Unusual course of congenital hypothyroidism and route of the L-thyroxine treatment in a preterm newborn.

Congenital hypothyroidism (CH) is the most common endocrine pathology in neonates. Inappropriate treatment of CH is complicated by irreversible brain damage or low IQ score. Hormone replacement therapy with L-thyroxine (L-T4) is sufficient for a very large proportion of patients. However, during treatment, the patient needs to be carefully monitored for presence of factors which might affect the absorption or bio-availability of the drug as well as its dose. Herein, we report a preterm newborn with CH who presented with gastrointestinal problems mimicking necrotizing enterocolitis. The clinical course was also complicated by cholestasis. The L-T4 replacement treatment was switched from oral route to parenteral. After resolution of the cholestasis, L-T4 treatment was continued successfully by the oral route.