Hyperthyroidism, Thyroid Storm, and Graves Disease Workup

Updated: Mar 31, 2022
  • Author: Erik D Schraga, MD; Chief Editor: Romesh Khardori, MD, PhD, FACP  more...
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Laboratory Studies

See the list below:

  • Thyroid function studies confirm the diagnosis in the appropriate clinical setting.

    • Elevation of free T4 and low to undetectable TSH levels are diagnostic of thyrotoxicosis; in earlier stages, T3 rise precedes T4 rise.

    • Excessive TSH levels in the setting of elevated free T4 indicate hyperthyroidism of pituitary origin.

    • There is little utility in obtaining total T4 levels, as variations in serum thyroid-binding proteins alter the ability to interpret results.

    • Particularly in thyroid storm, the diagnosis must be made on the basis of the clinical examination as rapid assays are not universally available.

    • Thyroid function studies do not distinguish thyrotoxicosis from thyroid storm; however, several laboratory abnormalities may be encountered in thyroid storm.

  • Hyperglycemia

  • Hepatic function abnormalities

  • Low serum cortisol

  • Leukocytosis

  • Hypokalemia (in thyrotoxic periodic paralysis)


Imaging Studies

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  • Chest radiography may identify congestive heart failure or pulmonary infections, often associated with progression to thyroid storm.

  • Nuclear thyroid scan

    • Diffuse uptake in Graves disease

    • Focal uptake in toxic nodular thyroiditis


Other Tests

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  • Electrocardiogram

    • Sinus tachycardia most common

    • Atrial fibrillation (often in elderly patients)

    • Complete heart block (rare)