Circadian variation of urinary microalbumin excretion and ambulatory blood pressure in patients with essential hypertension

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ObjectiveTo investigate the relationship between circadian changes in urinary microalbumin excretion (UAE), blood pressure (BP) and physical activity in patients with essential hypertension.Design and methodsThe subjects were 45 patients with essential hypertension (EH group: 26 male and 19 female, age 56 ± 12 years (mean ± SD)) and 25 patients with diabetes mellitus (DM group: 14 male and 11 female, age 61 ± 10 years). Their BP and physical activity (acceleration) were measured at 30-min intervals for 24 h by means of a multi-biomedical recorder (TM2425). Urine samples were collected during each of four 4-h daytime periods and one 8-h night-time period. From these samples, per-h UAE (UAE/h) was measured. Mean values for mean blood pressure (MBP) and acceleration were calculated for corresponding time periods. Plasma hormones were measured during an early morning rest period.ResultsIn the EH group, a significant positive correlation was observed between circadian variation of UAE/h and MBP in 35 (78%) subjects, and the mean coefficient of correlation (r) was 0.86 ± 0.12. A significant positive correlation was observed between circadian variation of UAE/h and mean acceleration value (Gh) in 25 (56%) subjects, and the mean r value was 0.70 ± 0.26. Multivariate linear regression analysis showed that MBP exerted a greater influence on UAE/h than Gh. Significant positive correlations were observed between UAE/day and plasma human atrial natriuretic peptide and plasma aldosterone concentration (r = 0.50, P < 0.01; r = 0.36, P < 0.05). None of these relations, however, was observed in the DM group.ConclusionsIn patients with essential hypertension, circadian changes in activity and variation of BP influence UAE/h, but no definite relationship of this kind was observed in patients with diabetes mellitus. Measurement of circadian changes in UAE or UAE/day may be useful in estimating the degree of daily stress in non-diabetic patients with essential hypertension.

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