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Open access

Ohoud Al Mohareb, Mussa H Al Malki, O Thomas Mueller and Imad Brema

Summary

Resistance to thyroid hormone-beta (RTHbeta) is a rare inherited syndrome characterized by variable reduced tissue responsiveness to the intracellular action of triiodothyronine (T3), the active form of the thyroid hormone. The presentation of RTHbeta is quite variable and mutations in the thyroid hormone receptor beta (THR-B) gene have been detected in up to 90% of patients. The proband was a 34-year-old Jordanian male who presented with intermittent palpitations. His thyroid function tests (TFTs) showed a discordant profile with high free T4 (FT4) at 45.7 pmol/L (normal: 12–22), high free T3 (FT3) at 11.8 pmol/L (normal: 3.1–6.8) and inappropriately normal TSH at 3.19 mIU/L (normal: 0.27–4.2). Work up has confirmed normal alpha subunit of TSH of 0.1 ng/mL (normal <0.5) and pituitary MRI showed no evidence of a pituitary adenoma; however, there was an interesting coincidental finding of partially empty sella. RTHbeta was suspected and genetic testing confirmed a known mutation in the THR-B gene, where a heterozygous A to G base change substitutes valine for methionine at codon 310. Screening the immediate family revealed that the eldest son (5 years old) also has discordant thyroid function profile consistent with RTHbeta and genetic testing confirmed the same M310V mutation that his father harbored. Moreover, the 5-year-old son had hyperactivity, impulsivity and aggressive behavior consistent with attention deficit hyperactivity disorder (ADHD). This case demonstrates an unusual co-existence of RTHbeta and partially empty sella in the same patient which, to our knowledge, has not been reported before.

Learning points:

  • We report the coincidental occurrence of RTHbeta and a partially empty sella in the same patient that has not been previously reported.
  • TFTs should be done in all children who present with symptoms suggestive of ADHD as RTHbeta is a common finding in these children.
  • The management of children with ADHD and RTHbeta could be challenging for both pediatricians and parents and the administration of T3 with close monitoring may be helpful in some cases.
  • Incidental pituitary abnormalities do exist in patients with RTHbeta, although extremely rare, and should be evaluated thoroughly and separately.
Open access

Haruhiro Sato and Yuichiro Tomita

Summary

Resistance to thyroid hormone (RTH), which is primarily caused by mutations in the thyroid hormone (TH) receptor beta (THRB) gene, is dominantly inherited syndrome of variable tissue hyposensitivity to TH. We herein describe a case involving a 22-year-old Japanese man with RTH and atrial fibrillation (AF) complaining of palpitation and general fatigue. Electrocardiography results revealed AF. He exhibited elevated TH levels and an inappropriately normal level of thyroid-stimulating hormone (TSH). Despite being negative for anti-TSH receptor antibody, thyroid-stimulating antibody and anti-thyroperoxidase antibody, the patient was positive for anti-thyroglobulin (Tg) antibody. Genetic analysis of the THRB gene identified a missense mutation, F269L, leading to the diagnosis of RTH. Normal sinus rhythm was achieved after 1 week of oral bisoprolol fumarate (5 mg/day) administration. After 3 years on bisoprolol fumarate, the patient had been doing well with normal sinus rhythm, syndrome of inappropriate secretion of TSH (SITSH) and positive titer of anti-Tg antibody.

Learning points:

  • Atrial fibrillation can occur in patients with RTH.
  • Only a few cases have been reported on the coexistence of RTH and atrial fibrillation.
  • No consensus exists regarding the management of atrial fibrillation in patients with RTH.
  • Administration of bisoprolol fumarate, a beta-blocker, can ameliorate atrial fibrillation in RTH.
Open access

Motoyuki Igata, Kaku Tsuruzoe, Junji Kawashima, Daisuke Kukidome, Tatsuya Kondo, Hiroyuki Motoshima, Seiya Shimoda, Noboru Furukawa, Takeshi Nishikawa, Nobuhiro Miyamura and Eiichi Araki

Summary

Resistance to thyroid hormone (RTH) is a syndrome of reduced tissue responsiveness to thyroid hormones. RTH is majorly caused by mutations in the thyroid hormone receptor beta (THRB) gene. Recent studies indicated a close association of THRB mutations with human cancers, but the role of THRB mutation in carcinogenesis is still unclear. Here, we report a rare case of RTH with a papillary thyroid carcinoma (PTC). A 26-year-old woman was referred to our hospital due to a thyroid tumor and hormonal abnormality. She had elevated serum thyroid hormones and non-suppressed TSH levels. Genetic analysis of THRB identified a missense mutation, P452L, leading to a diagnosis of RTH. Ultrasound-guided fine-needle aspiration biopsy of the tumor and lymph nodes enabled the cytological diagnosis of PTC with lymph node metastases. Total thyroidectomy and neck lymph nodes dissection were performed. Following surgery, thyroxine replacement (≥500 μg) was necessary to avoid the symptoms of hypothyroidism and to maintain her TSH levels within the same range as before the operation. During the follow-up, basal thyroglobulin (Tg) levels were around 6 ng/ml and TSH-stimulated Tg levels were between 12 and 20 ng/ml. Up to present, the patient has had no recurrence of PTC. This indicates that these Tg values are consistent with a biochemical incomplete response or an indeterminate response. There is no consensus regarding the management of thyroid carcinoma in patients with RTH, but aggressive treatments such as total thyroidectomy followed by radioiodine (RAI) and TSH suppression therapy are recommended.

Learning points

  • There are only a few cases reporting the coexistence of RTH and thyroid carcinoma. Moreover, our case would be the first case presenting one with lymph node metastases.
  • Recent studies indicated a close association of THRB mutations with human cancers, but the role of THRB mutation in carcinogenesis is still unclear.
  • When total thyroidectomy is performed in patients with RTH, a large amount of thyroxine is needed to maintain their thyroid function.
  • There is no consensus regarding the management of thyroid carcinoma in patient with RTH, but effective treatments such as total thyroidectomy followed by RAI and TSH suppression therapy are recommended.

Open access

Gemma Xifra, Silvia Mauri, Jordi Gironès, José Ignacio Rodríguez Hermosa, Josep Oriola, Wifredo Ricart and José Manuel Fernández-Real

Summary

Background: Thyroid hormone resistance (RTH) is a rare cause of thyroid dysfunction. High TSH levels, as described in RTH syndrome, are known to be associated with an increased risk of developing thyroid nodules with subsequent growth and malignancy.

Patient findings: In 2006, a 29-year-old Caucasian man presented with a palpable mass in the neck. Increased free thyroxine and triiodothyronine levels were found in the context of unsuppressed TSH levels, despite no signs or symptoms of hyperthyroidism. Ultrasonography revealed a multinodular and enlarged goitre, and fine-needle aspiration cytology revealed suspicious features of malignancy. After excluding pituitary tumour and levothyroxine (l-T4) treatment, the patient was diagnosed with generalized RTH. Screening for all the known mutations in thyroid hormone receptor-β (TR β (THRB)) was negative. Thyroidectomy disclosed five Hürthle adenomas and three hyperplasic nodules. Euthyroidism was achieved after surgery with 6.1 μg/kg per day of l-T4.

Conclusion: RTH may be a risk factor that predisposes to the development of multiple Hürthle cell adenomas. To our knowledge, this is the first case of multiple Hürthle cell adenomas in a patient with RTH.

Learning points

  • High TSH levels, as described in RTH syndrome, are known to be associated with an increased risk of developing thyroid nodules, with subsequent growth and malignancy.
  • The exact role of TR β mutants in thyroid carcinogenesis is still undefined.
  • We report the first case of multiple Hürthle cell adenomas associated with RTH.