What is the initial workup for a patient suspected of having Conn syndrome (Primary Aldosteronism)?

From the Guidelines

The initial workup for a patient suspected of having Conn syndrome (primary aldosteronism) should begin with measuring the aldosterone-to-renin ratio (ARR) after ensuring the patient has adequate potassium levels and has discontinued interfering medications for at least 2-4 weeks, as recommended by the most recent guidelines 1.

Initial Screening

The ARR test is the most accurate and reliable means of screening for primary aldosteronism, with an elevated ARR (typically >20-30 ng/dL per ng/mL/hr) suggesting the condition 1.

• Blood samples should be collected in the morning with the patient in a seated position.
• The patient should have unrestricted salt intake and normal serum potassium levels before testing.
• Interfering medications such as spironolactone, eplerenone, amiloride, triamterene, potassium-wasting diuretics, and certain antihypertensives should be discontinued for at least 2-4 weeks before testing.

Confirmation Testing

Following a positive screening test, confirmation testing is necessary, which may include:

• Oral sodium loading
• Saline infusion test
• Captopril challenge
• Fludrocortisone suppression test These tests help confirm the diagnosis of primary aldosteronism and distinguish it from other causes of hypertension.

Additional Diagnostic Tests

Basic laboratory tests should include:

• Serum electrolytes (looking for hypokalemia, though 30-50% of patients may have normal potassium)
• Blood glucose
• Kidney function tests A 24-hour urine collection for aldosterone, sodium, and potassium can provide additional diagnostic information.

Importance of Accurate Diagnosis

Primary aldosteronism is a potentially curable cause of hypertension characterized by autonomous aldosterone production, typically from an adrenal adenoma or bilateral adrenal hyperplasia, leading to sodium retention, potassium excretion, and hypertension that doesn't respond well to conventional treatments 1. Accurate diagnosis and treatment can significantly improve patient outcomes, reducing the risk of cardiovascular complications and improving quality of life.

From the Research

Initial Workup for Conn Syndrome

The initial workup for a patient suspected of having Conn syndrome (Primary Aldosteronism) includes:

• Screening for primary aldosteronism by measuring the aldosterone-renin ratio in the morning 2
• Confirmatory tests to validate the diagnosis of primary aldosteronism, such as saline suppression test 3
• Adrenal imaging using CT or MRI to investigate PHA subtype 2
• Adrenal venous sampling to definitively confirm uni- or bilateral aldosterone hypersecretion 2

Patient Selection for Workup

Primary aldosteronism should be suspected in:

• Young patients with moderate to severe hypertension 4
• Patients with hypertension and coexisting hypokalemia 4
• Any patient with hypertension and an incidental adrenal adenoma 4
• Hypertension in the setting of a significant family history of early onset hypertension or cerebral vascular accident in a first degree relative less than 40 years of age 4

Diagnostic Criteria

Diagnostic criteria for primary aldosteronism include:

• Elevated plasma aldosterone level with low renin activity 5, 3
• Hypokalemia, which can be severe in some cases 5, 3
• Arterial hypertension 4, 6

Treatment and Management

Treatment and management of primary aldosteronism include:

• Endoscopical unilateral adrenalectomy for aldosterone-producing adenoma (Conn's syndrome) 2
• Mineralocorticoid receptor antagonist (e.g. spironolactone) for bilateral hyperplasia 2
• Vigorous potassium supplementation for severe hypokalemia 3
• Laparoscopic adrenalectomy for adrenal tumors 5