Circadian blood pressure variation versus renal function

Several published reports describe an abnormal circadian blood pressure profile in chronic renal failure subjects. Factors other than renal failure, including age, diagnosis of diabetes mellitus, autonomic dysfunction, and race, also may affect circadian blood pressure profiles. To further elucidate the relationship between renal function and circadian blood pressure variation, we compared day/night circadian blood pressure changes in three groups of male veteran hypertensive patients: group A, creatinine clearance (CC) > 80 mL/min, n = 20; group B, CC 20 to 80 mL/min, n = 19; and group C, CC < 20 mL/min, n = 14. We use postural changes in catecholamines, renin, and aldosterone as a measure of autonomic function. No significant difference in day/night percent change in systolic, diastolic, mean arterial pressure (MAP), or heart rate was seen by renal function group. Regression analysis using age, diagnosis of diabetes mellitus, postural hormonal changes, and creatinine clearance found race to be the only significant predictor of the day/night percent change in MAP (P < 0.05). Compared with whites, black subjects had higher nocturnal heart rates (P = 0.01); smaller day/night heart rate changes (P = 0.03); significantly higher diastolic blood pressure (P = 0.01); and a trend toward smaller day/night change in diastolic blood pressure (P = 0.06). In conclusion, renal function level does not influence day/night blood pressure changes. The blunting or reversal of the normal circadian blood pressure pattern seen in some chronic renal failure hypertensive subjects may be attributable to the association between chronic renal failure and cofactors associated with abnormal circadian blood pressure, including black race and possibly severity of atherosclerosis.