Testicular volume in Japanese boys up to the age of 15 years

Previous studies have indicated that Japanese children grow and mature sign ificantly faster than Caucasian children, thus calling for a separate refer ence standard for each skeletal and sexual maturity index. To establish nor mal reference values for testicular volume in Japanese boys, we studied fro m 1985 to 1995, 900 healthy male children of 0 to 15 years of age for medic al history, physical examination, height, weight, sitting height, and head circumference measurements, Tanner sex maturity stage, and testicular size. The testicular volume was determined using a Prader orchidometer by the sa me observer (N.M.). Based on these data, we established the cross-sectional percentile growth curves (90th, 50th, 10th percentiles) for testicular vol ume of Japanese boys. The testicular volume of 3 mi was attained at 9.3 yea rs of age (90th percentile), 11.0 years of age (50th percentile), and 12.1 years of age (10th percentile), respectively. Conclusion Swelling of the testis in Japanese children begins approximately 1 year earlier than in Swiss children in accordance with the earlier skele tal maturation in Japanese children.