Factors predicting final height in early treated congenital hypothyroid patients

Objective: To evaluate pubertal development and final height (FH) in early treated patients with congenital hypothyroidism (CH) and to identify the main factors predicting FH. Design: Retrospective. Patients: Eighty-five patients with early diagnosed and treated CH. Measurements: Evaluation of length/height at diagnosis (mean age 26.6 days), at onset of puberty, and at the end of linear growth. Results: Mean FH was 161.7 cm in females and 173.8 cm in males, within ± 0.9 cm of the 50th percentile of Italian growth charts, 5 cm higher than the mean target height (TH). Linear growth did not differ according to thyroid imaging findings. In males, height at onset of puberty was 0.16 standard deviation score (SDS), not statistically different from FH (-0.09 SDS). In females, height both at onset of puberty (0.39 SDS) and at menarche (0.57 SDS) was significantly higher (P < 0.001) than FH (-0.10 SDS). Puberty started at a mean chronological age of 10.2 and 11.6 years in females and males, respectively, with a corresponding bone age. FH correlated with TH and height at diagnosis, at onset of puberty, and at menarche. Multiple regression analysis showed that height at onset of puberty and TH are the most important factors explaining FH variability, although height at onset of puberty is slightly more important. Conclusions: Our results, obtained in the largest reported available group of congenital hypothyroid patients, show that final height is higher than target height in both sexes and that height at onset of puberty is the main factor affecting final height.