Microalbuminuria in elderly hypertensives: reproducibility and relation to clinic and ambulatory blood pressure


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Abstract

ObjectiveTo examine the short-term reproducibility of urinary albumin measurements and the relation of urinary albumin excretion to the clinic and ambulatory blood pressure levels in elderly untreated hypertensive subjects.SettingOutpatient hypertension clinic of a District General Hospital.Main outcome measuresThe within-patient reproducibility of 24-h urinary microalbumin and electrolyte excretion and relation to 24-h and clinic blood pressure levels.PatientsSixty-four untreated elderly hypertensives (mean age 74.7 years, range 64–82) with systolic blood pressure ≥ 160 mmHg or diastolic blood pressure ≥ 95 mmHg, or both, were recruited from general practitioner clinics and current outpatient attenders. The patients had not received antihypertensive treatment for at least 4 weeks.MethodsThe clinic and 24-h non-invasive ambulatory blood pressures were recorded with a simultaneous 24-h urine collection for measurement of the urinary albumin and electrolyte excretion. Thirty-seven subjects performed two consecutive 24-h urine collections for an assessment of the short-term reproducibility of the albumin and electrolyte excretion.ResultsThe coefficient of variation of 24-h urinary albumin excretion was 62%, and for the albumin creatinine ratio 52%, compared with 19% for sodium and 15% for potassium excretion. The urinary 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 with microalbuminuria (24-h urinary albumin excretion in the range 30–300 mg) had higher clinic and ambulatory blood pressures than those with lower levels of albumin excretion.ConclusionsThe low day-to-day intrasubject reproducibility in the 24-h urinary albumin excretion considerably reduces the potential value of single collections in the assessment of microalbuminuria in elderly hypertensives. The urinary albumin excretion correlates with the clinic and 24-h ambulatory blood pressures in elderly hypertensives.

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