Correlation of Office and Ambulatory Blood Pressure Measurements with Urinary Albumin and N-Acetyl-βD-Glucosaminidase Excretions in Essential Hypertension

Ambulatory blood pressure (ABP) correlates better than office blood pressure with hypertensive changes in the heart and vasculature. Using the 24-hour urinary excretions of albumin and N-acetyl-β-D-glucosaminidase (NAG) as markers, we examined the relationship between office and ABP and target-organ changes in the kidney in 42 untreated patients with essential hypertension. Mean urinary albumin excretion was 23.2 ± 34.3 mg/day and mean urinary NAG excretion was 45.1 ± 22.9 nmol/hr/mg creatinine. Urinary albumin excretion was positively correlated with both office and mean 24-hour systolic blood pressure (r = 0.31, P < 0.05; and r = 0.44, P < 0.01, respectively). Urinary NAG excretion was positively correlated with 24-hour ambulatory systolic, diastolic, and mean blood pressure (r = 0.32, P < 0.05; r = 0.32, P < 0.05; and r = 0.39, P < 0.05, respectively), but not with office blood pressure. Thus, urinary albumin and NAG excretions are positively correlated with blood pressure and may be useful markers of renal involvement in patients with essential hypertension. Additionally, ABP may be more reliable than office blood pressure in identifying those patients at risk for hypertensive targetorgan changes in the kidney. Am J Hypertens 1988;1:117S–120S