Preparation for Oral Sodium Loading Confirmatory Testing
An oral sodium loading test for primary aldosteronism should use a liberal sodium regimen with biochemical confirmation by 24-hour urine sodium collection. The test should not be performed in patients with severe uncontrolled hypertension, renal insufficiency, cardiac arrhythmia, or severe hypokalemia. [1]
Sodium Intake Prescription and Verification
- Patients should increase dietary sodium intake to >200 mmol (~6 g) per day for 3 days. [1]
- Sodium loading adequacy should be verified by 24-hour urine sodium content. [1]
Timing and Sample Integrity
- The confirmatory test protocol should incorporate standardized 24-hour urine collection for sodium and aldosterone quantification during the sodium-loading period. [1]
Medication Management During Test Period
- Blood pressure should be controlled during confirmatory testing using antihypertensive medications with minimal or no effects on the renin-angiotensin-aldosterone system. [1]
- Options with minimal effects include verapamil slow-release, hydralazine, prazosin, doxazosin, and terazosin. [1]
- Furosemide should be avoided in patients at risk of arrhythmia during confirmatory testing requiring sodium loading. [1]
Contraindications and Safety Exclusions
The oral sodium loading test should not be performed in patients with any of the following:
- Severe uncontrolled hypertension. [1]
- Renal insufficiency. [1]
- Cardiac arrhythmia. [1]
- Severe hypokalemia. [1]
Patient Selection Considerations for Interpretation
- Primary aldosteronism is unlikely when urinary aldosterone is <10 μg/24 h (28 nmol/day) in the absence of renal disease, because lower urinary aldosterone may occur when primary aldosteronism coexists with renal disease. [1]