ESPE Abstracts

Thyroid hormone resistance (RTH) is characterized by a decreased sensitivity of target tissues to thyroid hormones due to a defect in the THRα - and THRβ -encoded thyroid hormone receptors (THRs). The clinical manifestations range from no symptoms to simple goiter and hypo- or hyperthyroidism, depending on the receptor subtype distribution in the tissues. Here, we report a case of a thyroid hormone-resistance occurring in a 2- year-old boy carrying a THRβ mutation, and the subsequent manifestation of thyroid hormone resistance in his younger sister after birth. He present with elevated T3 and free T4 levels at 3.14 ng/mL and 3.59 ng/dL, respectively. The TSH level at 3.96 μIU/mL, is inappropriately within the normal range, and thyroid autoantibodies are negative. His height and weight show suboptimal growth, falling around the 5ht percentile. Additionally, there is evidence of tachycardia, with a heart rate of approximately 120 beats per minute. No evidence of pituitary abnormalities was found upon performing a sella MRI. However, neither hyperactivity nor developmental delay was observed. A targeted next-generation sequencing panel identified a heterozygote c.1357C>A (p.Pro453Thr) mutation in the THRβ gene. He is taking a beta-blocker for heart rate control. His younger sister present an increase in T3 and free T4 levels to 1.53 ng/mL and 3.32 ng/dL, respectively, after birth, accompanied by an abnormally elevated TSH of 34.6 μIU/mL. There is a family history of thyroid dysfunction in both the children’s mother and her side of the family. Genetic testing for the THRβ gene was conducted on his younger sister and mother. The younger sister is currently taking T3 supplementation due to a persistent increase in TSH. Patients with RTH exhibit various clinical features. Due to its heterogeneous nature, genetic test for accurate diagnosis is important to provide proper management. Thyroid hormone resistance (RTH) is characterized by a decreased sensitivity of target tissues to thyroid hormones due to a defect in the THRα - and THRβ -encoded thyroid hormone receptors (THRs). The clinical manifestations range from no symptoms to simple goiter and hypo- or hyperthyroidism, depending on the receptor subtype distribution in the tissues. Here, we report a case of a thyroid hormone-resistance occurring in a 2- year-old boy carrying a THRβ mutation, and the subsequent manifestation of thyroid hormone resistance in his younger sister after birth. He present with elevated T3 and free T4 levels at 3.14 ng/mL and 3.59 ng/dL, respectively. The TSH level at 3.96 μIU/mL, is inappropriately within the normal range, and thyroid autoantibodies are negative. His height and weight show suboptimal growth, falling around the 5ht percentile. Additionally, there is evidence of tachycardia, with a heart rate of approximately 120 beats per minute. No evidence of pituitary abnormalities was found upon performing a sella MRI. However, neither hyperactivity nor developmental delay was observed. A targeted next-generation sequencing panel identified a heterozygote c.1357C>A (p.Pro453Thr) mutation in the THRβ gene. He is taking a beta-blocker for heart rate control. His younger sister present an increase in T3 and free T4 levels to 1.53 ng/mL and 3.32 ng/dL, respectively, after birth, accompanied by an abnormally elevated TSH of 34.6 μIU/mL. There is a family history of thyroid dysfunction in both the children’s mother and her side of the family. Genetic testing for the THRβ gene was conducted on his younger sister and mother. The younger sister is currently taking T3 supplementation due to a persistent increase in TSH. Patients with RTH exhibit various clinical features. Due to its heterogeneous nature, genetic test for accurate diagnosis is important to provide proper management.