Sex-related influence of body size and sexual maturation on blood pressure in 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 of a secondary school. Five were excluded because they were affected by major diseases. The remaining were 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 beamscale, 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 mm Hg, 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. CONCLUSIONS: 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, whereas 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.     

女童青春期线性生长与性发育时相的定量关系研究

目的 探讨女童青春期线性生长与性发育时相的定量关系,为青春期身高评价提供参考依据。方法 采用分层随机整群抽样的方法,对北京市城区和郊区的9 630名6~19岁女童进行横断面调查,内容包括身高、体重、第二性征和月经初潮年龄,采用Person相关方法分析性发育与身高的相关性、t检验和方差分析方法比较各个性发育时相身高的差别。结果 1)性发育进程与身高水平呈正相关,尤其9~12岁更为明显(相关系数为0.41~0.55)。2)处于性发育不同时相的同龄儿身高存在明显差别,如8~12岁性发育前期者比性发育中期者身高平均低5~7 cm、11~13岁性发育中期者比同龄性发育后期者平均低4~6 cm;按年龄别身高标准计算身高百分位数值,性发育前期比性发育中期身高低约17~27个百分位,中期比后期低13~23个百分位。3)与未考虑性发育特征的身高曲线比较,8~9岁性发育处于中期、10~12岁性发育处于后期的女童,其身高明显高于相同年龄的平均身高约12~24个百分位;而10~11岁性发育前期、12~13岁性发育中期者身高明显低于同龄女童平均身高约10~30个百分位。结论 处于性发育不同时相的同龄女童身高存在明显差别,应用生长曲线图进行身高评价可根据性发育时相上调或下调一条曲线粗略校正性发育对身高的影响。     

贵阳市1 867名12～17岁女童性发育与血压关系

目的研究青春期女性性发育与血压的关系,以便为青少年生长发育的研究提供依据.方法 2002年9～11月对贵阳市12～17岁女童1 867名进行性发育评价,测量身高、体重、收缩压、舒张压和心率.结果同年龄、不同性发育水平(月经来潮与否),收缩压、舒张压均有随乳房和/或阴毛发育水平的增加而逐渐升高的趋势;但在同一乳房和/或阴毛发育水平时,上述2项指标并未呈现来潮者高于未来潮者的趋势.不同年龄、同一性发育水平时,除在性未发育个体的2项指标均有随年龄增长而增高的趋势外,其他性发育水平(月经来潮与否)的2项指标均未见有明显的规律性增加或下降.结论综合考虑性发育水平可较好地反映青春期女性个体的血压变化.     

婴儿期生长情况对青春期性发育的影响研究

目的 探讨婴儿期快速生长对青春期性发育的影响,对预防未来青春期提早发育提供依据。方法 选择2004年1月-2005年1月在温州市儿童医院及本院体检的198例生长过快的婴儿为观察组,另选择175名正常婴儿为对照组。根据出现月经初潮/遗精的时间点,把观察组分成性早熟组和正常发育组。采用Spearman相关性分析观察组婴儿1周岁的身高Δ值、体重Δ值与青春期性早熟的相关性。结果 观察组婴儿1周岁的身高Δ值、体重Δ值均显著大于对照组,差异有统计学意义(t＝2.085,2.146,P＜0.05);观察组儿童的身高、体重、体脂、骨龄值均显著大于对照组儿童,观察组儿童的T、E2、FSH、LH水平均显著高于对照组儿童,差异均有统计学意义(P＜0.05)。对照组无性早熟患儿。观察组、早熟组和正常组的男女比例对比,差异无统计学意义(P＞0.05)。早熟组身高、体重、体脂、骨龄值均显著大于正常组,早熟组T、E2、FSH、LH水平均显著高于正常组,差异有统计学意义(P＜0.05)。观察组婴儿1周岁的身高Δ值、体重Δ值与青春期性早熟呈正相关(r=0.816,0.872,P<0.001)。结论 婴儿期快速生长可造成儿童青春期前肥胖和体脂过度,使青春期早发。控制婴儿期过快生长对预防未来青春期提早发育有重要意义。     

Somatotype, physical growth, and sexual maturation in young male smokers.

One thousand school boys aged 8 to 16 were examined for their somatotype, physical growth, sexual maturation, and smoking habits. Fifty-two boys were found to be smokers, of whom 30 were regularly smoking between two and 20 bidis or cigarettes a day for a mean duration of 2.5 years. The mean height and weight of the smokers was significantly lower than that of the non-smokers at all ages, more so in regular than occasional smokers. Sixty-nine per cent of the smokers had mesomorphic type of body build; about 65% of the non-smokers had ectomorphic somatotype (P less than 0.001). Onset of puberty occurred significantly earlier among smokers compared with non-smokers, as was evident from the early appearance of genital stage 2, and an early and rapid increase in testicular size. Genital stage 2 appeared at a mean age of 11 years in smokers and 11.6 years in non-smokers. However, the appearance of pubic, axillary, and facial hair was delayed. The possible significance of this is discussed.     

Osteocalcin. A biochemical marker of bone turnover during puberty

During bone remodelling, osteocalcin is produced by osteoblasts and its level increases during the events characterized by rapid bone turnover. Osteocalcin is a bone matrix protein, which is specific for bone metabolism and it is not influenced by metabolic bone disorders. Osteocalcin is an important marker of bone turnover in physiological and pathological conditions. Physiologically, serum osteocalcin was increased in children, particularly during the first year of life and during puberty, when evolution of the concentration was related to rapidity of physical growth. Evidence of a correlation with growth rates comes from the observation that serum osteocalcin levels parallel the height velocity curve, with higher values in childhood and during adolescence, that later fall to adult values. There are previous studies reporting that there is age- and sex-dependent change in serum osteocalcin levels in children and adolescents with a pattern resembling height velocity curves for children and serum osteocalcin elevation coincides with the pubertal growth spurt. These findings demonstrate that pubertal development and sex should be taken into account rather than chronological age when serum levels of osteocalcin are evaluated. In most of the studies relationships among osteocalcin and chronological age and bone age, but not pubertal developmental stage (sexual maturation stage) were investigated. The aim of our study was to determine whether osteocalcin is a useful marker for the pubertal growth spurt period. In this study, osteocalcin levels in male adolescents were examined in relation to their sexual maturation stage and age. According to our findings, the follow up of osteocalcin levels in relation to sexual maturation stages could be a new method to determine the phase of the pubertal growth spurt. An increase or decrease in osteocalcin levels on consecutive measurements may indicate the child's entering accelerated or decelerated stages of the growth spurt, respectively. We emphasize that the follow up of adolescent growth is made by determination of the sexual maturation stage, and not by age. Osteocalcin is a highly specific, reliable and useful marker for evaluation of the growth spurt and is not influenced by nonosseous disorders.     

青春期学生血压变化规律分析

目的了解青春期学生血压变化规律,为儿童青少年血压标准的制定与评价提供依据。方法采用中山市2005-2010年学生体检资料,经匹配个人信息后形成2 690人的队列数据,描述调整身高增速高峰年龄前、后儿童血压水平和血压增长速率变化情况。结果进入青春期后,男、女生血压增速明显增加,增加起始于身高增速高峰年龄前1～2 a,身高增速高峰年龄时增速达到最高峰,从血压增长加速到回落需3～4 a;女生血压增长加速较男生早2～3 a,男生血压增速幅度高于女生,增速回落较女生缓慢。使用调整身高增速高峰年龄的方法分析青春期血压的变化规律,优于直接分析各年龄血压水平。结论青春期学生血压增长速率明显增加,男、女生情况有所不同。     

International collaborative study on juvenile hypertension 1. Study procedures and screening data

The study procedures and the results of blood pressure screening from 8 centres are reported. Data are also presented on age, sex, sexual maturity for girls, height, weight, Quetelet''s index, smoking, and use of antihypertensive drugs for 92.1% of the 18 609 children born in 1964 in the 8 districts and surveyed in 1977. The girls who had reached sexual maturity had the highest means for blood pressure, height, weight, and Quetelet''s index. The proportion of girls who had attained menarche differed geographically. Certain differences were found among the 8 centres in the variables measured, but when age-specific comparisons were made most of the differences in the variables disappeared. Nevertheless a lower systolic blood pressure and height and a higher pulse rate were observed in Havana, Cuba, than in the European cities. Using multivariate analysis, height, weight, pulse rate, age at survey, and sexual maturity together explained somewhat less than 20% and 10% of the variation of systolic and diastolic blood pressures, respectively. These screening data provide a baseline for a longitudinal study that will continue until 1982.