Resistance to thyroid hormone associated with a novel mutation of the thyroid β receptor gene in a four-year-old female

Resistance to thyroid hormone (RTH) is a rare syndrome of reduced responsiveness to thyroid hormone that is caused by an alteration in the thyroid β receptor gene [1,2]. The incidence of RTH is 1:40,000-50,000 live births and inheritance is autosomal dominant [2,3]. De novo mutation occur approximately 17% of cases, and both males and females are equally affected [2]. RTH is associated with elevated circulating levels of triiodothyronine and thyroxine along with increased levels of thyroid stimulating hormone (TSH) [1,2].In response to TSH secretion thyroid enlargement occurs in RTH [2]. In some situations, thyroid enlargement may result in upper airway compression. Learning disabilities, developmental delay, tachycardia, attention-deficit-hyperactivity disorder, and delayed skeletal maturation are also seen in RTH [1,2]. We report a 4-year old girl with upper airway compression due to RTH caused by a novel mutation in the thyroid β receptor gene. We also detail post-operative management with every-other-day tri-iodothyronine.A four-year old female was found to have thyroid enlargement by her primary care provider. At four years of age, she was referred to a pediatric endocrinologist with a large goiter causing compressive symptoms, including sleep apnea and occasional inspiratory stridor. The child had profound hyperkenesis and difficulty with concentration. There was no family history of RTH.At 4 years of age, the child was at the 40th percentiles for height and weight. The blood pressure was 112/61, and the resting heart rate was 120 beats per minute. A large goiter was present. Ultrasonography revealed a diffusely enlarged gland without extension into the thoracic cavity. The estimated gland volume based on ultrasonography was 150 ml.The total T3 was > 2,000 ng/dL (normal range 80-180 ng/dL); the total T4 was 15.1 ug/dL (normal range 4-12 ug/dL); the free T4 was 1.8 ng/dL (normal 0.7-1.9 ng/dL); the TSH was 60 mU/L (normal range 0.5-6 mU/L). The skeletal age was