Constitutional Isosexual Precocious Puberty

Abstract

Introduction In the syndrome of idiopathic isosexual precocious puberty, events similar to those which occur at puberty occur at an abnormally early age.^1-3 The selection of ages demarcating "normal" from "precocious" may be based on the observations of Nicolson and Hanley,4 who found the earliest pubertal changes in North American girls (breast budding) to occur at a mean age of 10.6 years with a standard deviation of 1.2 years. In boys, the mean age for the earliest pubertal change (enlargement of the external genitals) was 11.8 years with a standard deviation of one year. Assuming a normal frequency distribution, abnormal or precocious development may be defined as development beginning more than three standard deviations earlier than the mean age or 7 years in girls and 8.8 years in boys. This definition excludes some of the patients included by other writers^1-3,5 but, in view of available information in this