Final Height in Italian Patients with Congenital Hypothyroidism Detected by Neonatal Screening: An Observational Study Over 20 Years

Final Height in Italian Patients with Congenital Hypothyroidism Detected by Neonatal Screening:An Observational Study Over 20 Years. Background: Linear growth in patients with congenital hypothyroidism (CH) born in 1970s and 1980s is reported normal. Objective and hypotheses: To evaluate whether the earlier diagnosis and the higher L-T4 starting dose lead to an improvement in growth and pubertal outcome over the last two decades. Method: Two-hundred and fifteen patients with permanent CH born in 1980s and 1990s (age at diagnosis 25.1G10.5 days, starting treatment 8.8G2.9 (g/kg per day) were followed up until final height (FH, growth velocity !1 cm/year) was attained. Results: Height at puberty onset K0.1G1.0 SDS, height gain during puberty K0.1G0.8 SDS. Height at puberty onset was significantly higher than target height (TH; P!0.001). The puberty onset was within the normal limits for age in 212 (98.6%) patients. FH (K0.1G1.0 SDS) was not different ascompared to height at puberty onset but higher than TH (K0.8G 1.0 SDS, P!0.001). FH was significantly correlated with TH (r 2Z 0.564, P!0.001) and height at puberty onset (r 2Z0.685, P!0.001), but not with age at diagnosis or the starting L-T4 /kg per day dose. The curve fitting analysis showed that over the two decades the age at diagnosis progressively decreased (r 2Z0.083, P!0.001), while the TH and the starting L-T4 /kg per day progressively increased (r 2Z0.200, P!0.001 and r 2Z0.033, PZ0.007 respectively). FH was not affected by the irthdate, the age at diagnosis, nor the starting L-T4 replacement dose.Conclusion: Age at puberty onset was normal, as well as FH which was significantly higher than TH. The age at diagnosis did not play any role on FH. Despite the large improvement in the screening strategy and the treatment approach FH did not improve in patients born in 1980s and 1990s. The findings of this study are in keeping with the described secular trend in height. The early diagnosis and the treatment strategy do not seem to affect the FH.