[Isotopic renogram after captopril administration: clinical experience in the assessment of the hypertensive patient].

BACKGROUND

Isotopic renogram allows renal function to be estimated in both kidneys independently. The glomerular filtrate in ischemic kidneys is largely dependent on the tone of the efferent glomerular arteriolae and therefore on the concentration of circulating angiotensin II.

METHODS

In 42 patients with severe high blood pressure in whom renal angiographic study was carried out for suspicion of vasculo-renal hypertension, an isotopic renogram using 99m Tc-DTPA as a tracer was performed in basal conditions and following the administration of 50 mg of oral captopril.

RESULTS

In 21 patients both the angiographic examination and the post-captopril renogram were normal. In 16 patients in whom uni or bilateral stenosis higher than 50% of the lumen of renal artery was observed on angiographic examination, the post-captopril renogram showed changes. In 5 patients the angiography was normal while the renogram showed evaluable changes. No false negatives were observed in the post-captopril renogram, however the basal renogram was not demonstrative in 6 patients with stenosis of the renal artery. Sensitivity of the test was thus 100% and specificity 80%. The positive predictive value was 76% and the negative predictive value 100%.

CONCLUSIONS

The post-captopril renogram may be a useful test in the functional study of renal behaviour in patients with vasculo-renal hypertension.