Successful Therapy with L-T4 in a 5 Year-old Boy with Generalized Thyroid Hormone Resistance

Resistance to thyroid hormone (RTH) is a rare dominantly inherited disorder caused by mutations in the thyroid hormone receptor P gene which lead to impaired tissue responsiveness to thyroid hormone (TH). RTH is characterized by elevated free thyroid hormone and unsuppressed thyrotropin (TSH) levels. Two types of the disorder have been recognized: selective pituitary resistance and generalized resistance to TH (GRTH). Triiodothyroacetic acid has been used in patients showing hypermetabolism, and L-T-4 treatment in high doses has been suggested in GRTH if patients have signs of clinical hypothyroidism such as growth retardation and developmental delay. The outcome of long-term treatment of GRTH with L-T-4 has not yet been reported. We report a 5 year-old boy who presented with severe growth retardation, fatigue and speech delay. He had hyperactivity despite feeling tired easily. Elevated TH levels with unsuppressed TSH and delayed bone age were determined by laboratory evaluation and he was diagnosed as GRTH. There was no clinicical evidence of hypermetabolism. We could not demonstrate any mutation in thyroid receptor beta1, beta2 or alpha gene of this patient and his parents. L-T-4 treatment was started at conventional doses (6 mug/kg), and after 3 months of treatment T-4 and TSH levels were suppressed successfully. In 12 months of treatment, no side effects were improved without requirement for high doses of L-T-4

A two-day-old hyperthyroid neonate with thyroid hormone resistance born to a mother with well-controlled Graves’ disease: a case report

<p>Abstract</p> <p>Introduction</p> <p>Resistance to thyroid hormone is a syndrome caused by thyroid hormone receptor β mutations, which are usually inherited in an autosomal-dominant pattern.</p> <p>Case presentation</p> <p>Our patient, a Japanese neonate boy, showed hyperthyroid symptoms at age two days. Although our patient was diagnosed as having resistance to thyroid hormone, his hyperthyroid symptoms continued for two weeks. Therefore, our patient was treated with methimazole and iodine for two weeks from birth, showing no side effects and no symptoms upon treatment. At age 70 days, an R243W mutation in thyroid hormone receptor β was detected in our patient; while absent in his mother, the mutation was present in his father, who never showed any symptoms.</p> <p>Conclusions</p> <p>To the best of our knowledge this is the first case report of a resistance to thyroid hormone in a neonate presenting with hyperthyroid symptoms born to a mother with Graves’ disease and treated with methimazole and iodine. These results suggest that methimazole and iodine may be a good short-term option for treatment.</p