Tanner stages and Prader orchidometry in male adolescents. A descriptive, cross-sectional study

Introduction. The Tanner scale and the Prader orchidometer are the instruments most commonly used to assess pubertal development in children. The assessment of puberty in the clinic is only useful if recent and reliable references in the same population are available for comparison. Objective: to assess the correlation between Tanner stages and testicular volume (TV) in Argentine adolescents. Population and methods. Study with a descriptive, cross-sectional design conducted in healthy boys aged 9-20 years. Male children and adolescents with urogenital conditions and disorders affecting testicular growth were excluded. The correlation between Tanner stages and TV was assessed using non-parametric tests. Results. A total of 367 male adolescents with an average age of 13.8 ± 2.5 years were assessed. TV increased in correlation to Tanner stages (Spearman: 0.943, p < 0.001) with significantly different  volumes, except in the early genital 1-2 stages (p 0.343) and pubic hair 1-2 stages (p 0.447). Among peripubertal boys, 16% (95% confidence interval: 9.6-24.4%, n = 17/106) were wrongly classified based on Tanner stages. Conclusions. During  male  puberty,  TV  increased  in  correlation  to  Tanner  stages,  but  no  significant differences were observed between Tanner stages 1 and 2. Using the Prader orchidometer is critical to establish the onset of puberty in boys.