Sick euthyroid syndrome in a patient with multilobar pneumonia

Author: V. Dimov, M.D.
Reviewer: S. Randhawa, M.D.

A 57-year-old female with a past medical history (PMH) of SLE, hypertension (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 (piperacillin and tazobactam injection) was started. Blood cultures showed gram positive cocci in clusters and vancomycin was added. LP was negative for meningitis.

Home medications

Imdur (isosorbide mononitrate), Toprol XL (metoprolol succinate), Neurontin (gabapentin) 300mg bid, Zoloft (sertraline),cyclobenzaprine (Flexeril), famotidine (Pepcid).

Hospital medications

Nexium (esomeprazole),metoprolol (Lopressor), azithromycin, Zosyn (piperacillin and tazobactam injection), vancomycin, Tylenol (acetaminophen), 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 (click to enlarge the images).

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.


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.


Sick euthyroid syndrome. Postgraduate Medicine Journal, 1999.
Euthyroid Sick Syndrome. eMedicine, 2005.
Approach to a low TSH level: Patience is a virtue — Cleveland Clinic Journal of Medicine, 2010

Published: 08/28/2007
Updated: 09/26/2010


  1. This is very interesting. Alot of patients will get thyroid panels on admission when they are very ill and without known thyroid disease. I would be interested to see if treatment is started without considering this syndrome. What effect would that have on a patient without thyroid disease?

  2. It's unnecessary treatment with potential to harm. You should always consider sick euthyroid syndrome in all hospitalized patients with abnormal TFTs.