La pubertad en niños chilenos muestra un adelantamiento en el inicio del crecimiento testicular / Age of onset of puberty in Chilean boys according to testicular volume and Tanner stage

Background: A secular trend towards a younger age of puberty onset has been reported in Chilean girls. Aim: To evaluate the age of onset of puberty and prevalence of early puberty in Chilean boys. Material and Methods: A pediatric endocrinologist examined 319 children attending schools in central Santiago. Pubertal development was assessed by testicular volume (TV) and genital inspection (GI) using Tanner graduation. Precocious and early puberty development was diagnosed if TV ≥ 4 ml or GI > stage 2 occurred in boys younger than 9 years and at 9-10 years of age, respectively. Results: Pubertal onset occurred at 10.2 ± 1.5 years according to TV and at 11.1 ± 1.6 years according to GI (p < 0.01). Before the age of nine, 15.2% of children had a VT ≥ 4 ml, 3% had genital changes in GI and only 3% had both changes simultaneously. Early puberty was observed in 23.8% of children according to TV and 9.5% according to GI. However, no child of less than 11 years old had a TV ≥ 4 ml, genital changes and pubic hair simultaneously. Late pubertal stages occurred at the same age according to both criteria used. Body mass index z score was not associated with the age of pubertal onset. Conclusions: Testicular enlargement occurs one year earlier than changes in genitalia according to inspection. Testicular growth, but not late stages of puberty, are occurring one year earlier than previously reported in Chile 10 years ago.

Edad de la menarquia y su relación con el nivel socioeconómico e índice de masa corporal / Age of menarche and its relationship with body mass index and socioeconomic status

Background: A decline in the age of menarche was observed from early 1900s to the 1970s. However, it is not known if a further decline ocurred thereafter. Aim: To evaluate the age of menarche in girls from Santiago, Chile and its relationship with body mass index (BMI) and socioeconomic status. Material and Methods: We studied 1302 healthy girls aged 7 to 19 years. Age of menarche was evaluated through a questionnaire to the patient and her parents. Kaplan-Meier curves were used to determine age of menarche and Cox regression analysis was employed to evaluate the effect of the type of school and BMI on the age of menarche. Results: The mean age at menarche was 12.7±0.04 years. Girls from public and private schools had their period at 12.5±0.1 and 13.05±0.05 years respectively. A negative correlation between z scores for BMIand age of menarche was observed (r-0.3: p =0.001). Girls whose menarche occurred before 11.5 years had higher z scores for BMI and a larger proportion were overweight, compared to girls who had menarche later. Cox regression analysis showed that after adjusment for BMI, age of menarche was similar in both types of schools. Conclusions: Age of menarche is ocurring three months earlier in girls from public schools, which is associated with higher z scores for BMI. Type of school, a marker of socio-economic status in Chile, affects timing of menarche due to differences in body mass index.