Increased excretion of urinary N-acetyl-beta-glucosaminidase in essential hypertension and its decline with antihypertensive therapy.

The urinary excretion of N-acetyl-beta-glucosaminidase (NAG) is increased in patients whose renal function is impaired by a variety of kidney diseases, and may provide an index of renal injury. To assess its role in essential hypertension, we measured urinary levels of NAG in 80 subjects with essential hypertension (and no evidence of renal disease) and 30 normal controls. NAG values were measured before therapy and after 3 and 12 months of treatment with diuretics. The mean urinary NAG value (+/- S.D.) for the normotensive subjects was 29 +/- 16 nmol per hour per milligram of urinary creatinine. The median value for the untreated hypertensive subjects was 53, and the mean was 65 +/- 61 (P less than 0.01). Systolic blood pressure was directly correlated with NAG levels, whereas diastolic pressure, age, sex, and race were not. Eighty patients followed for one year attained their ultimate blood-pressure reduction within three months (from a mean of 158/103 mm Hg to one of 138/91 mm Hg; P less than 0.001), whereas the urinary NAG level had not declined significantly at three months (from 60 +/- 43 to 54 +/- 54) but had changed significantly at one year (to 45 +/- 28; P less than 0.01 as compared with the initial value). These data suggest that NAG is frequently elevated in patients with high blood pressure even though there is no other evidence of renal damage, and that it can be reduced by successful antihypertensive therapy.