Liquid formulations of Levothyroxine with ethanol or with parabens for treatment of congenital hypothyroidism: similar TSH and fT4 values in the first 6 months of follow up.

purposeTwo liquid formulations of Levothyroxine (L-T4) are available in Italy: one containing ethanol and one containing parabens. In the literature, few data demonstrate efficacy of the ethanol-free formulation. Our study aims at comparing the efficacy of these formulations in the first six months of treatment in newborns affected by congenital hypothyroidism (CH).

methods236 children diagnosed with CH in our centre between 2011 and 2022 were enrolled according to the L-T4 formulation used: ethanol-containing (group A) or parabens-containing (group B). We collected data at diagnosis (gestational age, TSH, fT4, daily dose/kg, aetiology), at 7-15 days, 1 month, 3 months, and 6 months after diagnosis (TSH, fT4, daily dose/kg).

results164 patients were enrolled in group A and 72 in group B. TSH was lower in group B compared to group A at diagnosis. fT4 was significantly higher in group B at 1 and 3 months, but always in the correct range for age. L-T4 dosage was lower in group B than in group A at 7-15 days, 1 month, and 6 months after diagnosis. Since more patients had gland in situ in group B than in group A (75 vs 57%), we repeated the previous analyses in this subgroup of patients, confirming the results. In both subgroups, the percentages of patients with TSH and fT4 concentrations within normal range during follow-up were not significantly different.

conclusionOur study confirms the efficacy of both therapeutic strategies in the treatment of CH, allowing to individualize therapy depending on the needs of each patient.