Medications Affecting Thyroid Function

Aka: Medications Affecting Thyroid Function, Drug-Induced Thyroiditis

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II. Causes: Medications associated with Hypothyroidism

  1. Inorganic Iodine
  2. Iodide
  3. Amiodarone
  4. Cyanates
  5. Lithium
  6. Interleukin-2
  7. Interferon
  8. Rifampin
  9. Tyrosine Kinase Inhibitors
  10. Immune Checkpoint Inhibitors
  11. Phenobarbital

III. Causes: Medications associated with Hyperthyroidism

  1. Excess Thyroid Hormone intake
  2. Excess Iodine exposure (Jod-Basedow phenomenon)
    1. Dietary Iodine
    2. Radiocontrast Material (contains Iodine)
    3. Amiodarone (contains 37% Iodine)

IV. Causes: Medications causing Thyroiditis

  1. Amiodarone
    1. Type 1 Amiodarone-induced Thyrotoxicosis
      1. Increased Thyroid Hormone synthesis (pre-existing Goiter)
      2. Treated with antithyroid medications (and Beta Blockers as needed for symptom control)
    2. Type 2 Amiodarone-induced Thyrotoxicosis
      1. Destructive Thyroiditis results in increased T4 and T3 release into circulation
      2. Treated with Glucocorticoids (and Beta Blockers as needed for symptom control)
  2. Denileukin (Ontak)
    1. CD25 cytotoxin used in CTCL, CLL, Psoriasis causes Hyperthyroidism
  3. Interferon-alfa
    1. Autoimmune mechanism causes Thyroiditis with Hypothyroidism or Hyperthyroidism
  4. Interleukin-2
    1. Autoimmune mechanism causes Thyroiditis with Hypothyroidism more often than Hyperthyroidism
  5. Lithium
    1. Autoimmune mechanism causes Thyroiditis with Hypothyroidism more often than Hyperthyroidism
  6. Tyrosine Kinase Inhibitors
    1. Thyroid uptake inhibition results in Hypothyroidism

V. Causes: Medications affecting Thyroid Assays

  1. Decreased TSH (but detectable)
    1. Amphetamines
    2. Bromocriptine
    3. Carbemazepine or Oxcarbemazepine
    4. Dopamine (or Dopamine Agonists)
    5. Levodopa
    6. Metformin
    7. Octreotide (or Somatostatin analogs)
    8. Corticosteroids
      1. Dexamethasone (>0.5 mg/day)
      2. Hydrocortisone (100 mg/day)
  2. Increased TSH (<10 U/L)
    1. Amiodarone
    2. Biotin (Vitamin B7, high dose; hold for 2 days before Thyroid Function Tests)
    3. Iodinated Contrast Media
    4. Metoclopramide >1 mg/kg
    5. Metyrapone
  3. Increased Free T4
    1. Iodine sources
      1. Amiodarone
      2. Iodinated Contrast Media
    2. Thyroxine displacement from Thyroid Binding Globulin
      1. Furosemide (>80 mg IV/day)
      2. Heparin IV
      3. Probenacid
      4. NSAIDs
        1. Diclofenac
        2. Naproxen
        3. Salicylates (>2 g/day)
        4. Salsalate (>1.5 to 3 g/day)
  4. Decreased Free T4
    1. Phenytoin
    2. Carbamazepine or Oxcarbemazepine
    3. Biotin (Vitamin B7, high dose; hold for 2 days before Thyroid Function Tests)
  5. References
    1. Ardabilygazir (2018) Cureus 10(6):e2845 +PMID: 30140596 [PubMed]
    2. Dong (2000) West J Med 172(2):102-6 +PMID: 10693372 [PubMed]
    3. Haugen (2009) Best Pract Res Clin Endocrinol Metab 23(6):793-800 +PMID: 19942154 [PubMed]

VI. References

  1. Barbesino (2010) Thyroid 20(7): 763-70 [PubMed]
  2. Perez Lopez (2011) Endocrinol Nutr 58(2): 94-6 [PubMed]
  3. Sweeney (2014) Am Fam Physician 90(6): 389-96 [PubMed]

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