MICROALBUMINURIA IN ELDERLY HYPERTENSIVES - REPRODUCIBILITY AND RELATION TO CLINIC AND AMBULATORY BLOOD-PRESSURE

Objective: To examine the short-term reproducibility of urinary albumi n measurements and the relation of urinary albumin excretion to the cl inic and ambulatory blood pressure levels in elderly untreated hyperte nsive subjects. Setting: Outpatient hypertension clinic of a District General Hospital. Main outcome measures: The within-patient reproducib ility of 24-h urinary microalbumin and electrolyte excretion and relat ion to 24-h and clinic blood pressure levels. Patients: Sixty-four unt reated elderly hypertensives (mean age 74.7 years, range 64-82) with s ystolic blood pressure greater than or equal to 160 mmHg or diastolic blood pressure greater than or equal to 95 mmHg, or both, were recruit ed from general practitioner clinics and current outpatient attenders. The patients had not received antihypertensive treatment for at least 4 weeks. Methods: The clinic and 24-h non-invasive ambulatory blood p ressures were recorded with a simultaneous 24-h urine collection for m easurement of the urinary albumin and electrolyte excretion. Thirty-se ven subjects performed two consecutive 24-h urine collections for an a ssessment of the short-term reproducibility of the albumin and electro lyte excretion. Results: The coefficient of variation of 24-h urinary albumin excretion was 62%, and for the albumin:creatinine ratio 52%, c ompared with 19% for sodium and 15% for potassium excretion. The urina ry albumin excretion correlated with clinic systolic blood pressure (r = 0.33, P = 0.01) and with 24-h ambulatory systolic (r = 0.48, P < 0. 001) and diastolic (r = 0.32, P = 0.01) blood pressure. The subjects w ith microalbuminuria (24-h urinary albumin excretion in the range 30-3 00mg) had higher clinic and ambulatory blood pressures than those with lower levels of albumin excretion. Conclusions: The low day-to-day in trasubject reproducibility in the 24-h urinary albumin excretion consi derably reduces the potential value of single collections in the asses sment of microalbuminuria in elderly hypertensives. The urinary albumi n excretion correlates with the clinic and 24-h ambulatory blood press ures in elderly hypertensives.