Treatment of congenital hypothyroidism: Comparison between L-thyroxine oral solution and tablet formulations up to 3 years of age

Abstract

Objective: Oral solution and tablet formulations of levothyroxine (L-T4) a re both used in the treatment of congenital hypothyroidism (CH). However, few studies and with a limited fo llow-up period have been published comparing these two formulations in children. Design: The aim of this multicenter study was to compare the effectivene ss of L-T4 oral solution (with ethanol as excipient) and tablet formulation in children with CH up to 3 y ears of age. Methods: Children diagnosed with CH between 2006 and 2015 were enrolled and divided into two groups according to the L-T4 formulation used: solution in drops (group D) or table ts (group T). Auxological parameters, thyroid-stimulating hormone (TSH) and free thyroxine (FT4) values and L-T4 dose wer e collected at diagnosis and at 15 days, 1, 3, 6, 12, 24 and 36 months of treatment. The developmental quotient (DQ) at 1 and 3 years of age was evaluated using Griffiths' Scale. Results: In this study, 254 children were enrolled among which 117 were treated with solution and 137 with tablets. Auxological parameters, dose and thyroid function values at dia gnosis, 3, 6, 12, 24, 36 months were not significantly different. TSH at 15 days (P = 0.002) and 1 month (P = 0.009) was significantly reduced in group D. At 2-year follow-u p, median TSH was significantly lower in group T (P = 0.03). No statistical difference was detected between the media n DQ; however, group D showed lower values in the language subsca le at 12 months and in eye-hand coordination at 36 months. Conclusions: Both therapeutic strategies are effective in the treatment of C H. A higher risk of overtreatment in the first months of therapy seems to be associated with oral solution L-T 4; therefore, a different strategy should be considered when starting and adjusting the dose. No negative effects on cog nitive development were observed. The data obtained are encouraging but long-term follow-up is needed.