Diferencia entre revisiones de «Myxedema coma»
(Created page with "==Background== * Myxedema: thick, nonpitting edematous changes to skin and soft tissues * occurs in 0.1% of patients with hypothyroid * 80% mortality ==Precipitants== * E...") |
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==Background== | ==Background== | ||
*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> | |||
*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== | ||
* | *[[Sepsis]] (most common precipitant AND mimic) | ||
* | *[[Hypothermia]] (primary environmental) | ||
*[[Adrenal crisis]] | |||
*[[Stroke]] / intracranial pathology | |||
*Drug overdose (opioids, sedatives) | |||
*[[Hypoglycemia]] | |||
*[[Heart failure]] | |||
== | ==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<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]] | |||
*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== | ==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== | ==See Also== | ||
*[[Hypothyroidism]] | |||
*[[Thyroid storm]] | |||
*[[Adrenal insufficiency]] | |||
*[[Hypothermia]] | |||
*[[Hyponatremia]] | |||
==References== | |||
<references/> | |||
*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 | |||
[[Category:Endocrinology]] | |||
[[Category:Critical Care]] | |||
[[Category: | |||
Revisión actual - 09:28 22 mar 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
- Sepsis (most common precipitant AND mimic)
- Hypothermia (primary environmental)
- Adrenal crisis
- Stroke / intracranial pathology
- Drug overdose (opioids, sedatives)
- Hypoglycemia
- Heart failure
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
- 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