Congenital Hypothyroidism: Long-Term Experience with Early and High Levothyroxine Dosage.

Aim: To assess the management and outcome of the congenital hypothyroidism (CH) patients followed at our institution since the introduction of systemic neonatal screening for CH.

Study Design: The records of 139 CH patients referred to our center between 1978 and 2014 were retrospectively reviewed. Biochemical and imaging data at diagnosis, initial treatment and growth were analyzed.

Results: 111 patients had thyroid dysgenesis (64 ectopy, 46 athyreosis and 1 hypoplasia) and 28 patients had a gland in situ (17 dyshormonogenesis/goiter and 11 normal-sized gland). Levothyroxine treatment was initiated at a median age of 11 days with a mean dose of 11.4 µg/kg/day. Compared to those with ectopy, patients with athyreosis had higher thyroid-stimulating hormone (TSH) and lower thyroxine at diagnosis as well as more delayed bone maturation. Between 1978 and 2014, we observed earlier treatment and earlier TSH normalization. Birth auxology was slightly above the mean of the reference population. Growth at 1 and 6 years and school progression at 11 years were similar to those of the reference population.

Conclusion: Ectopy is the commonest cause of CH. Children with CH treated early with a mean levothyroxine dose of 11.4 µg/kg/day had a median TSH of 3.07 mU/l at 1 month of age and normal growth.