Rosen & Barkin's 5-Minute Emergency Medicine Consult (386 page)

• Hypothyroid women require increased exogenous thyroid hormone replacement during pregnancy above baseline
  
• Postpartum thyroiditis occurs in up to 10% of women:
  
  • Usually 3–6 mo postpartum
    
  • Typically resolves without treatment
    

DIAGNOSIS

• Exhaustion
  
• Cold intolerance
  
• Headaches
  
• Diminished hearing
  
• Myalgias and muscle weakness
  
• Menorrhagia
  
• Infertility
  
• Carpal tunnel syndrome
  
• Constipation
  
• Weight gain
  
• Depression, hallucinations, or paranoia
  
• Cognitive impairment
  

• Periorbital edema
  
• Sparse, coarse hair and brittle nails
  
• Absent lateral 1/3 of eyebrows (Queen Anne sign)
  
• Husky or hoarse voice
  
• Goiter
  
• Prolonged relaxation phase of deep tendon reflexes (DTRs)
  
• Yellow, dry, pale, cool, coarse skin
  
• Myxedema (dry, waxy swelling of skin)
  
• Nonpitting edema of hands and feet
  
• Myxedema coma:
  
  • Altered mental status
    
  • Hypotension
    
  • Hypothermia
    
  • Respiratory failure
    
  • Bradycardia
    

• Undiagnosed hypothyroidism in infants has largely been eliminated via universal screening at birth
  
• Hypothyroidism in childhood is usually due to Hashimoto disease.
  
• Children may manifest with retardation of mental developmental, linear growth, and sexual maturation
  

Typical symptoms of hypothyroidism may be confused with changes associated with aging.

Lab confirmation of the diagnosis of hypothyroidism/myxedema coma may not be available in the ED, and therapy should be initiated based on clinical suspicion.

Search for the underlying cause of myxedema coma.

• Thyroid function studies:
  
  • Low total and free thyroxine (T
    ₄
    )
    
  • Low total and free triiodothyronine (T
    ₃
    )
    
  • Thyroid stimulating hormone (TSH):
    
    • Increased in primary hypothyroidism but normal or decreased in central pathology
      
• Anemia
  
• Hyponatremia
  
• Hypoglycemia
  
• Hypoxemia
  
• Hypercapnia
  
• Respiratory acidosis
  
• Elevated lactate dehydrogenase (LDH), creatine kinase (CK), cholesterol, creatinine
  

CXR:

• Enlarged cardiac silhouette due to pericardial effusion
  

ECG:

• Sinus bradycardia, low voltage, PR interval prolongation, bundle branch blocks, QT interval prolongation and nonspecific ST–T-wave changes
  
• May see Osborn wave if profoundly hypothermic
  

• Chronic nephritis
  
• Chronic renal disease
  
• Heart failure
  
• Depression
  
• Hypoalbuminemia
  
• Pernicious anemia
  
• Nephrotic syndrome
  
• Sepsis
  

TREATMENT

• ABCs:
  
  • Intubation and ventilation may be necessary
    
• Cardiac monitor
  
• Blood pressure support
  
• Supplemental oxygen to meet metabolic needs
  
• Correct hypothermia:
  
  • Initiate passive warming measures
    
  • Aggressive rewarming may precipitate hypotension from vasodilation
    

• Mild hypothyroidism:
  
  • Refer for oral thyroid hormone replacement as an outpatient
    
• Myxedema coma:
  
  • Life-threatening condition
    
  • Initiate thyroid hormone replacement therapy if a high index of suspicion:
    
    • Prompt IV replacement improves survival
      
    • Controversy over regimen exists
      
    • Thyroxine (T
      ₄
      ) and triiodothyronine (T
      ₃
      )
      
    • Reassess 4 hr after initial dose
      
    • Use smaller doses of T
      ₄
      and avoid T
      ₃
      in the elderly or patients with cardiac disease to avoid precipitating ischemia
      
  • Hydrocortisone to prevent Addisonian crisis
    
  • Dextrose for hypoglycemia
    
  • IV fluid bolus for hypotension:
    
    • Avoid pressors if possible, may precipitate dysrhythmias
      
    • Response to pressors is poor until thyroid replacement initiated
      
    • Thyroid hormone augments pressors
      
  • Consider hypertonic saline for severe hyponatremia
    
  • Correct the underlying precipitant
    

Thyroid hormone therapy:

• Administer T
  ₄
  , T
  ₃
  , or a combination:
  
  • Combination therapy:
    
    • Thyroxine (T
      ₄
      ): 2 μg/kg (ideal body mass) load IV followed by 10–40 μg IV/PO daily
      
    • PLUS
      
    • Triiodothyronine (T
      ₃
      ): 10 μg load IV followed by 10 μg IV q8–12h until able to tolerate PO T
      ₄
      
  • Thyroxine (T
    ₄
    ): 10–40 μg IV or IM daily
    
  • Triiodothyronine (T
    ₃
    ): 10–20 μg load IV followed by 10 μg IV q4h for 24 hr, then 10 μg IV q6h for 24–48 hr
    

• Hydrocortisone: 100 mg (peds: 4 mg/kg/24h) IV q6–8h
  
• Dextrose: 50–100 mL D
  ₅₀
  (peds: 5 mL/kg of D
  ₁₀
  ) IV
  

FOLLOW-UP

All patients with myxedema coma require ICU admission.

Hypothyroidism is managed in the outpatient setting.

• Primary care providers can generally manage hypothyroidism.
  
• Pregnant patients, elderly patients, and those with ischemic heart disease require special consideration when initiating thyroid hormone replacement.
  

• Patients should be referred to a primary care provider for initiation of oral thyroid hormone replacement therapy.
  
• Severe untreated maternal hypothyroidism can negatively impact fetal brain development and cause obstetrical complications.
  

• Signs and symptoms of hypothyroidism are nonspecific and may be confused with other mental or physical disorders.
  
• Response to treatment for hypothyroidism may take weeks and is best initiated by the primary care physician.
  
• Consider myxedema coma in patients with altered mental status and underlying hypothyroidism.
  
• Myxedema coma has a high mortality rate and requires aggressive treatment. However, avoid parenteral T
  ₃
  in cardiac and elderly patients.
  

• Brent GA, Davies TF. Hypothyroidism and thyroiditis. In: Melmed S, Polonsky KS, Larsen PR, et al.
  Williams Textbook of Endocrinology
  . 12th ed. Philadelphia, PA: Saunders Elsevier; 2011:Chapter 13.
  
• Klubo-Gwiezdzinska J, Wartofsky L. Thyroid emergencies.
  Med Clin North Am
  . 2012;96(2):385–403.
  
• Mathew V, Misgar RA, Ghosh S, et al. Myxedema coma: A new look into an old crisis.
  J Thyroid Res.
  2011;2011:493462.
  
• Vaidya B, Pearce SH. Management of hypothyroidism in adults.
  BMJ.
  2008;337:a801.
  

See Also (Topic, Algorithm, Electronic Media Element)

Hyperthyroidism

CODES