ESPE Abstracts

Introduction: Resistance to thyroid hormones is defined as lack of response of peripheral tissues to triiodothyronine (T3) which is the active form of thyroid hormones. In general (85%) a mutation is detected in the thyroid hormone receptor β (THRB) gene and more rarely, the thyroid hormone receptor α (TRHA) gene.

Case: A 4.7-year-old boy, was admitted to the pediatric endocrinology outpatient clinic of Akdeniz University Hospital with an abnormality in thyroid function tests and mental-motor developmental delay. He was delivered by caesarean section (39 wks, weight: 3.1kg, 25th centile). He had no jaundice in the newborn period and was breastfed initially and supplementary food was begun after 6 months. Additional concerns (at age 2 years), including delayed milestones (sitting at 9 months, standing at 14 months, speech and language at 12 months) and gait disturbance, closure of anterior fontanelle at 2 years of age were noted. He failed to gain height and by the age of 4.7 height was 105.8 cm (Z=-0.3, 37.7 centiles), weight was 18.9 kg (Z=0.4), and head circumference was 56 cm (Z=2.9, 100 centiles). Abnormal thyroid function tests (free T4 0.97 ng/dL [normal range: 0.96-1.77 ng/dL]; TSH 2 mIU/L [NR 0.7-5.9 mIU/L]) and IGF1 (9.92 [normal range: 2.87-27.1]) were detected. Also, Hb was 9.1 g/dL (12-16). There was no iron deficiency. The patient suffered from constipation. With ongoing anaemia and abnormal thyroid function tests, a probable diagnosis of resistance to thyroid hormone (RTH) was thought and genetic analysis was performed and heterozygous c.641C>A (p.Ala214As) mutation in the THRA gene was found. Following the genetic diagnosis of RTHα (age 4.7 years), additional features of the disorder ascertained included, dysmorphic facies (broad face, retrognathia, clynodactilia, flattened nasal bridge, hypertelorism, epicanthus) and there was motor dyspraxia. Skeletal abnormalities included abnormal hip x-ray and femoral epiphyseal dysgenesis.

Conclusion: THRA mutations may be more common than expected. In patients with clinical symptoms of anemia, motor-mental development, and skeletal problems a molecular study of THRA defects is recommended.