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

Abstract

Previous studies have indicated that Japanese children grow and mature significantly faster than Caucasian children, thus calling for a separate reference standard for each skeletal and sexual maturity index. To establish normal reference values for testicular volume in Japanese boys, we studied from 1985 to 1995, 900 healthy male children of 0 to 15 years of age for medical 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 same observer (N.M.). Based on these data, we established the cross-sectional percentile growth curves (90th, 50th, 10th percentiles) for testicular volume of Japanese boys. The testicular volume of 3 ml was attained at 9.3 years of age (90th percentile), 11.0 years of age (50th percentile), and 12.1 years of age (10th percentile), respectively. Swelling of the testis in Japanese children begins approximately 1 year earlier than in Swiss children in accordance with the earlier skeletal maturation in Japanese children.