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

Ojective: 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 of a secondary school. Five were excluded because they were affected by major diseases. The remaining 98 M and 87 F (mean age for either group = 12.0 +/- 0.8 y). Methods: Blood pressure was measured by a mercury sphygmomanometer, body weight by a platform beam-scale, other measurements included height, biceps, triceps, subscapular and suprailiac skinfolds by a caliper: sexual maturation was evaluated according to Tanner. Results: Body size was greater than in Tanner's population: in particular body weight (but not height) in our sample markedly exceeded that of the children of the same age in Tanner's population. Boys had higher systolic blood pressure (SBP) than girls (BP = 109/64 +/- 12/10 vs 103/63 +/- 11/8 mmHg, P < 0.02 for SBP), 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 24.5% +/- 7.1, P < 0.01). In linear correlation analysis, height, BW, BMI and lean body mass were found to be significantly associated with SBP in both sexes and to diastolic blood pressure (DBP) in girls. Percent body fat was correlated with SBP in boys, while sexual maturation was associated to SBP and DBP in girls only. Multiple regression analysis indicated a significant contribution of body size to BP variability, particularly in the girls. Sexual maturation was excluded from the final regression equations when height, BW or lean body mass were present. Conclusion: These data indicate that body weight in these adolescents is greater that in Tanner's population of the same age and sex. Body size appears to be a major determinant of BP, where sexual maturation seems to influence BP levels mainly through body growth. The influence of percent body fat on BP setting seems to be of limited importance.