ESPE Abstracts

Background: Hypothyroidism is a common problem during childhood generally due to autoimmune thyroid disease. It can also occur in case of severe loss of serum proteins, as well as in the case presented. The most accepted practice in the treatment of hypothyroidism consists in the oral administration of LT₄. Many conditions may affect the absorption of LT₄.

Case presentation: We report an original case of LT₄ malabsorption in a 6-years old child affected by congenital multiple jejunal atresias. He presented TSH 30 μUI/ml (0.6–6.3) and fT₄ 0.71 ng/dl (0.7–1.8), TGAb 34.5 U/ml (0–40) and TPOAb 20.8 U/ml (0–60), so we started LT₄ tablet 25 μg/day (2.5 μg/kg per day). The US showed a normal gland. After 1 month of treatment, TSH was 80 μUI/ml and fT₄ 0.7 ng/dl, consequently the dosage was increased to 25 μg 5 days per week and 50 μg twice (4 μg/kg per day). Although the dosage was high, after one month TSH increased >150 μUI/ml and fT₄ was 0.2 ng/dl. Poor compliance could be ruled out. A severe malabsorption of oral LT₄ was hypothesized. The LT₄ oral solution, available in Italy, has a more rapid absorption than tablets in studies done in adult populations and this characteristics would have been an advantage in our patient, so we decided to switch to the treatment with LT₄ oral solution at the same dosage. After 4–6 months of treatment with LT₄ oral solution the values of TSH and fT₄ were within the normal range.

Conclusion: Short bowel syndrome is the most common cause of intestinal failure in children and causes altered absorption of many drugs. In this case we observed how the TSH value decreased only after the switch from the LT₄ tablets to the LT₄ oral solution. The most important advantage of LT₄ oral solution consists of a faster absorption, which is very crucial in a population of patients having a limited absorption of drugs. We can certainly highlight the implications of the liquid formulation of LT₄, a novel and useful formulation in cases where the absorption of drugs is clearly hindered.