Myxedema Coma or Crisis Workup

Updated: Aug 31, 2020
  • Author: Mohsen S Eledrisi, MD, FACP, FACE; Chief Editor: George T Griffing, MD  more...
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Laboratory Studies

Laboratory studies are important to confirm the diagnosis of myxedema coma. However, if the condition is suspected, treatment should be started immediately without waiting for the results.

  • Thyroid function tests
    • TSH is elevated in most patients, indicating a primary thyroid disorder
    • Free T4 and free T3 levels are low
    • A low or normal TSH level with low levels of free T4 and free T3 may indicate that the disorder is due to pituitary or hypothalamic dysfunction  
  • Assessment of adrenal function should be performed. A random serum cortisol can be obtained; however, the test is only helpful if it’s very low (< 3 mcg/dL) or high (>20 mcg/dL). Since most patients will have serum cortisol levels in between these values, an ACTH stimulation test is usually needed to assess the adrenal function. This test should not delay starting treatment. In contrast to hydrocortisone, which interferes with the cortisol assay, leading to falsely normal serum cortisol, dexamethasone does not interfere with the testing and can be administered immediately and continued until the results of the test become available.
  • Hyponatremia with low serum osmolality
  • Because of decreased renal perfusion, serum creatinine levels are usually elevated
  • Hypoglycemia is common and may also be caused by reduced nutrition, sepsis, or the associated adrenal insufficiency.
  • Complete blood count: leukocytosis may not be seen because of hypothermia. A white blood cell differential may be one of the few clues to the presence of infection.

A diagnostic scoring system for the diagnosis of myxedema coma has been proposed. [28] The scoring system gives points for the following indicators: hypothermia; lethargy, obtundation, stupor, or coma; anorexia, reduced intestinal mobility, or paralytic ileus; bradycardia, electrocardiogram changes, pericardial or pleural effusions, cardiomegaly or hypertension; hyponatremia, hypoglycemia, hypoxemia, hypercapnia or reduced glomerular filtration rate, and the presence of a precipitating cause. This scoring system was based on data derived from a small sample of 21 patients, which may limit its generalizability.

Another diagnostic tool, developed by Chiong et al, uses six variables to screen for myxedema coma, including heart rate, temperature, Glasgow coma scale score, TSH levels, free T4 levels, and precipitating factors. The investigators, whose work utilized 10 study patients and 13 controls, reported the tool’s sensitivity and specificity to be about 80%. [29]


Imaging Studies

Chest radiographs may show signs of cardiomegaly, pericardial effusion, congestive heart failure, or pleural effusion.


Other Tests

Electrocardiography may reveal sinus bradycardia, low-amplitude QRS complexes, a prolonged QT interval, flattened or inverted T waves, or arrhythmias.