What is the role of lab testing in the diagnosis of euthyroid sick syndrome?

Updated: Aug 28, 2020
  • Author: Serhat Aytug, MD; Chief Editor: Romesh Khardori, MD, PhD, FACP  more...
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Typical NTI findings are T4 level within the reference range, low T3 level, slightly reduced or reference range level of TSH, elevated rT3 level, and a free T4 level that is within the reference range or is elevated.

In severe NTI, the findings are low T4, low T3, reduced TSH, elevated rT3, and free T4 that is within the reference range or is diminished.

Recommended tests include the following:

  • Total T4

  • Total T3

  • TSH

  • Free T4

  • rT3

  • Free T3

Refer to specific nonthyroidal diseases for particular alterations in thyroid function test results.

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