Evaluation of renovascular hypertension.

Many tests are available for the evaluation of renovascular hypertension; each of these has its own advantages and disadvantages as a screening test. The nonimaging tests include measurement of peripheral plasma renin activity, the captopril test, and renal vein renin sampling, all of which have inherent limitations. Screening tests also are available that provide more information as anatomic or physiologic images. Among the anatomic imaging methods, intravenous urography is the least accurate screening test, although it may provide other useful information. Magnetic resonance angiography may prove to be useful, although its use is limited by its high cost. The gold standard at present for diagnosing renal artery stenosis is contrast angiography, and improvements have been made using digital subtraction technology. However, its invasive nature and high cost do not warrant its routine use as a screening test in the evaluation of renovascular hypertension. Doppler sonography is a physiologic imaging test, and although it is limited because of its operator-dependent nature, it is most useful in the evaluation of patients with renal transplants. Captopril renal scintigraphy is another physiologic imaging test, and it has proven to be an excellent initial screening test that provides both diagnostic and prognostic information.