Myxedema coma: Difference between revisions

(Major update: IV T4/T3 dosing, stress-dose steroids rationale, precipitants, passive rewarming, avoid sedatives, concurrent adrenal insufficiency workup, references with PMIDs)
(Strip excess bold)
 
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==Background==
==Background==
*'''Extreme, decompensated [[hypothyroidism]]''' with end-organ dysfunction
*Extreme, decompensated [[hypothyroidism]] with end-organ dysfunction
*'''True endocrine emergency''' with mortality '''30-60%''' even with treatment<ref>Ono Y, et al. Clinical characteristics and outcomes of myxedema coma: analysis of a national inpatient database in Japan. ''J Epidemiol''. 2017;27(3):117-122. PMID 28142035</ref>
*'''True endocrine emergency''' with mortality '''30-60%''' even with treatment<ref>Ono Y, et al. Clinical characteristics and outcomes of myxedema coma: analysis of a national inpatient database in Japan. ''J Epidemiol''. 2017;27(3):117-122. PMID 28142035</ref>
*Misnomer: patients are not always comatose and myxedema is not always present
*Misnomer: patients are not always comatose and myxedema is not always present
*Most common in '''elderly women''' with undiagnosed or undertreated hypothyroidism
*Most common in elderly women with undiagnosed or undertreated hypothyroidism
*Precipitants:
*Precipitants:
**'''Infection/[[sepsis]]''' (most common trigger)
**Infection/[[sepsis]] (most common trigger)
**Cold exposure, [[hypothermia]]
**Cold exposure, [[hypothermia]]
**Medication non-compliance with levothyroxine
**Medication non-compliance with levothyroxine
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*'''Classic triad''': altered mental status + hypothermia + precipitating event
*'''Classic triad''': altered mental status + hypothermia + precipitating event
*'''Altered mental status''': confusion, lethargy, obtundation → '''coma'''
*'''Altered mental status''': confusion, lethargy, obtundation → '''coma'''
*'''Hypothermia''' (may be severe, <32C; '''absence of fever despite infection''' is classic)
*Hypothermia (may be severe, <32C; absence of fever despite infection is classic)
*'''Bradycardia''' and '''hypotension''' (refractory to vasopressors until thyroid hormone replaced)
*Bradycardia and hypotension (refractory to vasopressors until thyroid hormone replaced)
*'''Hypoventilation''' with [[hypercapnia]] and [[hypoxia]] (respiratory failure)
*Hypoventilation with [[hypercapnia]] and [[hypoxia]] (respiratory failure)
*'''Hyponatremia''' (due to decreased free water excretion — [[SIADH]]-like)
*Hyponatremia (due to decreased free water excretion — [[SIADH]]-like)
*'''Hypoglycemia''' (concurrent [[adrenal insufficiency]] or hepatic dysfunction)
*Hypoglycemia (concurrent [[adrenal insufficiency]] or hepatic dysfunction)
*'''Non-pitting edema''' (myxedema), periorbital swelling
*Non-pitting edema (myxedema), periorbital swelling
*Delayed deep tendon reflexes (hung-up reflexes)
*Delayed deep tendon reflexes (hung-up reflexes)
*Ileus, urinary retention, [[hypothermia]]
*Ileus, urinary retention, [[hypothermia]]
*'''Pericardial effusion''' (may rarely cause tamponade)
*Pericardial effusion (may rarely cause tamponade)


==Differential Diagnosis==
==Differential Diagnosis==
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==Evaluation==
==Evaluation==
*'''TSH''': markedly elevated in primary hypothyroidism (most common)
*TSH: markedly elevated in primary hypothyroidism (most common)
**May be low/normal in central (pituitary/hypothalamic) hypothyroidism
**May be low/normal in central (pituitary/hypothalamic) hypothyroidism
*'''Free T4''': '''very low or undetectable'''
*Free T4: very low or undetectable
*'''Free T3''': low (but less reliable)
*Free T3: low (but less reliable)
*'''BMP''': [[hyponatremia]] (present in ~50%), [[hypoglycemia]]
*BMP: [[hyponatremia]] (present in ~50%), [[hypoglycemia]]
*'''CBC''': may show anemia, leukopenia
*CBC: may show anemia, leukopenia
*'''ABG/VBG''': respiratory acidosis, hypercapnia, hypoxemia
*ABG/VBG: respiratory acidosis, hypercapnia, hypoxemia
*'''Cortisol level''' ('''before starting steroids''') — rule out concurrent adrenal insufficiency
*Cortisol level (before starting steroids) — rule out concurrent adrenal insufficiency
*'''Lactate''': if concern for sepsis
*Lactate: if concern for sepsis
*'''ECG''': [[bradycardia]], low voltage, prolonged QT, possible J (Osborn) waves
*ECG: [[bradycardia]], low voltage, prolonged QT, possible J (Osborn) waves
*'''CXR''': cardiomegaly (pericardial effusion), pleural effusion
*CXR: cardiomegaly (pericardial effusion), pleural effusion
*'''Infectious workup''': blood/urine cultures, CXR (infection is most common precipitant)
*Infectious workup: blood/urine cultures, CXR (infection is most common precipitant)


==Management==
==Management==
===Immediate===
===Immediate===
*'''Airway management''': intubation for respiratory failure or severe AMS
*'''Airway management''': intubation for respiratory failure or severe AMS
*'''Passive rewarming''' (avoid active external rewarming which can cause vasodilation and cardiovascular collapse)
*Passive rewarming (avoid active external rewarming which can cause vasodilation and cardiovascular collapse)
*'''IV access, cardiac monitoring'''
*IV access, cardiac monitoring
*'''Treat precipitant''' (antibiotics for suspected infection, dextrose for hypoglycemia)
*Treat precipitant (antibiotics for suspected infection, dextrose for hypoglycemia)


===Thyroid Hormone Replacement===
===Thyroid Hormone Replacement===
*'''IV levothyroxine (T4)''' is the mainstay:
*IV levothyroxine (T4) is the mainstay:
**'''Loading dose: 200-400 mcg IV''' (or 4 mcg/kg lean body weight)
**Loading dose: 200-400 mcg IV (or 4 mcg/kg lean body weight)
**Then '''50-100 mcg IV daily'''
**Then 50-100 mcg IV daily
*'''IV liothyronine (T3)''' may be added for severe cases:
*IV liothyronine (T3) may be added for severe cases:
**'''5-20 mcg IV''' loading dose, then '''2.5-10 mcg IV q8h'''
**5-20 mcg IV loading dose, then 2.5-10 mcg IV q8h
**T3 has faster onset of action (~4 hours vs 24 hours for T4)
**T3 has faster onset of action (~4 hours vs 24 hours for T4)
**Use with caution in elderly / cardiac patients (arrhythmia risk)
**Use with caution in elderly / cardiac patients (arrhythmia risk)
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===Stress-Dose Steroids===
===Stress-Dose Steroids===
*'''Hydrocortisone 100 mg IV q8h''' — give BEFORE or concurrent with thyroid hormone<ref>Jonklaas J, et al. Guidelines for the treatment of hypothyroidism. ''Thyroid''. 2014;24(12):1670-1751. PMID 25266247</ref>
*Hydrocortisone 100 mg IV q8h — give BEFORE or concurrent with thyroid hormone<ref>Jonklaas J, et al. Guidelines for the treatment of hypothyroidism. ''Thyroid''. 2014;24(12):1670-1751. PMID 25266247</ref>
*Rationale: thyroid hormone replacement increases cortisol metabolism; if concurrent adrenal insufficiency exists, this can precipitate [[adrenal crisis]]
*Rationale: thyroid hormone replacement increases cortisol metabolism; if concurrent adrenal insufficiency exists, this can precipitate [[adrenal crisis]]
*Discontinue steroids once adrenal insufficiency ruled out
*Discontinue steroids once adrenal insufficiency ruled out


===Supportive Care===
===Supportive Care===
*'''Fluid restriction''' if severe [[hyponatremia]] (dilutional)
*Fluid restriction if severe [[hyponatremia]] (dilutional)
*'''Avoid hypotonic fluids''' (worsens hyponatremia)
*Avoid hypotonic fluids (worsens hyponatremia)
*Cautious IV NS for hypotension
*Cautious IV NS for hypotension
*'''Vasopressors''' may be needed but often refractory until thyroid hormone takes effect
*Vasopressors may be needed but often refractory until thyroid hormone takes effect
*'''Avoid sedatives and opioids''' (impair respiratory drive)
*Avoid sedatives and opioids (impair respiratory drive)
*Electrolyte correction (hyponatremia, hypoglycemia)
*Electrolyte correction (hyponatremia, hypoglycemia)


==Disposition==
==Disposition==
*'''ICU admission for all patients'''
*ICU admission for all patients
*Serial monitoring: TSH, free T4, electrolytes, glucose, cortisol
*Serial monitoring: TSH, free T4, electrolytes, glucose, cortisol
*Improvement in vital signs expected within '''24-48 hours'''
*Improvement in vital signs expected within 24-48 hours
*Mental status may take '''days to weeks''' to normalize
*Mental status may take '''days to weeks''' to normalize
*Long-term oral levothyroxine replacement once stabilized
*Long-term oral levothyroxine replacement once stabilized

Latest revision as of 09:28, 22 March 2026

Background

  • Extreme, decompensated hypothyroidism with end-organ dysfunction
  • True endocrine emergency with mortality 30-60% even with treatment[1]
  • Misnomer: patients are not always comatose and myxedema is not always present
  • Most common in elderly women with undiagnosed or undertreated hypothyroidism
  • Precipitants:
    • Infection/sepsis (most common trigger)
    • Cold exposure, hypothermia
    • Medication non-compliance with levothyroxine
    • Surgery, trauma, MI, stroke
    • Medications: amiodarone, lithium, sedatives, opioids, anesthetics
    • Adrenal crisis (concurrent adrenal insufficiency)

Clinical Features

  • Classic triad: altered mental status + hypothermia + precipitating event
  • Altered mental status: confusion, lethargy, obtundation → coma
  • Hypothermia (may be severe, <32C; absence of fever despite infection is classic)
  • Bradycardia and hypotension (refractory to vasopressors until thyroid hormone replaced)
  • Hypoventilation with hypercapnia and hypoxia (respiratory failure)
  • Hyponatremia (due to decreased free water excretion — SIADH-like)
  • Hypoglycemia (concurrent adrenal insufficiency or hepatic dysfunction)
  • Non-pitting edema (myxedema), periorbital swelling
  • Delayed deep tendon reflexes (hung-up reflexes)
  • Ileus, urinary retention, hypothermia
  • Pericardial effusion (may rarely cause tamponade)

Differential Diagnosis

Evaluation

  • TSH: markedly elevated in primary hypothyroidism (most common)
    • May be low/normal in central (pituitary/hypothalamic) hypothyroidism
  • Free T4: very low or undetectable
  • Free T3: low (but less reliable)
  • BMP: hyponatremia (present in ~50%), hypoglycemia
  • CBC: may show anemia, leukopenia
  • ABG/VBG: respiratory acidosis, hypercapnia, hypoxemia
  • Cortisol level (before starting steroids) — rule out concurrent adrenal insufficiency
  • Lactate: if concern for sepsis
  • ECG: bradycardia, low voltage, prolonged QT, possible J (Osborn) waves
  • CXR: cardiomegaly (pericardial effusion), pleural effusion
  • Infectious workup: blood/urine cultures, CXR (infection is most common precipitant)

Management

Immediate

  • Airway management: intubation for respiratory failure or severe AMS
  • Passive rewarming (avoid active external rewarming which can cause vasodilation and cardiovascular collapse)
  • IV access, cardiac monitoring
  • Treat precipitant (antibiotics for suspected infection, dextrose for hypoglycemia)

Thyroid Hormone Replacement

  • IV levothyroxine (T4) is the mainstay:
    • Loading dose: 200-400 mcg IV (or 4 mcg/kg lean body weight)
    • Then 50-100 mcg IV daily
  • IV liothyronine (T3) may be added for severe cases:
    • 5-20 mcg IV loading dose, then 2.5-10 mcg IV q8h
    • T3 has faster onset of action (~4 hours vs 24 hours for T4)
    • Use with caution in elderly / cardiac patients (arrhythmia risk)
  • Route must be IV — GI absorption unreliable due to ileus and mucosal edema

Stress-Dose Steroids

  • Hydrocortisone 100 mg IV q8h — give BEFORE or concurrent with thyroid hormone[2]
  • Rationale: thyroid hormone replacement increases cortisol metabolism; if concurrent adrenal insufficiency exists, this can precipitate adrenal crisis
  • Discontinue steroids once adrenal insufficiency ruled out

Supportive Care

  • Fluid restriction if severe hyponatremia (dilutional)
  • Avoid hypotonic fluids (worsens hyponatremia)
  • Cautious IV NS for hypotension
  • Vasopressors may be needed but often refractory until thyroid hormone takes effect
  • Avoid sedatives and opioids (impair respiratory drive)
  • Electrolyte correction (hyponatremia, hypoglycemia)

Disposition

  • ICU admission for all patients
  • Serial monitoring: TSH, free T4, electrolytes, glucose, cortisol
  • Improvement in vital signs expected within 24-48 hours
  • Mental status may take days to weeks to normalize
  • Long-term oral levothyroxine replacement once stabilized

See Also

References

  1. ↑ Ono Y, et al. Clinical characteristics and outcomes of myxedema coma: analysis of a national inpatient database in Japan. J Epidemiol. 2017;27(3):117-122. PMID 28142035
  2. ↑ Jonklaas J, et al. Guidelines for the treatment of hypothyroidism. Thyroid. 2014;24(12):1670-1751. PMID 25266247
  • Mathew V, et al. Myxedema coma: a new look into an old crisis. J Thyroid Res. 2011;2011:493462. PMID 22028977
  • Klubo-Gwiezdzinska J, Wartofsky L. Thyroid emergencies. Med Clin North Am. 2012;96(2):385-403. PMID 22443982
  • Wall CR. Myxedema coma: diagnosis and treatment. Am Fam Physician. 2000;62(11):2485-2490. PMID 11130234
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