The Basics of Euthyroid Sick Syndrome

Euthyroid Sick Syndrome is not a real sickness, but rather a proper terminology used for findings related to the abnormalities found in thyroid hormone functioning even when the thyroid in itself is considered normal. It is also called "Non-thyroidal Illness Syndrome" and it usually occurs without preexisting dysfunction on the endocrine system.[1]

Causes of Euthyroid Sick Syndrome

The causes of Euthyroid Sick Syndrome vary depending on the patient’s case and clinical findings. Acute and chronic conditions such as diabetic ketoacidosis, cardiopulmonary bypass, pneumonia, and anorexia nervosa are just some of the conditions where patients are seen with abnormalities in thyroid functioning when checked under clinical setting.

As shared in a review made by Sattar in 2003, patterns of Euthyroid Sick Syndrome may be classified under four major types[2]:

  1. Low T3 Syndrome – seen in 70 per cent of patients, this is considered the most common abnormality associated in nonthyroidal illnesses. As per clinical observation, the triiodothyronine (T3) hormone quickly drops within 24 hours after the onset of the illness. Doctors would determine the severity of the Euthyroid Sick Syndrome based on the drop level degree.

  2. Low T3 and T4 Syndrome – a drop in both thyroid hormones are exhibited by patients with severe illnesses, most of whom are admitted in Intensive Care. About 30 to 50 per cent of patients may experience this syndrome.

  3. High T4 Syndrome – a rare occurrence, affecting about one per cent of patients. Diseases such as hepatitis and primary biliary cirrhosis may cause a spike in a patient’s thyroxine (T4) hormone level causing this symptom.

  4. Other abnormalities – Chronic heart failure, extensive dermatitis, and sepsis are just some of wide range of other abnormalities and diseases that can be symptoms of Euthyroid Sick Syndrome. Drugs used to treat these illnesses are also viewed as major causes.

Symptoms of Euthyroid Sick Syndrome

A patient may be seen with signs of Euthyroid Sick Syndrome even with no evidence of coexisting thyroid or pituitary gland disease. The underlying causal illness must be addressed in order to also treat the symptoms of this syndrome. Symptoms typically disappear once the primary illness has been treated.

According to an article reviewed by Dr Pramod Kerkar, symptoms of Euthyroid Sick Syndrome mimic those of hypothyroidism.[3] These include weight gain, adrenal fatigue, insomnia, and even depression.

Possible Treatment for Euthyroid Sick Syndrome

Since Euthyroid Sick Syndrome is not an actual illness, it is important to address the cause or the underlying systemic disorder causing the abnormalities in thyroid functioning.

Ganesan and Wadud recommend thyroid hormone replacement therapy coupled with continuous monitoring of thyroid functioning while patient is still admitted to the hospital. In their article shared at the National Center for Biotechnology Information, they advised that constant monitoring is essential as low T3 level is linked to how long a patient stays in hospital care.[4]

[1] Euthyroid Sick Syndrome. Aytug S. (2018 October 8)

[2] Euthyroid Sick Syndrome. Sattar A., Asif N., Dawood M., et al. (2003 June). Journal of Pakistan Medical Association Vol.53 No.6.

[3] What is Euthyroid Sick Syndrome: Causes, Symptoms, Treatment, Prognosis, Pathphysiology, Complications, Epidemiology. Kerkar P.

[4] Euthyroid Sick Syndrome. Ganesan K., Wadud K. (2018 January). National Center for Biotechnology Information.


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