Determination of urinary N-acetyl-beta-glucosaminidase in patients with hypertension and renal artery stenosis.

The purpose of the study was to measure the urinary excretion of N-acetyl-beta-glucosaminidase (U-NAG) in patients suspected of having renovascular hypertension and to compare the enzyme excretion before and after active intervention with operation or percutaneous transluminal renal angioplasty (PTRA). Eighty-one patients with severe, therapy-resistant hypertension were examined with regard to renal artery stenosis (RAS). At least one significant renal artery stenosis was found in 61 patients, whilst the remaining 20 patients were classified as having essential hypertension. Enzyme levels were found to be significantly higher in RAS patients as compared with patients with severe hypertension lacking significant renal artery stenosis, 0.66 (0.41-0.91, median value, 1st and 3rd quartiles) versus 0.35 (0.27-0.54); P < 0.01. Both groups of patients had significantly higher U-NAG values than a healthy reference population (0.2, 0.13-0.27; P < 0.01). Forty of the RAS patients were randomized to surgery or PTRA and followed prospectively for 2 years. After either renal vascular surgery or PTRA a significant rise in U-NAG excretion was observed 7-10 days after treatment. Urinary NAG excretion remained elevated during long-term follow-up. It is suggested that U-NAG should be determined in patients with therapy-resistant hypertension with suspicion of renal artery stenosis.