Euthyroid Sick Syndrome

Q: In Euthyroid Sick Syndrome which of the following eventually rises? (select one)

A) TSH

B) Total T3

C) Total T4

D) Free T4 

E) reverse T3 (rT3) 

Answer: E

Word of wisdom is not to check thyroid function test in ICUs as it takes only a few hours for a patient to ‘abnormalize’ thyroid function test under stress but if clinically indicated, a clinician should send a full "Thyroid Function Test” including TSH, Total T3, Total T4, Free T4, and rT3 (reverse T3). There is no absolute trend but the general rule of thumb is as patients get sicker and sicker 

“all fall but reverse rise” 

 

i.e. rT3 (reverse T3) will be elevated. It is usually at the later stages. 

#endocrinology

References:

1. Lee S, Farwell AP. Euthyroid Sick Syndrome. Compr Physiol. 2016 Mar 15;6(2):1071-80. doi: 10.1002/cphy.c150017. PMID: 27065175.

2. Economidou F, Douka E, Tzanela M, Nanas S, Kotanidou A. Thyroid function during critical illness. Hormones (Athens). 2011 Apr-Jun;10(2):117-24. doi: 10.14310/horm.2002.1301. PMID: 21724536.

3. Krysiak R, Kędzia A, Kowalcze K, Okopień B. [Euthyroid sick syndrome: an important clinical problem]. Wiad Lek. 2017;70(2 pt 2):376-385. Polish. PMID: 29059662.