Nighttime blood pressure fall in renal disease patients

There are controversial reports in the prevalence of abnormal nighttime blood pressure fall in renal patients. It has been evaluated nocturnal BP in renal patients using 24 h blood pressure monitoring (ABPM) in comparison with nontreated control subjects either normotensives or hypertensives.

It has been reviewed 137 ABPM studies performed in renal patients (47.8 +/- 15.4 years, 76 men and 61 women). The control group includes 119 subjects without kidney disease, 65 were normotensives, and 49 were hypertensives, aged 46.8 +/- 12.1 years, 59 men and 60 women. The ambulatory BP was measured noninvasively for 24h by the SpaceLabs 90207 device programmed to measure BP every 15 min during daytime and every 20 min during nighttime. The definition of daytime and nighttime was made on the basis of wakefulness and sleep or bed rest periods, obtained from a diary kept by each subject.

SBP, but not DBP, was higher (133.9/81.7) in renal disease patients when compared to nonrenal subjects (127.9/80.8, p < 0.01). When the control group was split into normotensive and hypertensive patients there were still significant differences, but hypertensives had higher BP than renal disease patients (139.0/89.7, p < 0.05). Nocturnal SBP fall in renal disease patients was reduced (5.8%, p < 0.001) and so was DBP fall (11.1%, p < 0.001) compared with the overall nonrenal patients sample (SBP 10.8; DBP 15.3%). The frequency of nondipper status in renal disease patients (39.6%) was higher than in control patients (18.4%, p < 0.001). Nontreated normotensive renal disease patients did not show any difference in either SBP or DBP nighttime fall with respect to control normotensives. Neither do nontreated hypertensive renal patients as compared with control hypertensives. There were not differences between proteinuric and nonproteinuric patients in nocturnal BP fall. The same result was obtained when hypertensive and normotensive nontreated renal patients were compared. The presence of renal failure did not induce a reduction of nocturnal BP fall. Most of treated renal patients were mainly receiving drug therapy during the morning and frequently this was the single daily dose.

Altered diurnal rhythm should not be considered as a usual complication of renal disease. Inadequate antihypertensive pharmacotherapy could be related to the abnormalities of nighttime BP fall when it is detected.