Aspirin renography in diagnosis of unilateral renovascular hypertension.

We previously proposed that aspirin can enhance the diagnostic sensitivity of renography with [123I] orthoiodohippurate (OIH) in patients with suspected unilateral renovascular hypertension (RVH). In this study we assessed the sensitivity and specificity of this method. Twenty-four patients, 14 with unilateral RVH and 10 with essential hypertension, were studied. For all patients with RVH, definitive diagnosis was based on the results of angiography and the response to renal arterial angioplasty after this study. For all patients with essential hypertension, we confirmed that there was little if any stenosis of the renal artery by digital subtraction angiography or Doppler sonography. Renography with [123I]OIH or 99mTc-mercaptoacetyltriglycine (MAG3) was done once before and once after the oral administration of aspirin (20 mg/kg). We considered renal blood flow to be decreased if the time to the peak in renography was 5 min or more, and defined the peak times of the kidneys as different if separated by 2 min or more. Unilateral RVH was diagnosed when both criteria were met. Renography before aspirin administration indicated RVH in 7 of the 14 patients with RVH, and renography after aspirin indicated RVH in 13 of the 14 patients. Of the 10 patients with essential hypertension, renography before and after aspirin administration showed no difference between the kidneys in 8 patients. Thus, aspirin renography increased the sensitivity from 50% to 93%, but did not change the specificity (80%) in the diagnosis of RVH. These results suggest that renography with [123I]OIH or 99mTc-MAG3 for the diagnosis of unilateral RVH is more sensitive when aspirin is used.