euthyroid sick syndrome

  • related: Endocrine

  • aka nonthyroidal illness syndrome (NTIS)

  • demographics: hospitalized and critically ill patients

  • pathogenesis: illness suppress thyrotropin releasing hormone

  • labs

    • suppressed but detectable TSH
    • undetectable TSH is not NTIS
    • Can sometimes have elevated TSH but not > 20 mU/L
    • T4 usually normal
    • T3 lower than normal due to decreased deiodinase activity
    • reverse T3 increases but biologically inactive
    • TBG decreases, lowering total T4 and T3 levels

  • Treatment

    • Do not need to treat with levothyroxine
    • Recheck TSH 6 weeks after illness