Change scores between baseline and final visit for testicular volume and stretched penile length z scores were compared between treatment groups. Mean testicular volume increased to 3.6 ± 2.2 mL in the Ox group compared with 2.2 ± 1.8 mL in the Pl group (P = 0.016). Stretched penile length increased to 6.2 ± 1.5 cm in the Ox group and 5.4 ± 1.4 cm in the Pl group, with corresponding z scores to adjust for the age differences depicted in the figure on the right (P = 0.003).