomas
• Adrenal vein sampling to determine if hyperaldosteronism is unilateral or bilateral, which is essential for deciding on surgical treatment 1 The management of primary hyperaldosteronism depends on its subtype, with unilateral forms being amenable to surgical treatment and bilateral forms requiring lifelong medical treatment with mineralocorticoid receptor antagonists, such as spironolactone or eplerenone 1.

From the Research

Diagnostic Criteria for Primary Hyperaldosteronism (Conn's Syndrome)

The diagnostic criteria for primary hyperaldosteronism (Conn's syndrome) involve a sequence of tests, including:

• Screening tests: The aldosterone-to-renin ratio (ARR) is the most sensitive screening test for primary aldosteronism (PA) 2.
• Confirmatory tests: After a positive screening test, several confirmatory tests can be used, including:
  • Oral sodium loading 3
  • Saline infusion 3, 4
  • Fludrocortisone suppression 3
  • Captopril challenge 3
  • Furosemide test 2
• Subtype differentiation: After confirmation of primary hyperaldosteronism, differential diagnosis between aldosterone-producing adenoma and idiopathic hyperaldosteronism is necessary, using tests such as:
  • Adrenal CT or MRI 2, 4
  • Posture test 4
  • Adrenal vein catheterization (gold standard test) 2, 4

Key Considerations

• The Endocrine Society Guidelines recommend that patients with a positive ARR should undergo a confirmatory test to definitively confirm or exclude the diagnosis of PA 3, 5.
• Bilateral adrenal vein sampling (AVS) is the gold standard method to define the PA subtype, but it is not indicated in all cases 2.
• The choice of confirmatory test may depend on the patient's specific situation and the availability of testing procedures 3.