Euthyroid Sick Syndrome

What is Euthyroid Sick Syndrome?

Euthyroid sick syndrome (ESS), also called non-thyroidal illness syndrome, is basically a self protective mechanism of the body, often occurring during a severe illness, or long starvation. It disrupts normal bodily functions, and is characterized by one or more typical hypothyroidism symptoms despite normal levels of thyroid stimulating hormones T3 and T4.

What Causes Euthyroid Sick Syndrome

The rare endocrine condition occurs when a chronic ailment or an insufficient intake of required calories produces stress in the body. Then, along with lowering of the hormone level, the body produces a type of thyroid hormone (reverse T3) so as to lessen the metabolic rate, which in turn decreases the damage brought by stress.

Risk Factors

ESS is more commonly reported in people with the following conditions:

  • Sepsis
  • Diabetic ketoacidosis
  • Thermal injuries
  • Chronic renal failure
  • Cancer
  • Protein deficiency
  • A low carbohydrate diet or disorders in eating suggesting
  • norexia nervosa
  • Fasting
  • Heart failure
  • Pneumonia
  • Cirrhosis

Newborns in intensive care units are also at a risk of getting affected by the condition.

Signs and Symptoms

Euthyroid Sick Syndrome

The Euthyroid Sick Syndrome symptoms share a similarity with hypothyroidism and involve:

  • Fatigue
  • Weight gain
  • Dry skin
  • Depression
  • Anxiety
  • Low concentration
  • Low libido
  • Pain in muscles
  • Hair loss

Euthyroid Sick Diagnosis and Tests

Blood tests are done to determine the level of TSH which may be low, normal or slightly elevated as compared to hypothyroidism in which the TSH level is usually high. These tests also help to detect an elevated serum cortisol levels.

Rarely, abnormal thyroid function test is done with severely ill patients to help in clinical judgment.

Differential Diagnosis:

  • Hashimoto Thyroiditis
  • Hyperthyroidism
  • Hypothyroidism
  • Thyroid Dysfunction
  • Hypopituitarism

Treatment and Management

Since the hormone levels generally become normal with proper treatment of the underlying ailment, there are no special treatment measures for ESS. Some therapies and medicines that may help to improve the symptoms include:

  • Short term specific thyroid medication, such as amiodarone, and corticosteroids
  • Intravenous vitamin therapy or administration of important vitamins and minerals through the veins
  • Message therapy (for pain and stress associated with the syndrome)

The other modes of treatment and management options are supplements to manage adrenaline function and stress, acupuncture, and changes in lifestyle.

Prevalence and Incidence

ESS can affect people irrespective of age and sex. Its incidence rate is about 70% in hospital inpatients and 10% among hospitalized patients with lower TSH.


Recovery is based on the stage of the underlying illness. Most patients recover with successful treatment of the underlying non-thyroidal ailment, but excessively lowered levels of T4, along with an acute sickness is associated with the risk of mortality.

Euthyroid Sick Syndrome ICD-9-CM and ICD-10 Codes

The ICD-9-CM code for the syndrome is 790.94, and the ICD-10 code is E07.8.



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