Blood pressure and urinary sodium in black American adolescents

For 56 black American adolescents ranging in age from 13 to 19 years, 24-hour urinary sodium excretion was compared with blood pressure. The volunteers came from families of middle to low economic levels. Their body weight varied from 70 to 129 percent of ideal body weight. The average systolic pressure of all the subjects was 112.1 mmHg with a standard deviation of 9.5 mmHg; mean diastolic pressure was 69.6 mmHg with a SD of 8 mmHg. The average 24-hour urinary sodium excretion of the total population was 131.5 mEq/24 h with a SD of 59 mEq. For the 29 male subjects, the mean value was 137 mEq/24 h (range, 30 to 309 mEq) and for 27 female subjects, 126.3 mEq/24 h (range, 40 to 197 mEq). The average urinary excretion among these groups was not significantly different (P > .05) and the urinary Na/K ratio of the total group was 4.3 with a SD of 2.0. This ratio among various age and sex subgroups was not significantly different (P > .05). Urinary sodium excretion values were taken as a reflection of dietary salt intake among these volunteers. The data suggest that the black adolescents studied do not consume excess sodium and contradict the belief that blacks eat excess sodium. Further, these baseline data must be considered among the factors responsible for the development of hypertension.