Background: Some children with congenital hypothyroidism (CH), have persistent hyperthyrotropinemia despite good compliance with levothyroxine.
Objective: To evaluate combination therapy of liothyronine (cytomel) with levothyroxine in CH with persistent hyperthyrotropinemia.
Patients and methods: Files were reviewed retrospectively. Eight female patients with persistently high levels of TSH and upper normal FT4 levels were given either 6.25 or 12 microg liothyronine and the levothyroxine dose was reduced appropriately. Pre- and post-intervention hormone levels and drug doses were evaluated.
Results: TSH decreased in 8/8 and normalized in 6/8 patients. FT4 and free tri-iodothyronine (FT3) remained normal. The levothyroxine-equivalent dose on the combination was 5.0 +/- 0.3 microg/kg/day in infants and 3.4 +/- 0.4 microg/kg/day in children above 2.5 years. Infants required higher liothyronine doses compared with older children (0.66 +/- 0.01 vs. 0.3 +/- 0.05 microg/kg/day).
Conclusions: Combined therapy can achieve normal TSH levels with normal FT4 and FT3. Further long-term research is required to investigate effects on neurodevelopmental outcome.