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[Thyroid hormone resistance syndromes: clinical aspects]
V Vlaeminck-Guillem1, J L Wémeau
1Clinique endocrinologique Marc-Linquette, USNA CHRU de Lille, France.
La Revue De Medecine Interne
|January 15, 2000
Summary
Thyroid hormone resistance syndromes involve target tissue insensitivity to triiodothyronine (T3), often due to genetic defects in the thyroid hormone receptor beta gene. Diagnosis is crucial for appropriate management, with varying treatments based on clinical presentation.
Area of Science:
- Endocrinology
- Genetics
- Molecular Biology
Background:
- Thyroid hormone resistance (TR) syndromes present diverse clinical states, typically autosomal dominant, marked by reduced tissue sensitivity to triiodothyronine (T3).
- These syndromes stem from genetic defects in the thyroid hormone receptor beta (TR beta) gene, affecting T3 binding and action.
- Key biological feature: elevated circulating thyroid hormones with detectable thyroid-stimulating hormone (TSH), necessitating differentiation from pituitary thyreotropic adenoma.
Purpose of the Study:
- To elucidate the clinical and genetic aspects of thyroid hormone resistance syndromes.
- To differentiate TR syndromes from other causes of abnormal TSH levels.
- To guide appropriate therapeutic strategies based on clinical phenotypes.
Main Methods:
- Clinical phenotyping of patients with variable resistance to thyroid hormone.
- Genetic analysis of the thyroid hormone receptor beta (TR beta) gene.
- Biochemical assessment of thyroid hormone levels and TSH.
Main Results:
- Identified genetic anomalies in the TR beta gene as the common cause for diverse clinical presentations of TR.
- Characterized distinct clinical states, ranging from generalized resistance with euthyroidism to pituitary resistance with thyrotoxicosis.
- Established elevated thyroid hormones with detectable TSH as a hallmark, requiring exclusion of pituitary adenoma.
Conclusions:
- Understanding TR mechanisms enhances knowledge of T3 action via its nuclear receptor.
- Investigating transcriptional cofactors is key to explaining phenotypic variability.
- Further research will refine therapeutic approaches for TR syndromes.