Oh my, Amio: LFTs, PFTs, and TFTs Deranged

AM Report Pearls: Amiodarone’s Effects on LFTs, PFTs, and TFTs

  • Many side effects with PO amiodarone are due to tissue accumulation of rx from long-term therapy – vast majority of amio’s side effects are not seen with short-term use of IV amio!
  • The solvents used in the preparation of IV amiodarone can lead to hypotension, seen in ~26% of pts
  • PFT/Pulmonary toxicity is the one responsible for the most deaths associated with amiodarone therapy!
    • Pulmonary toxicity correlates with the total cumulative dose – takes months to years after initiation to develop (but case reports have described more rapid development)
    • Clinical presentation: non-productive cough & dyspnea seen in 50-75% affected individuals and exam with bilateral inspiratory crackles
    • Pathology: Can range from chronic interstitial pneumonitis to organizing pneumonia to frank ARDS to foamy macrophages in air spaces
    • Serial PFTs/DLCO are not usually useful for prediction of pulmonary toxicity from amiodarone
    • Treatment: Cessation of amiodarone! Steroids have mixed utility
  • TFT/Thyroid toxicity is the most common complication of amiodarone therapy – can see both hypothyroidism & hyperthyroidism!
  • LFT/Hepatotoxicity can be seen in ~15-50% of patients on long therapy – these changes usually resolve
    • Patients on chronic amio are recommended to have AST/ALT checked at baseline & q6months
    • Discontinuing amio is recommended if LFTs persistently greater than 2 X ULN
    • Severe liver injury only occurs in 1% of amio patients annually
    • Of note, IV amiodarone can rarely cause AST/ALT to be markedly elevated (10-100 fold) within 1 day of infusion, and this often resolves once the infusion is started – thought to be a different mechanism than chronic amiodarone exposure
    • In general, amio toxicity is a diagnosis of exclusion and you must carefully rule-out other causes!

Josh reminded us of the helpful NIH website called LIVERTOX (livertox.nih.gov) which you can search by drug and will provide you with helpful case reports and readings on mechanism of drug injury!

Enjoy!

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