euthyroid sick syndrome; nonthyroidal illness syndrome; low T3 syndrome (ESS)

Etiology

• physical or environmental stress
  • excess cortisol production during acute illness
• systemic illness, 75% of patients with critical illness
• pharmaceutical agents; dopamine, glucocorticoids

Pathology

• diminished peripheral conversion of T4 -> T3
• blunted TSH response to TRH
• circulating inhibitors of thyroid hormone binding

Laboratory

• low to low normal total serum T4
  • very low total serum T4 associated with poor outcomes
• lower total serum T3
• low to low normal serum TSH
• high serum reverse T3
• free thyroxine index (FTI) & free T4 may be low
• serum cortisol may be elevated
• serum TSH is increased in the recovery phase
• allow 6-8 weeks after hospital discharge for followup thyroid function tests

Differential diagnosis

• subclinical hyperthyroidism

Management

• no specific therapy required
• thyroid function studies generally normalize by 8 weeks after recovery from precipitating event
• no further testing of hospitalized patients

More general terms

• thyroid disease

Additional terms

• subclinical hyperthyroidism