Myxedema Coma

13 Mar

What is it?

-Basically, it’s decompensated hypothyroidism

Unfortunately the name is misleading- patients with myxedema coma are rarely edematous or comatose.

-Patients already have a decreased metabolic rate (are vasoconstricted to conserve heat) with relative volume depletion (reduced cardiac output). Then something causes decompensation. This is often times infection, but it can be cold exposure, metabolic abnormalities, about anything.

 

Presenting symptoms:

-90% of cases are elderly females in the winter

Sx of hypothyroidism (weight gain, cold intolerance, constipation, hair loss…)

Hypothermia (often profound-even down to 27 Celsius)

AMS (coma not common- more likely to see lethargy and confusion)

-Respiratory sx (hypoventilation->hypoxia/hypercapnia)

-Cardiovascular sx (hypotension, bradycardia)

 

Exam findings:

-Cold, dry skin

-Delayed recovery phase of DTR’s

-Stigmata of hypothyroidism: Myxedema, swollen lips, periorbital edema, puffy hands/face, thickened nose

 

Labs:

Hyponatremia (in 50% of patients, can be severe)

Leukopenia

Hypoglycemia

-Thyroid studies: Most will have primary hypothyroidism (high TSH low fT4), but can see low TSH with low fT4 in hypothalamic or pituitary dysfunction

 

Management:

– Check TSH/T4 along with your other labs. Also order a cortisol level.

– Get blood cultures and start empiric antibiotics. Infection is the most common etiology.

– Give 100mg IV hydrocortisone as adrenal/pitutary dysfunction can be seen with decompensated hypothyroidism

– Give thyroid hormone afterward. The dosing is highly debated. A loading dose of 200-400 mcg of T4 is frequently given, and some endocrinologists give T3 also as T4 alone needs to be converted to T3 (takes hours/days). Note: if you have a high suspicion for myxedema coma, treat before waiting for lab confirmation

– Treat hypotension principally with fluids patients are almost always intravascularly depleted. BP will correct with thyroid hormone but may take a while- treat BP until T4 can act.

Passive re-warming only. Patients who are re-warmed actively are at higher risk of decompensation.

– Admit to ICU

 

Prognosis:

Mortality is still high in these patients- at least 20-25%

 

Bottom line:

Maintain a high index of suspicion for myxedema coma/hypothyroidism, particularly in an elderly female patient with sx of hypothyroidism with mental status changes.

You can’t diagnose it if it didn’t cross your mind.  

 

Submitted by H. Groth.

 

Sources: Swadron, Stuart P. A New Look at Thyroid Emergencies Part I: Myxedema Coma. Emergency Physicians Monthly. August 5, 2010; Up-To-Date; MD Consult; picture

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