Renin secretion and captopril stimulation in hypertensive renal transplant recipients.

Basal renin secretion and the diagnostic value of a captopril stimulation (captopril test) in identifying renovascular hypertension secondary to transplant renal artery stenosis was assessed in 69 patients with hypertension after renal transplantation. An increase of plasma renin activity of 260% 1 h after captopril was considered as a positive result, assuming renovascular hypertension. Six of 69 patients had a positive captopril test, of these patients 5 had transplant renal artery stenosis. These patients were treated with percutaneous transluminal angioplasty (PTA) or surgery. Based on angiographic results and blood pressure response after PTA or surgery the captopril test showed a sensitivity of 100% and a specificity of 92% in the identification of hemodynamically significant stenosis of the transplant artery. Therefore, the captopril test provides a suitable screening instrument for the differential diagnosis of hypertension following renal transplantation.