Context: Pubertal timing in boys is associated with body mass index (BMI). Studies consistently report an inverse correlation of BMI and pubertal timing within the normal BMI range. However, observations in obese boys are conflicting with different studies reporting either early or delayed pubertal onset in obese boys.
Objectives: We aimed to assess the association of clinically assessed initial milestones of male puberty, i.e. gonadarche, testicular enlargement and pubarche, with age-specific BMI (zBMI) in obese boys.
Participants & Methods: Cases: 254 obese boys (zBMI >2SD, median age at baseline 11.2 (range: 4.2 to 17.4) were recruited as part of an outpatient childhood obesity intervention program at Nordsjællands Hospital, Denmark between 2009 and 2017. Controls: 127 overweight (zBMI >1SD and ≤2SD) healthy boys participating in The Copenhagen Puberty Study (entire cohort: n = 731, zBMI range: -2.5 to 2.5 SD, mean age in yrs (95%CI) at gonadarche 11.6 (11.5-11.7), testicular volume ≥ 4mL 11.6 (11.5-11.8), pubarche 12.2 (12.1-12.4)) [Sørensen et al., JCEM 2009]. Baseline clinical assessment of pubertal development by Tanner staging including testis volume using a Prader orchidometer was performed by trained physicians in 244/254 boys. Timing of pubertal milestones was estimated by probit analyses.
Results: Age at pubertal onset was similar between obese boys (zBMI >2SD) and overweight controls (zBMI >1SD and ≤2SD): mean (95% CI) gonadarche at 11.6 yrs (11.3-11.9) vs 11.5 (11.1-11.9) yrs, P=n.s.; testicular volume ≥ 4mL at 11.2 (11.0-11.5) vs 11.4 (11.0-11.8) yrs, P=n.s.; and pubarche at 11.9 (11.5-12.3) vs 11.8 (11.3-12.3) yrs, P=n.s., respectively. In the obese cohort, median (range) zBMI at Tanner staging was 3.2 (2-6.3). In obese boys, zBMI was not associated with onset of any of pubertal milestones.
Conclusion: We demonstrate that obesity in boys is not associated with delayed pubertal timing compared to overweight boys. However, it appears that the strong negative association between BMI and age at pubertal onset that is usually observed in boys within the normal BMI range, is attenuated in obese boys.
19 - 21 Sep 2019
European Society for Paediatric Endocrinology