Pattern of occurrence of microalbuminuria among dippers and non-dippers (essential hypertensives) in a Nigerian university teaching hospital

Abstract

Objectives: Hypertensives who fail to manifest the normal circadian nocturnal fall in blood pressure have a higher incidence of cardiovascular complications, early glomerular injury and microalbuminuria. This study aims to quantify the proportion of dippers and non-dippers among the essential hypertensive population, and determine the frequency of occurrence of micro-albuminuria among them.

Materials and methods: Early morning urine specimens were taken from 50 patients with essential hypertension and 20 healthy, normotensive subjects. Combined negative results from albustic strip testing and sulfosalicylic acid tests were taken as excluding microalbuminuria. While collecting urine for 24-hour urinary protein and creatinine clearance, hourly blood pressure readings were recorded. Readings obtained between 07:00 and 23:00 were taken as daytime blood pressure readings, whereas readings obtained between 23:00 and 07:00 were considered night-time blood pressure. Dippers were considered to be those patients in whom the difference between mean daytime systolic/diastolic blood pressure and mean night-time systolic/diastolic blood pressure was 10/5mm Hg or more.

Results: Thirty-six (72%) and 14 (28%) patients with essential hypertension fulfilled the criteria for dippers and non-dippers, respectively. The night-time systolic and diastolic blood pressures were significantly higher in non-dippers than in dippers (P < 0.05). The mean daytime systolic and diastolic blood pressures were not different between these two groups. Twenty-nine out of 36 (80.6%) urinary specimens from dippers were without microalbuminuria, against six out of 14 (42.9%) specimens from non-dippers, p < 0.05. Eighteen out of 20 controls (90%) were without microalbuminuria.

Conclusion: This study demonstrated that about 28% of the local essential hypertensive population was non-dippers and 57.1% of these had microalbuminuria with the attendant cardiovascular and renal risks.