Euthyroid Hyperthyroxinemia Workup

Updated: Mar 03, 2023
  • Author: Justyna Bart, MD, PhD; Chief Editor: George T Griffing, MD  more...
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Laboratory Studies

In resolving the cause of an elevated thyroxine (T4) level, consider the following:

  • Obtain a detailed clinical evaluation (ie, history, associated medical conditions, drugs, family history) and pay particular attention to the absence or presence of signs that are suggestive of hyperthyroidism.

  • Measure thyroid-stimulating hormone (TSH) by a third-generation assay showing the lack of suppression, except in hyperemesis gravidarum and severe systemic illness.

  • Measure free T4, especially by equilibrium dialysis (criterion standard). Free T4 is normal except in certain instances, such as when drugs (eg, heparin, propranolol, amiodarone, contrast agents) are being used or when acute psychosis, systemic illness, or hyperemesis gravidarum is present. [23, 36]


Imaging Studies

No imaging studies are required to diagnose this condition.