Syndromes of Resistance to Thyroid Hormone: Clinical Aspects

摘要: Resistance to thyroid hormone (RTH) is a rare syndrome caused by molecular defect of the receptor β (TRβ) leading decreased responsiveness target tissues action hormones. Despite specific biochemical presentation, characterized elevated levels in presence detectable concentration TSH, resulting clinical phenotype extremely variable. Early recognition RTH mandatory, since its diagnostic procedures, as well management and follow-up differs from that other forms hyperthyroidism, i.e. TSH-secreting pituitary adenoma, Graves’ disease uni- or multinodular toxic goiter. The increasing awareness existence along with introduction ultrasensitive immunometric TSH assay led duplicate number reported new cases every 5 years (Figure 1). In fact, first case described 1967 (1), more than 700 individuals belonging about 250 unrelated families have been identified up day (2, 3). patients all over world, without apparent geographical ethnic predominance preferential sex distribution. use measurement, rarely associated total T4, neonatal screening for congenital hypothyroidism does not help understand real prevalence RTH, which indirectly estimated be around 1 50,000 live births (4).