A 56-year-old man is evaluated in the clinic for persistent hypertension. He has a 4-year history of elevated blood pressure that remains poorly controlled despite adherence to maximum tolerated doses of amlodipine, lisinopril, and hydrochlorothiazide. His blood pressure today is 162/98 mm Hg. Laboratory studies show a serum potassium level of 3.2 mEq/L and a serum sodium level of 145 mEq/L. The physician suspects primary aldosteronism.
Arrange the following diagnostic interventions in the most appropriate chronological order to establish the diagnosis, localize the pathology, and guide surgical management, assuming each successive test yields abnormal findings that necessitate further workup.
- 1Measurement of morning plasma aldosterone concentration and plasma renin activity
- 2Intravenous saline infusion test
- 3High-resolution computed tomography (CT) of the adrenal glands
- 4Bilateral adrenal vein sampling
Answer
The correct diagnostic sequence is: 1) Measurement of plasma aldosterone and renin (screening), 2) Intravenous saline infusion test (confirmation), 3) CT of the adrenal glands (initial localization), and 4) Bilateral adrenal vein sampling (definitive lateralization prior to surgery).
The correct sequence strictly adheres to current endocrine guidelines to prevent unnecessary procedures. Screening (aldosterone/renin) casts a wide net. Confirmation (saline load) ensures the disease is genuinely present. Imaging (CT) provides a structural map. Sampling (adrenal vein) provides the functional definitive proof required before removing an adrenal gland.
Step-by-Step Solution
Key Concept
The diagnostic workup for primary aldosteronism proceeds sequentially through biochemical screening, biochemical confirmation, non-invasive anatomical localization, and finally invasive functional lateralization.