Myxedema coma: Difference between revisions
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==Background==
==Background==
*[[Hypothyroidism]] + mental status changes/coma + [[hypothermia]] + precipitating stressor<ref>Wall CR. Myxedema coma: diagnosis and treatment. Am Fam Physician. Dec 1 2000;62(11):2485-90.</ref>
*[[Hypothyroidism]] + [[AMS|mental status changes]]/[[coma]] + [[hypothermia]] + precipitating stressor<ref>Wall CR. Myxedema coma: diagnosis and treatment. Am Fam Physician. Dec 1 2000;62(11):2485-90.</ref>
*Majority of the patients > 60yo<ref>Davis PJ, Davis FB. Hypothyroidism in the elderly. Compr Ther. 1984;10:17–23.</ref>  
*Majority of the patients > 60yo<ref>Davis PJ, Davis FB. Hypothyroidism in the elderly. Compr Ther. 1984;10:17–23.</ref>  
*Occurs in 0.1% of patients with hypothyroidism
*Occurs in 0.1% of patients with hypothyroidism
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*[[GI bleed]]
*[[GI bleed]]
*Metabolic abnormalities ([[hypoxia]], [[hypercapnia]], [[hyponatremia]], [[hypoglycemia]])
*Metabolic abnormalities ([[hypoxia]], [[hypercapnia]], [[hyponatremia]], [[hypoglycemia]])
*Medications: [[Beta blockers]], sedatives, opioids, phenothiazine, [[amiodarone]]<ref>Mazonson PD et al. Myxedema coma during long-term amiodarone therapy. Am J Med. 1984;77:751–4.</ref>
*Medications: [[Beta blockers]], [[sedatives]], [[opioids]], [[phenothiazines]], [[amiodarone]]<ref>Mazonson PD et al. Myxedema coma during long-term amiodarone therapy. Am J Med. 1984;77:751–4.</ref>
**Especially medications with CNS depressant effect <ref>Thiessen, M. (2018). Thyroid and Adrenal Disorders. Rosen's Emergency Medicine (9th ed.). Philadelphia, PA: Elsevier/Saunders.</ref>
**Especially medications with CNS depressant effect <ref>Thiessen, M. (2018). Thyroid and Adrenal Disorders. Rosen's Emergency Medicine (9th ed.). Philadelphia, PA: Elsevier/Saunders.</ref>
*Medication non-adherence (thyroid meds)
*Medication non-adherence (thyroid meds)
*[[MI]]
*[[MI]]
*[[Sepsis]]
*[[Sepsis]]
*Trauma
*[[Trauma]]
*[[PE]]
*[[PE]]


==Clinical Features==
==Clinical Features==
===Hypothermia===
===[[Hypothermia]]===
*Temperature <35.5°C (95.9°F).  
*Temperature <35.5°C (95.9°F).  
===Cardiovascular===
===Cardiovascular===
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===Pulmonary===
===Pulmonary===
*Hypoventilation
*Hypoventilation, [[hypercapnia]]
**Early respiratory support with intubation is necessary to prevent respiratory collapse
*[[Hypercapnia]]
**There is often diaphragmatic dysfunction that causes worsening hypoventilation.  The dysfunction is reversed after thyroid hormone administration<ref>Martinez FJ et al. Hypothyroidism. A reversible cause of diaphragmatic dysfunction. Chest. 1989;96:1059–63.</ref>
**There is often diaphragmatic dysfunction that causes worsening hypoventilation.  The dysfunction is reversed after thyroid hormone administration<ref>Martinez FJ et al. Hypothyroidism. A reversible cause of diaphragmatic dysfunction. Chest. 1989;96:1059–63.</ref>
*Hypoxia
**Early respiratory support with intubation may be necessary to prevent respiratory collapse
*[[Hypoxia]]
*[[Pleural Effusion]]
*[[Pleural Effusion]]
*Upper airway obstruction from glottic edema, vocal cord edema, and macroglossia can complicate intubation.
*Upper airway obstruction from glottic edema, vocal cord edema, and macroglossia can complicate intubation.
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===Neurologic===
===Neurologic===
*[[Altered mental status]]/[[Coma]] due to CO2 narcosis
*[[Altered mental status]]/[[Coma]] due to CO2 narcosis
*Coma is very rare
*[[Coma]] is very rare
*Pseudomyotonic "hung up" deep tendon reflexes
*Pseudomyotonic "hung up" deep tendon reflexes
**Particularly Achilles reflex
**Particularly Achilles reflex
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==Evaluation==
==Evaluation==
===Work-Up===
===Work-Up===
*TSH, FT4, FT3
**In primary hypothyroidism TSH will be elevated and T4 and T3 will be low
**If the patient has secondary hypothyroidism (Pituitary dysfunction) the TSH may be low or normal and T4 and T3 will be low
*Chemistry
*Chemistry
**Hyponatremia
**[[Hyponatremia]]
**Hpoglycemia
**[[Hypoglycemia]]
**+/- [[renal failure|Elevated creatinine]]
*CBC
*CBC
**Mild anemia
**Mild [[anemia]], [[leukopenia]]
*TSH, FT4, FT3
*[[Blood cultures]]
*[[Blood cultures]]
*LFTs
*[[LFTs]]
**Elevated
**Elevated transaminases
*[[Rhabdomyolysis|Elevated CPK]]
*Cortisol level  
*Cortisol level  
*VBG/ABG
*[[VBG]]/ABG
**Hypercapnia
**[[Hypercapnia]]
**Hypoxia
**Hypoxia
*Lipid levels
*Lipid levels
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**Ventricular dysrhythmias
**Ventricular dysrhythmias
*Bedside [[cardiac US]] for [[pericardial effusion]]
*Bedside [[cardiac US]] for [[pericardial effusion]]
===Lab Abnormalities===
*Abnormal Thyroid Hormone Levels
**In primary hypothyroidism TSH will be elevated and T4 and T3 will be low
**If the patient has secondary hypothyroidism (Pituitary dysfunction) the TSH may be low or normal and T4 and T3 will be low
*[[Anemia]]
*[[Rhabdomyolysis|Elevated CPK]]
*[[Renal Failure|Elevated creatinine]]
*Elevated transaminases
*[[Hypercapnia]]
*Hyperlipidemia
*[[Hypoglycemia]]
*[[Hyponatremia]]
*[[Hypoxia]]
*Leukopenia
*Respiratory acidosis


==Management==
==Management==
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*In patients who are hyponatremic, be cautious with rapid correction of hyponatremia
*In patients who are hyponatremic, be cautious with rapid correction of hyponatremia
**Consider fluid restriction
**Consider fluid restriction
**Consider hypertonic saline if Na < 120
*Use D5NS if hypoglycemic
*Use D5NS if hypoglycemic


===Hypotension===
===[[Hypotension]]===
*[[Vasopressors]] will be ineffective without concomitant thyroid hormone replacement
*[[Vasopressors]] will be ineffective without concomitant thyroid hormone replacement
===Hormone Replacement===
===Hormone Replacement===
*'''[[Hydrocortisone]]''' 100mg q8hr IV since there is also adrenal insufficiency present
**Alternative: Dexamethasone 2-4mg q12hrs (will not affect cortisol level or ACTH stimulation test)
*'''[[Levothyroxine]] (T4)''' (generally agreed upon first line therapy)
*'''[[Levothyroxine]] (T4)''' (generally agreed upon first line therapy)
**Dose: 100 to 500 mcg (4mcg/kg IV) followed by 75 to 100 mcg administered IV daily until the patient takes oral replacement.<ref>Smallridge RC. Metabolic and anatomic thyroid emergencies: a review. Crit Care Med. 1992;20:276–91</ref>
**Dose: 100 to 500 mcg (4mcg/kg IV) followed by 75 to 100 mcg administered IV daily until the patient takes oral replacement.<ref>Smallridge RC. Metabolic and anatomic thyroid emergencies: a review. Crit Care Med. 1992;20:276–91</ref>
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**More rapid onset but may be harmful in patients with CAD
**More rapid onset but may be harmful in patients with CAD


===Adrenal Insufficiency===
===[[Adrenal Insufficiency]]===
*Hydrocortisone 100 mg IV for possible concomitant adrenal insufficiency  
*[[Hydrocortisone]] 100 mg IV q8h for possible concomitant adrenal insufficiency  
**Alternative: [[dexamethasone]] 2-4mg q12hrs (will not affect cortisol level or ACTH stimulation test)


===Hypothermia===
===[[Hypothermia]]===
*Treat with passive rewarming
*Treat with passive rewarming
*[[Hypothermia]] will also reverse with thyroid hormone administration
*[[Hypothermia]] will also reverse with thyroid hormone administration

Revision as of 16:36, 28 September 2019

Background

  • Hypothyroidism + mental status changes/coma + hypothermia + precipitating stressor[1]
  • Majority of the patients > 60yo[2]
  • Occurs in 0.1% of patients with hypothyroidism
    • Usually occurs after precipitating incident in patient with untreated hypothyroidism [3]
  • Mortality may be as high as 60%[4]
  • Untreated mortality approaches 100% [5]
  • ~50% of cases become evident after admission
  • Severe hypothyroidism may be first time presentation of hypothyroid[6]

Precipitants

Clinical Features

Hypothermia

  • Temperature <35.5°C (95.9°F).

Cardiovascular

Pulmonary

  • Hypoventilation, hypercapnia
    • There is often diaphragmatic dysfunction that causes worsening hypoventilation. The dysfunction is reversed after thyroid hormone administration[9]
    • Early respiratory support with intubation may be necessary to prevent respiratory collapse
  • Hypoxia
  • Pleural Effusion
  • Upper airway obstruction from glottic edema, vocal cord edema, and macroglossia can complicate intubation.

Neurologic

  • Altered mental status/Coma due to CO2 narcosis
  • Coma is very rare
  • Pseudomyotonic "hung up" deep tendon reflexes
    • Particularly Achilles reflex
    • Relaxation phase of DTR twice as long as contraction phase
  • Neuropsychiatric symptoms [10]
    • Depression
    • Psychosis

Differential Diagnosis

Evaluation

Work-Up

Management

Respiratory Support

  • Early mechanical ventilation will prevent respiratory collapse and severe respiratory acidosis.

Fluid Resuscitation

  • Often intravascularly depleted
    • May have underlying illness causing dehydration
  • In patients who are hyponatremic, be cautious with rapid correction of hyponatremia
    • Consider fluid restriction
  • Use D5NS if hypoglycemic

Hypotension

  • Vasopressors will be ineffective without concomitant thyroid hormone replacement

Hormone Replacement

  • Levothyroxine (T4) (generally agreed upon first line therapy)
    • Dose: 100 to 500 mcg (4mcg/kg IV) followed by 75 to 100 mcg administered IV daily until the patient takes oral replacement.[11]
    • Does require extrathyroidal conversion which can be reduced in myxedema but will have a slow steady onset of action
    • Potentially safer in patients with CAD
    • American Thyroid Association recommends treatment with both T4 and T3[12]
  • T3 20mcg IV followed by 2.5-10mcg q8hr
    • Start with 10mcg if elderly or has CAD
    • Does not require extrathyroidal conversion
    • More rapid onset but may be harmful in patients with CAD

Adrenal Insufficiency

  • Hydrocortisone 100 mg IV q8h for possible concomitant adrenal insufficiency
    • Alternative: dexamethasone 2-4mg q12hrs (will not affect cortisol level or ACTH stimulation test)

Hypothermia

  • Treat with passive rewarming
  • Hypothermia will also reverse with thyroid hormone administration
  • Avoid mechanical stimulation
  • Do not actively rewarm:
    • Usually are volume depleted
    • Rapid peripheral vasodilation may induce worsening hypotension

Disposition

  • Admit to ICU

See Also

References

  1. ↑ Wall CR. Myxedema coma: diagnosis and treatment. Am Fam Physician. Dec 1 2000;62(11):2485-90.
  2. ↑ Davis PJ, Davis FB. Hypothyroidism in the elderly. Compr Ther. 1984;10:17–23.
  3. ↑ Thiessen, M. (2018). Thyroid and Adrenal Disorders. Rosen's Emergency Medicine (9th ed.). Philadelphia, PA: Elsevier/Saunders.
  4. ↑ Arlot S et al. Myxoedema coma: response of thyroid hormones with oral and intravenous high-dose L-thyroxine treatment. Intensive Care Med. 1991;17:16–8.
  5. ↑ Thiessen, M. (2018). Thyroid and Adrenal Disorders. Rosen's Emergency Medicine (9th ed.). Philadelphia, PA: Elsevier/Saunders.
  6. ↑ Nicoloff JT et al. A form of decompensated hypothyroidism. Endocrinol Metab Clin North Am. 1993;22:279–90.
  7. ↑ Mazonson PD et al. Myxedema coma during long-term amiodarone therapy. Am J Med. 1984;77:751–4.
  8. ↑ Thiessen, M. (2018). Thyroid and Adrenal Disorders. Rosen's Emergency Medicine (9th ed.). Philadelphia, PA: Elsevier/Saunders.
  9. ↑ Martinez FJ et al. Hypothyroidism. A reversible cause of diaphragmatic dysfunction. Chest. 1989;96:1059–63.
  10. ↑ Thiessen, M. (2018). Thyroid and Adrenal Disorders. Rosen's Emergency Medicine (9th ed.). Philadelphia, PA: Elsevier/Saunders.
  11. ↑ Smallridge RC. Metabolic and anatomic thyroid emergencies: a review. Crit Care Med. 1992;20:276–91
  12. ↑ Jonklaas J, Bianco AC, Bauer AJ, Burman KD, Cappola AR, Celi FS, et al. Guidelines for the treatment of hypothyroidism: prepared by the american thyroid association task force on thyroid hormone replacement. Thyroid. 2014 Dec. 24 (12):1670-751.
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