Introduction:
In the neck, there is a butterfly-like organ which is known as the thyroid gland. It produces two important hormones, namely T3 (triiodothyronine) and T4 (thyroxin), that regulate different body functions like metabolism, bone growth, brain development, body temperature, and digestion. The pituitary gland, which is positioned at the bottom of the skull, and the hypothalamus regulate the generation of thyroid hormones. The hypothalamus-pituitary complex releases a hormone called thyroid-stimulating hormone (TSH) into the bloodstream, making the thyroid gland release T3 and T4 when there is an imbalance in the bloodstream.
What Is Euthyroid Sick Syndrome?
Euthyroid sick syndrome (ESS) is a condition in which the thyroid hormone T3 (triiodothyronine) circulating in the blood is low without having an actual thyroid disorder. It commonly occurs following severe illness or prolonged periods of starvation. ESS occurs commonly in hospitalized patients admitted to the intensive care unit (ICU).
What Are the Pathophysiology and Epidemiology of Euthyroid Sick Syndrome?
- Pathophysiology of Sick Euthyroid Syndrome:
During acute illness or stress, the body undergoes various hormonal alterations, including changes in the hypothalamus-pituitary-thyroid (HPT) axis. There is a decrease in the active thyroid hormone T3 due to reduced conversion of T4 to T3 and increased conversion of T4 to reverse T3 (rT3). This decrease in T3 levels is often disproportionate to changes in other thyroid hormones. Illness affects the peripheral tissues' ability to use thyroid hormones effectively, leading to reduced cellular uptake and action of thyroid hormones.
- Epidemiology of Sick Euthyroid Syndrome:
Critically seriously ill patients are frequently seen with sick euthyroid syndrome, especially those in intensive care units (ICUs). It can be seen in a variety of acute illnesses, such as sepsis, multiple organ failure, major surgery, trauma, heart failure, and other critical conditions. The syndrome is prevalent in about 20-30% of hospitalized patients, varying depending on the severity and type of illness.
What Is Euthymic and Euthyroidism?
Euthymic is a term used in psychology and psychiatry to describe a normal, balanced, or stable mood state. It refers to a state of emotional and mental equilibrium characterized by a stable mood within the typical range of emotions. In the context of mental health, it often signifies a balanced mood without symptoms of depression or mania.
A condition known as euthyroidism occurs when blood levels of thyroid hormone are below normal ranges, signifying that the thyroid gland is operating normally.
What Are the Other Names of Euthyroid Sick Syndrome?
The Other Names of the Condition Include:
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Sick euthyroid syndrome (SES).
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Non-thyroidal illness syndrome (NTIS).
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Low T3, low T4 syndrome.
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Thyroid homeostasis in anemia, malnutrition, malignancies, and critical illness(TACITUS).
What Are the Changes That Lead to Euthyroid Sick Syndrome?
A lot of research is underway to understand what changes occur in the body for euthyroid sick syndrome to occur. Some scientific studies claim there is less peripheral conversion of the hormone T4 (thyroxine) to T3 (triiodothyronine). Also, there is a decrease in the clearance of reverse T3 that T4 has generated. Cytokines are also thought to affect the development of ESS. Cytokines are special substances secreted by the cells of the immune system that act on other cells of the body.
How Common Is Euthyroid Sick Syndrome?
ESS can affect people of any age or sex. It can occur in about 70 percent of hospitalized patients and 10 percent of hospitalized patients with low levels of thyroid-stimulating hormone (TSH). Newborns admitted to intensive care units (ICU) are at an increased risk of getting affected by euthyroid sick syndrome (ESS).
What Are the Causes of Euthyroid Sick Syndrome?
Chronic (long-term) illnesses have more chances of having Euthyroid Sick Syndrome, who have been hospitalized for critical conditions or in people with insufficient calorie intake, causing stress on the body. The euthyroid sick syndrome causes a decrease in metabolism, which in turn decreases the effects of stress on the body.
The Following Are the Causes of Euthyroid Sick Syndrome, Which Include:
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Stress.
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Trauma.
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Starvation.
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Sepsis.
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Major surgeries.
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Pneumonia (an air sac infection in the lung that gets filled with fluid or pus).
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Myocardial infarction (MI), or heart attack, is a condition in which blocks in blood vessels lead to blood supply loss, causing the death of the heart muscles.
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Hypothermia (a condition where the body temperature is lower than the normal temperature).
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Cirrhosis (a liver disease that causes scarring of liver tissue and liver failure).
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Anorexia nervosa (an eating disorder with conscious low food intake to maintain a thin body structure).
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Renal failure (where the kidney reaches a state of advanced functional loss).
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Congestive cardiac failure is a heart disease that affects the pumping of the heart, causing symptoms like breathlessness.
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Diabetic ketoacidosis is a complication of diabetes that produces a large amount of ketones in the blood.
What Are the Symptoms of Euthyroid Sick Syndrome?
The symptoms of euthyroid sick syndrome mimic those of hypothyroidism (a condition in which there is decreased production of thyroid hormones).
The following symptoms are noted, which include:
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Excess fatigue or tiredness.
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Weight gain.
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Dry skin.
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Increased anxiety.
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Depression.
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Mood changes.
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Insomnia or disturbed sleep.
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Adrenal fatigue (a group of nonspecific symptoms like body pains, tiredness, nervousness, digestive issues, and sleep disturbances).
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Hair loss.
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Loss of sex drive.
What Are the Complications of Euthyroid Sick Syndrome?
The euthyroid sickness syndrome often gets misdiagnosed as hypothyroidism due to low levels of T3 and high levels of TSH (thyroid-stimulating hormone). There are no noted complications for ESS; Nonetheless, in order to avoid further disorders and consequences, the underlying causes of the sickness must be identified and addressed.
How Is Euthyroid Sick Syndrome Diagnosed?
One of the best diagnoses of this syndrome is blood tests. The affected patients can have slightly high, normal, or low levels of TSH (thyroid-stimulating hormone) based on the intensity of the illness. Free T3 (triiodothyronine) levels are less than normal; in extreme cases, free T4 (thyroxine) levels can also be less than normal. ESS is often associated with TACITUS syndrome these patients may also have increased levels of prolactin, cortisol, and growth hormone.
How Is Euthyroid Sick Syndrome Treated?
Treatment planning for euthyroid sick syndrome is done by physicians or endocrinologists (doctors who specialize in treating disorders of the hormone-secreting endocrine glands). Thyroid hormone replacement is not indicated for most patients. Treatment involves identifying the underlying cause or reason for illness and treating it. Special supplements can be recommended for conditions like stress and other symptomatic conditions.
Lifestyle modifications, administration of intravenous vitamins, and acupuncture (a form of ancient Massage therapy and Chinese medicine, which involves inserting tiny needles into the body to cure certain ailments, have been shown to benefit ESS sufferers.
What Is the Outlook for Euthyroid Sick Syndrome?
Most patients with euthyroid sick syndrome recover well upon successful treatment of the underlying condition causing the illness. However, patients with acute sickness and excessively low levels of T4 are at increased mortality (death) risk.
Conclusion:
Euthyroid sick syndrome (ESS) is a condition that affects patients admitted to critical care units for acute or chronic (long-standing) illnesses. Blood tests show abnormal readings of the thyroid hormone levels despite having no thyroid illness. Thyroid hormone replacement is generally not required. However, thyroid medications may be advised for managing severe cases. The condition is reversible with successful treatment of the underlying cause.
