Aspirin test for differentiation of unilateral renovascular hypertension from hyperreninemic essential hypertension

Responses of renin release and blood pressure to aspirin DL-lysine (ASP) were examined to find out if the responses could help in the differentiation between unilateral renovascular hypertension (RVH) and hyperreninemic essential hypertension (EHT). The two studies involved ten patients with unilateral RVH, eight with hyperreninemic EHT, and five with hyporeninemic EHT. In a radiological study, before and 30 min after an intravenous injection of ASP (18 mg/kg), renal venous and abdominal aortic plasma was sampled and assayed for prostaglandin (PG) E2 and plasma renin activity (PRA). Systemic blood pressure was measured serially. The reproducibility of the responses to ASP was confirmed in a bedside study. In unilateral RVH, ASP suppressed renin release from the stenotic kidney and reduced the renal vein PRA ratio to less than 1.5 via the inhibition of PG synthesis, which is accelerated in that kidney. The mean suppression of aortic PRA at this dose of ASP was 35% in these patients, and their blood pressure decreased in proportion to the suppression of PRA. However, in the two EHT groups, ASP elevated the mean blood pressure. The renal synthesis of PGE2 was inhibited by ASP in all patients, but the suppression of PRA, while small, was significant (19% in the aorta) in the patients with hyperreninemic EHT, and not significant in patients with hyporeninemic EHT. The different responses of blood pressure and PRA to ASP between RVH and EHT were reproducible in the bedside study.(ABSTRACT TRUNCATED AT 250 WORDS)