What is the role of plasma renin activity (PRA) measurement in the workup of renovascular hypertension (RVHT)?

Updated: Dec 01, 2020
  • Author: Rebecca J Schmidt, DO, FACP, FASN; Chief Editor: Vecihi Batuman, MD, FASN  more...
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Answer

The baseline plasma renin activity (PRA) is elevated in 50-80% of patients with RVHT [37]. Renin levels may be increased or decreased by all antihypertensive agents. Nonsteroidal anti-inflammatory drugs (NSAIDs) decrease plasma renin levels. Measuring the rise in the PRA 1 hour after administering 25-50 mg of captopril can increase the predictive value of the test. Patients with RAS have an exaggerated increase in PRA, perhaps due to removal of the normal suppressive effect of high angiotensin II levels on renin secretion in the stenotic kidney.

The sensitivity and specificity of studies of the captopril renin test are 75-100% and 60-95%, respectively. Limitations include the need to discontinue antihypertensive medications that can affect the PRA (eg, ACE inhibitors, beta-blockers, and diuretics), the low sensitivity, and the somewhat decreased predictive value when compared to a renogram after ACE inhibition [37].

Although elevation of peripheral or renal vein PRA has been used to diagnose unilateral renal disease and predict surgical curability, an elevated plasma renin level does not establish the cause of hypertension, and levels that are within the reference range do not rule out renovascular disease [38].


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