Ambulatory blood pressure and renal function in healthy children and adolescents

Our previous studies using noninvasive ambulatory blood pressure (ABP) monitoring demonstrated racial differences in the diurnal pattern of blood pressure (BP), with higher nighttime BP for African-Americans than for Anglo-Americans despite similar daytime BP. We have hypothesized that the increased BP load in African-Americans contributes to the increased prevalence of hypertension and BP-induced target organ damage in adults. The purpose of this study was to examine the relationship between ABP patterns and renal function in healthy, normotensive black and white youths. The subjects were 22 African-American and 28 Anglo-American children and adolescents aged 10 to 18 years. Renal function was estimated by creatinine clearance (CCr). The African-American and Anglo-American subjects were similar in age, gender composition, casual BP, and CCr. The relationship between CCr and BP was not significant for casual BP or daytime BP for either group, or with nighttime BP in the Anglo-American subjects. In contrast, CCr was related negatively to both nighttime systolic BP (r = -0.47, beta = -1.21; P < .02) and nighttime diastolic BP in the African-American subjects (r = -0.45, beta = -2.13; P < .03). These results are consistent with our hypothesis.