Pubertal testicular volume references for ruler, orchidometer, and ultrasonography measurements based on a longitudinal follow-up.

Abstract

Testicular volume is a marker of male pubertal development. Various clinical conditions and their treatments may influence testicular growth. To create ruler-based age-dependent pubertal testicular volume references that enable calculation of standard deviation (SD) scores. Study cohort comprised 65 boys who attended clinical examination twice a year from the age of 8.5 years until the attainment of final testicular size. Forty-nine (75.4%) boys completed the follow-up and 16 (24.6%) boys dropped out before the attainment of final post-pubertal testicular size. At each follow-up visit testicular size was measured with a ruler, orchidometer, and ultrasonography. LMS or LMSP method served as the technique for creating reference growth curves for testicular volumes. Using the novel references for ruler measurements, development of SD scores was assessed in a cohort of boys with unilateral cryptorchidism. Reference growth curves were constructed separately for ruler, orchidometer, and ultrasonography measurements. Median orchidometer volume of 4mL, marker of male pubertal onset, occurred at the age of 11.7 years, whereas +2SD curve surpassed 4mL at 10.2 years and -2SD curve at 13.7 years. Modeled ages at the attainment of 4mL testicular volume based on ruler measurements were 9.7 years for +2SD curve, 11.5 years for median curve, and 13.6 years for -2SD curve. Ultrasonography-based volume of 1.3mL corresponded with the median modeled orchidometer-based volume of 4mL. In boys with unilateral cryptorchidism, ruler-based SD scores decreased during puberty in undescended testes, but not in descended testes. The present study provides reference values for pubertal testicular volume measured with a ruler enabling an age-dependent assessment of testicular size. Comparison with measurements by an orchidometer and ultrasonography is also presented.