Endocrine Abstracts

JOINT1634

Thyroid hormone resistance syndrome (RTH) is a rare endocrine disease mainly caused by thyroid hormone receptor (THR) deficiency, characterized by elevated free thyroid hormones (FT3, FT4) and unsuppressed thyroid stimulating hormone (TSH). In this study, we report two cases of RTH in young children, both with developmental disorders. Child 1 was a 4-year-old boy who presented to the clinic with language delay, global developmental delay, mental retardation, and thyroid function showing elevated FT3 and FT4 and normal or elevated TSH. Genetic testing revealed a de novo heterozygous mutation in the thyroid hormone receptors beta (THRB) gene c.1373T>C, resulting in a change in amino acid at position 458 of THRB from valine to alanine (p.Val458Ala) in the form of generalized thyroid hormone resistance (GRTH). Child 2 was a 2-year-old boy who presented to the clinic with abnormal thyroid function, characterized by growth retardation, severe low body weight, and emaciation, accompanied by tachycardia as a symptom of thyrotoxicosis. Genetic testing revealed a de novo heterozygous mutation in the THRB gene c.959G>A, resulting in a change in amino acid 320 of THRB from arginine to histidine (p.Arg320His), which was considered to be a selective pituitary thyroid hormone resistance (PRTH) type. We used β-blockers to control symptoms in child 2 with hyperthyroidism and developed individualized nutritional support programs for two children with growth and developmental disorders. The clinical manifestations of thyroid hormone resistance syndrome are complex, and early genetic testing can help reduce misdiagnosis and underdiagnosis. Its treatment is symptomatic and inappropriate methods such as antithyroid drugs, thyroidectomy and ablation therapy should be avoided.

Keywords: thyroid hormone resistance syndrome;thyroid hormone receptors beta;children;developmental disorders;genetic testing.