TY - JOUR T1 - Challenging diagnosis of resistance to thyroid hormone in a patient with pituitary adenoma JF - BMJ Case Reports JO - BMJ Case Reports DO - 10.1136/bcr-2019-229430 VL - 12 IS - 7 SP - e229430 AU - Nelson Carvalho Cunha AU - Leonor Gomes AU - Margarida Bastos Y1 - 2019/07/01 UR - http://casereports.bmj.com/content/12/7/e229430.abstract N2 - The elevation of thyroid hormone with a normal or elevated thyroid-stimulation hormone (TSH) occurs uncommonly. This set a diagnosis challenge between TSH-secreting pituitary adenoma and resistance to thyroid hormone (RTH). We report a case of a young female patient with palpitations, with elevated thyroid hormone and non-suppressed TSH. TSH receptor antibody was undetectable. Thyroid ultrasound revealed mild heterogeneous goitre, and MRI revealed a microadenoma with 7.5 mm length in pituitary’s left lobe. Pituitary hormones were within normal ranges. The thyrotropin-releasing hormone stimulation test showed normal TSH elevation, consistent with RTH. The genetic test revealed a mutation in heterozygosity in THRB gene (G344R) confirming RTH-beta. No pituitary surgery or thyroidectomy was performed nor were prescribed any antithyroid drugs. Inappropriate secretion of TSH requires a high level of clinical suspicion and the proper laboratory, genetic and radiological studies to conduct a correct diagnosis and prevent unnecessary and potential harmful therapies. ER -