Sick euthyroid syndrome in a patient with multilobar pneumonia

Author: V. Dimov, M.D., Cleveland Clinic

A 57 yo female with PMH of SLE, HTN and depression was transferred from an outside hospital for work-up and treatment of a change in mental status and fever. That admission was preceded by a one-week history of diffuse joint pain, weakness, and fatigue.

On transfer, she was diagnosed with multilobar pneumonia and antibiotic treatment with azithromycin and Zosyn was started. Blood cultures showed gram positive cocci in clusters and vancomycin was added. LP was negative for meningitis.

Home medications
Imdur, Toprol XL, Neurontin 300mg bid, Zoloft, Flexeril, Pepcid

Hospital medications
Nexium, Lopressor, azithromycin, Zosyn, vancomycin, Tylenol, heparin for DVT prophylaxis

Physical examination
Unwell, flushed, oxygen via face mask
132/78-38.2-112, 95% 5L face mask
Lungs: Occasional bibasilar crackles
Heart: Clear S1, S2, no murmurs, gallop, or rubs
Abdomen: Soft, NT, ND, +BS
Extremities: no c/c/e

What happened?
On hospital day 2, thyroid function tests showed low levels of TSH, T4 and T3.


Figure 1. Thyroid function tests (TFTs) in sick euthyroid syndrome.

What is the reason for abnormalities in thyroid function tests in this patient?
Sick euthyroid syndrome

What happened next?
The acute infection was treated successfully, repeated TFTs 5 days later were completely normal and the patient was discharged home with a follow-up with her PCP.

Final diagnosis
Sick euthyroid syndrome

Summary
Sick euthyroid syndrome refers to abnormalities in thyroid function that occur in patients with serious illness not caused by primary thyroid or pituitary dysfunction. The syndrome is very common and may be found in up to 70% of hospitalized patients.

The combination of low TSH, low T3, and low T4 usually occurs in patients with the most severe nonthyroidal illness. During the recovery period, TSH levels return to normal or may even rise transiently before returning to normal.

Thyroid function tests should not be measured on seriously ill patients unless there is a strong suspicion of thyroid dysfunction. Treatment of critically ill patients with sick euthyroid syndrome with thyroid hormone is not recommended.

References
Sick euthyroid syndrome. Postgraduate Medicine Journal, 1999.
Euthyroid Sick Syndrome. eMedicine, 2005.

Created: 08/28/2007
Updated: 09/26/2007