Thyroid hormone resistance

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Thyroid hormone resistance
Other namesResistance to thyroid hormone
Regulation of thyroid hormone
SpecialtyEndocrinology

Thyroid hormone resistance (also resistance to thyroid hormone (RTH), and sometimes Refetoff syndrome) describes a rare

thyroid stimulating hormone (TSH) level is not suppressed, or not completely suppressed as would be expected. The first report of the condition appeared in 1967.[1] Essentially this is decreased end organ responsiveness to thyroid hormones.[2] A new term "impaired sensitivity to thyroid hormone" has been suggested in March 2014 by Refetoff et al.[3]

Presentation

The syndrome can present with variable

goiter and tachycardia. It has also been linked to some cases of attention deficit hyperactivity disorder (ADHD), although the majority of people with that diagnosis have no thyroid problems.[4]
An association with depression has been proposed.[5]

Causes

Normal thyroid hormone function requires normal thyroid hormone transport across cell membrane, appropriate deiodination, thyroid hormone nuclear receptor, thyroid hormone response elements, co-activators, co-repressors, and normal histone acetylation. Any abnormalities in this chain can result in thyroid hormone resistance and it has not been as well studied as the various forms of insulin resistance.[citation needed]

The most well known cause of the syndrome are

THRB gene) of the thyroid hormone receptor, of which over 100 different mutations have been documented.[6]
Mutations in
MCT8 and SECISBP2 have also been associated with this condition.[7]

Regulation of thyroid hormone secretion

Hypothalamus secretes a hormone called

thyroxine (T4) and triiodothyronine (T3). T4 gets converted to active T3 in peripheral tissues with the help of deiodinase enzymes. T3 negatively feedback on the pituitary and decreases TSH secretion.[citation needed
]

Diagnosis

The characteristic

pituitary disorders). The diagnosis may involve identifying a mutation of the thyroid receptor, which is present in approximately 85% of cases.[8]

Management

Beta blockers, like metoprolol, are sometimes used to help suppress symptoms.[citation needed]

Incidence

Thyroid hormone resistance syndrome is rare, incidence is variously quoted as 1 in 50,000 or 1 in 40,000 live births.[9] More than 1000 individuals have been identified with thyroid hormone resistance, of which 85% had thyroid hormone beta receptor mutation.[7]

References

  1. ^
    PMID 4163616
    .
  2. PMID 20610605
    .
  3. PMID 24847459
    .
  4. PMID 8450877
    .
  5. S2CID 19503692
    .
  6. PMID 23195042
    .
  7. ^
    PMID 17574009
    .
  8. PMID 17534237
    .
  9. PMID 14517508
    .

External links

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