Introduction: Resistance to thyroid hormone (RTH) is a rare disorder characterized by reduced tissuess responsiveness to thyroid hormones (TH). Usually patients with RTH have not clinical signs except goiter. We describe a 70-years old woman with RTH and autoimmune thyroiditis simultaneously.
Case report: Woman 70-years old was hospitalized in our department on August 2011 with suspicious of Thyrotropinoma because of high levels of TSH and fT4.The patient has atrial fibrillation controlled by the β-blockers since 2006. At that time only TSH was assessed 6.8 mU/l (n 0.44.0) and L-T4 50 μg/day was prescribed. After 3 months TSH decreased to 1.9 mU/l, L-T4 was reduced to 25 μg/day. Such dose of L-T4 she took for 3 years and discontinued by herself. Hormonal assessment after 1 year of discontinuation of L-T4 (June 2011): TSH 9.4 mU/l, fT4 118.4 pmol/l (n 1123), T3 10.0 nmol/l (1.44.0), AbTPO 515 U/l (030). Thyroid US revealed a goiter 50 ml, inhomogeneous, without nodules. There were no any clinical symptoms of thyrotoxicosis except normosystolic atrial fibrillation (on β-blockers). We confirmed high levels of TSH and TH. Pituitary MRI was normal. We supposed that thyrotropinoma has not seen on MRI because of its small size. Methimazole was prescribed (5 mg/d). In 1 month TSH increased to 33.8 mU/l, fT4 decreased to 7.5 pmol/l (919.1) and methimazole was stopped, AbTPO increased to 1000 U/l. Next hospitalization of the patient was on April 2012. There were no signs of thyrotoxicosis, atrial fibrillation continued. The complaints on decreased of memory appeared. Thyroid volume was 52 ml, no nodules. TSH 14.3 mU/l, fT4 52.1 pmol/l (1123), T3 14.7 nmol/l (12.8), thyroglobulin 1.45 ng/ml (050). We did not reveal any metabolic disturbances, SHBG 88.1 nmol/l (n 28112), cholesterol 5 mmol/l (3.35.2). Pituitary MRI with contrast was normal. FNAB of thyroid tissue have been done: picture of autoimmune thyroiditis revealed. The patient discharged from hospital with no any thyroid treatment, only on β-blockers and anticoagulants for atrial fibriilation. The patient is on ours observation now.
Conclusion: In this case, we have two different conditions: RTH and autoimmune thyroiditis. We supposed that patients will be hypothyroid in the future.