THYROID-SICK EUTHYROID SYNDROME

SUMMARY

1. In significant illness the body does not require T3 and converts T4 to reverse T3 (rT3, inactive compound).

2. Low T4, low T3, low TSH, high rT3 in a hospitalized patient.

3. DDx: secondary/tertiary hypothyroidism.

4. To differentiate sick euthyroid vs. secondary/tertiary hypothyroidism ⟹ order rT3 & image the sella.

5. Do not do TFT in sick patients unless the sickness is due to thyroid storm.

Reference(s)

Wilkinson, I., Furmedge, D. and Sinharay, R. (2017). Oxford handbook of clinical medicine. Oxford: Oxford University Press. Get it on Amazon.
Feather, A., Randall, D. and Waterhouse, M. (2020). Kumar And Clark’s Clinical Medicine. 10th ed. S.L.: Elsevier Health Sciences. Get it on Amazon.
Hannaman, R. A., Bullock, L., Hatchell, C. A., & Yoffe, M. (2016). Internal medicine review core curriculum, 2017-2018. CO Springs, CO: MedStudy.
Therapeutic Guidelines. Melbourne: Therapeutic Guidelines Limited. https://www.tg.org.au [Accessed 2021].