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Endocrine Abstracts (2017) 49 EP1200 | DOI: 10.1530/endoabs.49.EP1200

Jerez Hospital, Jerez, Spain.


Introduction: Resistance to thyroid hormone (RTH) is a rare autosomal dominant (AD) condition caused by mutations of the Thyroid Hormone Receptor Beta (TR-β) gene, resulting in generalized tissue resistance to thyroid hormone. Euthyroidism is usually maintained at the expense of increased levels of thyroid hormones and with non-supressed TSH.

Case report: A 61 year-old-woman was evaluated for increased free T4 index: 2.29 ng/dl (normal, 0.9–2.1) and free T3 index: 4.59 pg/ml (normal, 2.57–4.43) and normal TSH levels:3.22 μUI/ml (normal, 0.3–5)). Analysis were repeated and laboratory error was excluded. The patient was asymptomatic. A physical examination detected a moderate diffuse goitre and a normal resting heart rate. Thyroid antibodies were negative. Sex hormone binding globulin and gonadotrophin α-subunit were within the normal range and pituitary magnetic resonance imaging ruled out a pituitary adenoma. Thyroid ultrasound showed a multinodular goitre with micronodules (<6 mm size). Thyroid scintigraphy demonstrated a diffuse goitre with increased technetium uptake. A diagnosis of RTH was suspected. Molecular genetic studies showed a change in exon 10 of the TR-β gene: p.L450F (c.C1633T). Later, our patient’s daughter was also diagnosed of RTH and AD inheritance was demonstrated in family segregation studies.

Conclusions: The rare finding of increased thyroid hormones (T3 and T4) with normal or increased TSH level presents a differential diagnosis between a TSH secreting pituitary adenoma and RTH. Mutational analysis of the TR-β gene enables both definitive diagnosis of RTH and family screening. We present a novel mutation of this gene that has not been previously reported. Although, there have been reported mutations affecting another aminoacid substitution at this position (L450P) in cases of RTH.

Volume 49

19th European Congress of Endocrinology

Lisbon, Portugal
20 May 2017 - 23 May 2017

European Society of Endocrinology 

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