Congenital hypothyroidism treatment in infants: a comparative study between liquid and tablet formulations of...

To compare the effects of liquid and tablet formulations of levothyroxine (L-T4) in 78 newborns with congenital hypothyroidism (CH).

39 patients received liquid L-T4 (group A) and 39 patients received tablets (group B). Thyroid-stimulating hormone (TSH) and free thyroxine (fT4) were measured and L-T4 dose recorded at onset of therapy and during the first year of treatment. Developmental quotient (DQ) was assessed by Griffiths' mental development scales at 12 months of age.

Gestational age, birth weight, screening TSH, etiology and severity of CH, age at onset of therapy and median initial L-T4 dose were similar in both groups. fT4 concentration normalized before 10 days of treatment in all patients. Normalization of TSH concentration was achieved after 7-10 days of therapy in 87% of group A patients and in 82% of group B patients. Group A patients had significantly lower TSH values compared with those of group B at 7-10 days (p = 0.05) and 6-8 months (p = 0.043) of treatment, despite similar L-T4 dose and fT4 concentration. Mean DQ scores were within normal range in all patients.

We confirmed the efficacy and safety of both formulations. The TSH inhibition trend when using liquid L-T4 may be linked to a higher absorption in comparison to the tablets.