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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

Nicholas Woodhouse, Fatima Bahowairath and Omayma Elshafie

Summary

A 55-year-old female was referred with abnormal thyroid function tests (TFTs); the free thyroxine level (FT4) was undetectable <3.3 pmol/L (normal: 7.9–14.4), while her FT3, TSH and urinary iodine levels were normal. She was clinically euthyroid with a large soft lobulated goitre that had been present for more than thirty years. She received an injection of recombinant human TSH (rhTSH) following which there was a progressive rise of the FT3 and TSH levels to 23 pmol/L and >100 mIU/L respectively at 24 h, The FT4 however remained undetectable throughout. Being on thyroxine 100 µg/day for one month, her FT4 level increased to 15 pmol/L and TSH fell to 0.08 mIU/L. Four years earlier at another hospital, her FT4 level had been low (6.8 pmol/L) with a normal TSH and a raised Tc-99 uptake of 20% (normal<4%). We checked the TFTs and Tc-99 scans in 3 of her children; one was completely normal and 2 had euthyroid with soft lobulated goitres. Their Tc-99 scan uptakes were raised at 17% and 15%, with normal TFTs apart from a low FT4 7.2 pmol/L in the son with the largest thyroid nodule. This is a previously unreported form of dyshormonogenesis in which, with time, patients gradually lose their ability to synthesize thyroxine (T4) but not triiodothyroxine (T3).

Learning points:

  • This is a previously unreported form of dyshormonogenetic goitre.
  • This goitre progressively loses its ability to synthesize T4 but not T3.
  • The inability to synthesize T4 was demonstrated by giving rhTSH.
Open access

Siew Hui Foo and Shahada A H Sobah

Summary

Hypopituitarism is a rare presentation of Burkitt's lymphoma (BL). The purpose of this report is to present a case of BL presenting with panhypopituitarism and to review other case reports of lymphoma presenting with pituitary dysfunction to highlight the distinguishing features of these cases from other benign aetiologies of pituitary dysfunction such as non-functioning pituitary adenomas. We reviewed a total of 11 cases of lymphoma presenting with pituitary dysfunction published from 1998 to 2013 including the present case. The demographics, clinical presentations, laboratory features, radiological findings, histological diagnosis, treatment administered and outcomes were described. Of the total number of patients, 45.5% of the cases had diffuse large B-cell lymphoma while 27.3% had BL. Anterior pituitary dysfunction was more common than posterior pituitary dysfunction at presentation. The other common associated presenting symptoms were painful ophthalmoplegia, cranial nerve palsies and constitutional symptoms. Hypothalamic–pituitary abnormalities were often demonstrated radiologically to be associated with cavernous sinus and/or stalk involvement. All patients who completed immunochemotherapy responded haematologically. Pituitary dysfunction also improved in most cases although the recovery tended to be partial. In conclusion, a high index of suspicion of underlying malignancy, such as lymphoma, should be present in patients presenting with acute pituitary dysfunction associated with painful ophthalmoplegia, rapidly evolving neurological features, radiological features atypical of a pituitary adenoma and constitutional symptoms. An early diagnosis is essential as prompt initiation of definitive therapy will induce disease remission and recovery of pituitary dysfunction.

Learning points

  • Hypopituitarism may be the presenting symptom of lymphoma in the absence of associated overt symptoms or signs of a haematological malignancy resulting in delay in diagnosis and institution of treatment.
  • Pituitary dysfunction due to tumour infiltration has a greater tendency to involve the posterior pituitary and infundibulum resulting in diabetes insipidus and hyperprolactinaemia compared with a non-functioning pituitary adenoma.
  • The common associated symptoms of hypopituitarism due to lymphoma infiltration of the hypothalamic–pituitary system include painful ophthalmoplegia, cranial nerve palsies and constitutional symptoms.
  • Radiological abnormalities of the hypothalamic–pituitary region are usually present and often associated with cavernous sinus or stalk involvement.
  • With early institution of definitive treatment, both haematological response and improvement of pituitary dysfunction are expected although the reversal of hypopituitarism tends to be partial and delayed.
  • A high index of suspicion of underlying malignancy such as lymphoma should be present in patients presenting with acute pituitary dysfunction associated with painful ophthalmoplegia, radiological features atypical of pituitary adenomas and constitutional symptoms to enable early diagnosis and prompt initiation of definitive therapy.