Sex-related influence of body size and sexual maturation on blood pressurein adolescents

Objective: This study is aimed at investigating the influence of body size, body fat and sexual maturation on blood pressure (BP) in adolescents. Design: A cross-sectional study. Setting: A suburban student population of Southern Italy. Subjects: One hundred ninety students attending the first and second year o f a secondary school. Five were excluded because they were affected by majo r diseases. The remaining were 98 M and 87 F (mean age for either group = 1 2.0 +/- 0.8 y). Methods: Blood pressure was measured by a mercury sphygmomanometer, body we ight by a platform beam-scale, other measurements included height, biceps, triceps, subscapular and suprailiac skinfolds by a caliper; sexual maturati on was evaluated according to Tanner. Results: Body size was greater than in Tanner's population: in particular b ody weight (but not height) in our sample markedly exceeded that of the chi ldren of the same age in Tanner's population. Boys had higher systolic bloo d pressure (SBP) than girls (BP = 109/64 +/- 12/10 vs 103/63 +/- 11/8 mmHg, P < 0.02 for SEP), while heart rate and waist/hip ratio were lower. During puberty-evaluated on the basis of pubic hair growth-BP in girls was higher than in the prepubertal phase (107/66 +/- 9/7 vs 99/61 +/- 10/7, P < 0.01). Pubertal boys showed a reduced percent of body fat (calculated from four skinfold measurements) in comparison to prepubertal ones (21.0% +/- 4 .5 vs 24.50% +/- 7.1, P < 0.01). In linear correlation analysis, height, BW , BMI and lean body mass were found to be significantly associated with SEP in both sexes and to diastolic blood pressure (DBP) in girls. Percent body fat was correlated with SEP in boys, while sexual maturation was associate d to SEP and DBP in girls only. Multiple regression analysis indicated a si gnificant contribution of body size to BP variability, particularly in the girls. Sexual maturation was excluded from the final regression equations w hen height, BW or lean body mass were present. Conclusions: These data indicate that body weight in these adolescents is g reater that in Tanner's population of the same age and sex. Body size appea rs to be a major determinant of BP, whereas sexual maturation seems to infl uence BP levels mainly through body growth. The influence of percent body f at on BP setting seems to be of limited importance.