Jana Kollerová, Martina Klinovská, Juraj Payer
Thyroid hormone resistance syndrome or Refetoff syndrome is an uncommon thyroid function problem. This inherited
condition with reduced intracellular action of thyroid hormones is accompanied by persistent elevation of fT4 and fT3
with inadequately high TSH. Until recently, generalized or partial pituitary tissue resistance to thyroid hormone was
desribed. Today, we know that any abnormality in the chain of processes involving the creation, transport, adequate
deiodination, receptor response to the action of thyroid hormones or histone acetylation, may result in decreased sensitivity
to thyroid hormones. Congenital syndromes with reduced sensitivity to thyroid hormones include thyroid receptor
resistance (with increased fT4 and fT3), impaired transport of thyroid hormones (with elevated T3) and protein
SBP2 deficit (with increased fT4). TSH may be normal or inappropriately elevated to fT4 and fT3 values. Clinically, the
disorder may or may not present as hypo- or hyperthyroidism. Only correct identification of the syndrome allows for
appropriate management.