Approach Considerations
Thyroid storm diagnosis is based on clinical features, not on laboratory test findings. If the patient's clinical picture is consistent with thyroid storm, do not delay treatment pending laboratory confirmation of thyrotoxicosis.
Laboratory Studies
Results of thyroid studies are usually consistent with hyperthyroidism and are useful only if the patient has not been previously diagnosed.
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Test results may not come back quickly and are usually unhelpful for immediate management.
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Usual findings include elevated triiodothyronine (T3), thyroxine (T4), and free T4 levels; increased T3 resin uptake; suppressed thyroid-stimulating hormone (TSH) levels; and an elevated 24-hour iodine uptake. TSH levels are not suppressed in the rare instances of excess TSH secretion.
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CBC count: CBC count reveals mild leukocytosis, with a shift to the left.
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Liver function tests (LFTs): LFTs commonly reveal nonspecific abnormalities such as elevated levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), creatinine kinase, alkaline phosphatase, and serum bilirubin.
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ABG and urinalysis: Measurement of blood gas and electrolyte levels and urinalysis testing may be performed to assess and monitor short-term management.
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Hypercalcemia may occur from thyrotoxicosis.
Imaging Studies
Chest radiography may reveal cardiac enlargement due to congestive heart failure. Radiography may also reveal pulmonary edema caused by heart failure and/or evidence of pulmonary infection.
Head CT scanning may be necessary to exclude other neurologic conditions if diagnosis is uncertain after the initial stabilization of a patient who presents with altered mental status.
Other Tests
ECG is useful in monitoring for cardiac arrhythmias. Atrial fibrillation is the most common cardiac arrhythmia associated with thyroid storm. Other arrhythmias such as atrial flutter and, less commonly, ventricular tachycardia may also occur.
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Pathophysiologic mechanisms of Graves disease relating thyroid-stimulating immunoglobulins to hyperthyroidism and ophthalmopathy. T4 is levothyroxine. T3 is triiodothyronine.
