1. Presentation
The characteristics of the patients and the percentages of increased values are shown in Table and Fig and . The age at onset of CPP was less than 3 years in 7 patients (2%), but their characteristics (Table ) were similar to those of the others. It was 3–7 years in 133 (38%) patients and 7–8 years in 213 (60%).
| Table 1Presentation of 353 girls with idiopathic CPP. |
| Table 2Characteristics of 7 girls with idiopathic CPP beginning before 3 years |
Breast development was stage 2 in 47% of cases and greater in the others. This development was isolated in 70 (20%) cases and associated with other clinical signs suggesting CPP in the remainder.
Of the 70 patients with isolated breast development, 39 were diagnosed as having CPP at presentation, with a uterus length of ≥ 35 mm (16/31), a LH/FSH peaks ratio of ≥ 0.66 (25/68) and/or plasma estradiol concentrations ≥ 15 pg/mL (18/67). The clinical picture of CPP in the other 31, aged 3.2–7.9 years, became complete during the year following the initial evaluation. They were compared to those with other signs at presentation: their ages at puberty were similar, as were the intervals between the onset of puberty and the initial evaluation, but their BMIs were lower (0.9 ± 1 SDS; others 1.3 ± 1.4 SDS, P < 0.05), their weight increased less during the previous year (3 ± 1.2 kg; 3.9 ± 1.4 kg, P < 0.0001), their plasma estradiol concentrations were lower (14 ± 13 pg/mL; 20 ± 17 pg/mL, P < 0.004), as were their LH peaks (7.1 ± 7.2 IU/L; 12.2 ± 15.1 IU/L, P < 0.02) and LH/FSH peaks ratios (0.5 ± 0.5; 0.9 ± 0.9, P < 0.005).
The pubic hair development was stage 1 (n = 120, 33%), stage 2 (n = 130) or greater (n = 103). The ages at puberty and at presentation and the BMIs of girls without pubic hair development were similar to those with stage P2, but their bone age was less advanced (0.8 ± 1.1; P2 1.3 ± 1.3 years, P < 0.006). Those with a lower BMI had a lower DHAS (357 ± 259 ng/mL) than those with a BMI greater than one SDS (481 ± 344 ng/mL, P < 0.03).
The increase in weight during the previous year (3.7 ± 1.4 kg, n = 267) was positively correlated with the height and bone age advance (P < 0.0001 for all), but not with estradiol, LH peak, or the LH/FSH peaks ratio. The bone age advance was positively correlated with the BMI, statural growth rate and estradiol (P < 0.0001 for all).
2. Presentation factors
The characteristics of the patients (Table ) were compared according to their age at puberty, the interval between the onset of puberty and evaluation, BMI and the presence of familial CPP. The patients aged 3–7 years were taller (2.2 ± 1.4 SDS) than those aged 7–8 years (1.9 ± 1.2 SDS, P < 0.01), while their bone age advance was similar.
When the patients were classified according to whether the interval between the onset of puberty and evaluation was greater than or less than 0.9 year (mean interval), there was no difference in their characteristics. When they were classified according to their BMI (below or above 2 SDS, 25.3%), those with the lower BMI were shorter (1.9 ± 1.3 SDS; higher BMI 2.5 ± 1.3 SDS, P < 0.0001). The difference was similar with a limit of BMI at the mean. When they were classified according to the year of presentation (intervals of 5 years from 1984 to 2006), the BMI (SDS) varied from 1.1 ± 1.5 (n = 48) in the oldest, to 1.5 ± 1.5 (n = 51), 1.3 ± 1.2 (n = 125) and 1.0 ± 1.4 (n = 127) in the youngest.
The age at menarche of the mothers was < 10 years in 4% and < 11 years in 27% of cases. Their characteristics, and those of the 5% who were adopted, were similar to those of the others.