Objective: Recent studies have suggested earlier onset of pubertal development in boys. As assessment with orchidometer tends to overestimate true testicular volume (TV), and measurements based on ultrasound (US) have been proposed as a more reliable method, we present US based references in 6-16 year-old Norwegian boys. Our results are compared with data from Europe and the United States (U.S.) in order to establish evidence for an ongoing secular trend in male pubertal timing.
Methods: TV was measured by ultrasound in a cross-sectional study of 514 healthy boys (mean age 11.0 year, range 6.1-16.4) and reference curves were constructed using the LMS method. Tanner pubic hair (PH) staging was clinically assessed in 453 boys (mean age: 10.9 years, range: 6.1 to 16.3). Pubertal development was determined in terms of selected TV cut points or the PH stages and related to age using simple probit regression models.
Results: US testicular volume of 2.7 ml, corresponding to orchidometer definition of puberty onset volume of 4 ml, was on average reached at mean (standard deviation: SD) 11.7 (1.1) years with the 3rd and 97th percentile at 9.7 and 13.7 years, respectively. TV by age was positively skewed. Mean age (SD) for reaching Tanner PH stage 2 was 11.8 (1.2) years with 3rd and 97th percentile at 9.5 and 14.1 years, respectively. Our findings were highly comparable with previous published data from Europe and the U.S.
Conclusion: New references for TV measured by US and equivalent orchidometer volumes were constructed together with pubic hair references. US provides a continuous measure allowing for accurate SD score calculations. No secular trend in pubertal development in boys was observed indicating that the definition of normal pubertal onset in boys between 9 to 14 years remains statistically valid.
19 - 21 Sep 2019
European Society for Paediatric Endocrinology