ESPE Abstracts

Background: There are two liquid formulations of Levothyroxine currently in use in Italy: one containing ethanol (Tirosint®) and the other ethanol-free (Tifactor®). The aim of our study is to compare the two liquid formulations of Levothyroxine in the first six months of treatment in newborns affected by Congenital Hypothyroidism (CH).

Methods: We retrospectively enrolled 156 patients treated with the ethanol-containing solution (Group A) and 49 treated with the ethanol-free solution (Group B) among patients in follow-up at our Institution. We collected data at diagnosis (gestational age, etiology, TSH, fT4, initial dose/kg) and data at 7-15 days, 1 month, 3 months and 6 months after the diagnosis (TSH, fT4, dose/kg); then, we compared median values in group A vs. group B.

Results: We observed lower TSH values at diagnosis in group B than in group A (P=0.0158), and lower dose/kg/day in group B than in group A at 7-15 days (P=0.0116), at 3 months (P=0.0194), and at 6 months (P=0.0014) after diagnosis in babies born at term. Moreover, fT4 concentration was significantly higher in group B at 3 months (P=0.0223), however being always in the correct range for age (median values 1.58 ng/dL in group A, 1.73 ng/dL in group B). We also calculated the percentage of patients with glands in situ and dysgenesis in both groups: we detected a significantly higher rate of glands in situ in group B (72% vs. 57%). Then, we conducted the same analysis considering only patients with in situ gland: we obtained lower TSH levels at diagnosis in group B compared to group A (P = 0.0238), and dose/kg/day lower in group B than in group A (P = 0.0001) at diagnosis. During follow up, we observed significantly higher fT4 values in group B than in group A at 3 months (P = 0.0056), always in the correct range; also, the dose/kg/day at 7-15 days was significantly lower in group B than in group A (P = 0.0002).

Conclusions: Even though data on more patients and more extended follow-up periods are needed, our study confirms the efficacy of both therapeutic strategies in the treatment of CH. This allows us to personalize therapy depending on each patient's individual needs and on the characteristics of each of the two liquid formulations.