Myxedema coma

Background

• Myxedema: thick, nonpitting edematous changes to skin and soft tissues
• occurs in 0.1% of patients with hypothyroid
• 80% mortality

Precipitants

• Exposure to Cold
• Infection (esp pulmonary)
• CHF
• Trauma
• Drugs: phenothiazines, pheobarbitol, narcotics, anesthetics, bdzs, lithium
• Iodides
• CVA
• Hemorrhage (GI)

Diagnosis

• AMS
• unsteady gait
• Skin findings (cool, dry, coarse, pale)
• soft tissues with nonpitting, waxy, dry edema (periorbital edema)
• loss of axillary and pubic hair
• Hypothermia (core temp <37C)
• Cardiovascular alterations (bradycardia)
• Hypoventilation --> respiratory collapse
• abdominal distension
• Delayed DTRs
• Precipitant
• Hypoglycemia
• Hyponatremia

Work-Up

• Chem panel (shows hyponatremia)
• serum osms
• accucheck (may be normal or low)
• CBC
• cultures
• total CK
• LFTS
• LDH
• TSH, FT4, FT3
• cortisol level
• ABG
• ECHO
• CXR
• EKG

DDx

• CHF
• Pulmonary Edema
• hypoventilation syndromes
• hypothermia
• Depression/SI
• hepatic encephalopathy
• shock
• CVA

Treatment

• Intubation and mechanical ventilation if pt has significant respiratory acidosis, hypercapnia, or hypoxia
• IV thyroid replacement
• 500-800 mcg of Levothyroxine then 50-100mcg IV qday
• consider 10-20mcg q12hrs IV of T3 in younger patients with low cardiovascular risk
• Steroid Replacement
• 5-10mg/hr IV hydrocortisone
• treat associated infections
• correct severe hyponatremia and hypoglycemia
• passive external rewarming

Disposition

• Admit to ICU
• get endocrine consult

See Also

Hypothyroidism

Thyroid (General)

Source

Emedicine

Adapted from PANI, Clarke