Saralasin test as a diagnostic and prognostic aid in renovascular hypertensive patients subjected to renal operation.

A positive saralasin test in patients with angiographic evidence of renovascular disease and other positive functional tests gives further assurance that these patients will achieve normal or substantially reduced blood pressure postoperatively. In our experience with proved renovascular hypertension there was a 19% incidence of falsely negative saralasin tests. Therefore, saralasin should not be used as the sole screening test in hypertensive patients suspected of having surgically correctable lesions. There is a direct correlation between elevated renin activity and a positive saralasin test. In some patients saralasin may be more sensitive than any other currently used test to detect overactivity of the renin-angiotensin system. This would determine those patients with technical errors in renin sampling and assays. Of the 16 patients (all normotensive) who had 6-month followup tests 5 had elevated peripheral renin activity, probably owing to furosemide stimulation. Of these 5 patients 2 had a positive postoperative saralasin test, raising the question of potential falsely positive responses in cases of essential hypertension and coincidental non-functional renal artery stenosis. Patients with high renin essential hypertension may respond to saralasin, even in the absence of renal artery lesions. A saralasin test should be done in a hospital where all specific conditions can be met and potential complications handled promptly.