An analysis of predictive factors for the conversion from premature thelarche into complete central precocious puberty.

AIM: To determine the predictive factors for the conversion of premature thelarche (PT) into complete central precocious puberty (CCPP) in girls.
DESIGN: Prospective.
METHODS: One hundred and fifty-one girls with PT referred consecutively for evaluation of clinical, laboratory, and ultrasound data.
RESULTS: Twenty-one and a half percent of girls with PT converted into CCPP at a chronological age of 7.1 +/- 0.7 years and bone age of 9.0 +/- 1.1 years. Using logistic regression analysis, longitudinal diameter of uterus (OR = 1.215), Tanner breast stage at the time of first physical examination (OR = 3.334) and regression of breast development (OR = 3.921) were the most significant variables predicting the conversion from PT into CCPP. Compared with the non-converted group, the converted groups had larger breast size at the time of diagnosis (z = 2.077, p = 0.038). A total of 69.5% (105/151) of patients experienced complete regression of breast development, 13.2% (14/105) of whom converted into CCPP; 21.5% (31/151) of patients had recurrent breast development, 32.3% (10/31) of whom converted into CCPP; 10% (15/151) of patients had constant breast development, 56.7% (7/15) of whom converted into CCPP, with the highest rate among the three breast development categories (chi2 = 12.23, p = 0.002).
CONCLUSION: PT is not often a self-limited condition and may sometimes convert into CCPP. The predictive factors for conversion were related to estrogen exposure including longitudinal diameter of the uterus, Tanner breast stage at the first consultation and the regressive categories of breast development.