Thyroid Hormone Resistance and Pituitary Enlargement After Thyroid Ablation in a Woman on Levothyroxine Treatment

Abstract

We report a patient with inappropriate secretion of thyrotropin (TSH) and a pituitary mass. Although she had been treated for biochemical hyperthyroidism with thyroid surgery and radioiodine ablation, she had never complained of specific symptoms or demonstrated signs of overt thyroid dysfunction. On evaluation, she had increased free thyroxine and TSH levels, normal serum glycoprotein alpha-subunit levels, and a significant TSH over-response to exogenous thyrotropin-releasing hormone stimulation. Magnetic resonance imaging with gadolinium enhancement showed a pituitary enlargement with suprasellar extension. An indium In 111 pentetreotide scan showed an abnormal focus of radionuclide accumulation in the pituitary area. Sequencing of the TRbeta gene showed that the patient was heterozygous for a new single nucleotide substitution resulting in the replacement of the normal arginine with a serine at amino acid 320 (R320S). We review the difficulties encountered in establishing a correct diagnosis in patients with inappropriate secretion of TSH in combination with pituitary enlargement. Due to its possible false-negative results, we do not recommend the use of indium In 111 pentetreotide as a tool in the differential diagnosis of inappropriate secretion of TSH.

Central hyperthyroidism combined with Graves' disease: case series and review of the literature

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Study on Th17/Treg Cells and Cytokines in Hashimoto's Thyroiditis with Different Iodine Nutrition Status

“…Marazuela reported that the proportion of thyroid tissue and PBMC in AITD patients was significantly higher than that in the control group. Treg cells have functional defects, their inhibitory ability is significantly reduced, and they cannot effectively down-regulate the body's immune response to prevent the occurrence of AITD [29].…”

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“…The index case was challenging despite not having an initial proper assessment by taking TSH into consideration (1). The presence of pituitary enlargement is not an unusual phenomenon with GRTH and pituitary hyperplasia has been reported in several animal studies as well as in human autopsy findings and case reports (2,3). However, the co-existence of these two differentials together can often make a diagnostic dilemma leading to inappropriate therapeutic interventions (4,5).…”