A 52-year-old man presents to the clinic for a routine follow-up of hypertension that has been difficult to control. Despite adherence to maximum tolerated doses of amlodipine, lisinopril, and doxazosin, his blood pressure today is 162/98 mm Hg. The patient reports no headaches, palpitations, or diaphoresis. Laboratory studies show a serum potassium of 3.9 mEq/L and a serum sodium of 142 mEq/L. Suspecting a secondary cause of hypertension, the physician orders a screening panel which reveals a plasma aldosterone concentration of 22 ng/dL and a plasma renin activity of 0.5 ng/mL/hr (aldosterone-to-renin ratio = 44). Which of the following is the most appropriate next step in the diagnostic workup?
- AComputed tomography of the abdomen
- BAdrenal venous sampling
- Intravenous saline infusion testCevap
- DMeasurement of 24-hour urine free cortisol
- ERenal artery duplex ultrasonography
Cevap
The most appropriate next step is an intravenous saline infusion test to biochemically confirm autonomous aldosterone production.
The correct answer is the intravenous saline infusion test. The diagnostic algorithm for primary hyperaldosteronism strictly requires biochemical confirmation of autonomous aldosterone production before any anatomical imaging is performed. The patient's elevated aldosterone-to-renin ratio (>20) and plasma aldosterone concentration (>15 ng/dL) constitute a positive screening test. An intravenous saline infusion test or an oral sodium loading test serves as the confirmatory step by attempting to suppress aldosterone levels. Failure to suppress confirms the diagnosis, at which point localization with a CT scan would become appropriate.
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Anahtar Kavram
In the diagnostic workup of primary hyperaldosteronism, a positive screening test (aldosterone-to-renin ratio) must be followed by biochemical confirmatory testing (such as an intravenous saline infusion test) prior to ordering any anatomical imaging.