The term ” euthyroid sick syndrome” describes a condition characterized by serum thyroid hormone changes and thyroid stimulating hormone (TSH) levels that are not caused by intrinsic thyroid function abnormalities. As one of the thyroid diseases, this syndrome is also known as a nonthyroidal illness syndrome.
The euthyroid sick syndrome occurs most frequently in acutely ill infants or children who are admitted to intensive care units. The euthyroid sick syndrome might manifest in a person who is malnourished or suffering from any acute or chronic ailment such as a serious car accident injury, HIV infection or an autoimmune condition.
Euthyroid illness or non-thyroid health syndrome is an abnormal thyroid functioning diagnosis performed in intensive care during acute disease. It is not an actual disorder, but transient changes in the hypothalamic-pituitary-thyroid axis that occur in approximately 75 percent of hospital patients.
These symptoms frequently occur among patients suffering from severe critical health conditions and deprived of calories or during (or after) major surgery. The most prevalent hormone patterns are low T3 and free t3 levels and normal levels of T4 and TSH.
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Types of the euthyroid syndrome normal thyroid function
There are three types of euthyroid syndrome:
- low T4 syndrome
- low T3-low T4 syndrome
- high free T4 syndrome, and other abnormalities.
Most people with euthyroid illness have low levels of T3 in their blood, which affects almost 72% of hospital patients. In reverse euthyroid syndrome, the level of thymic acid is higher, but not in kidney failure. Most of the time, low activity in type I Iodothyronine 5-MONODEiodin causes RT3 to go up. The T4 syndrome shows up in very sick people and in the intensive care unit.
Symptoms of the euthyroid sick syndrome
The typical symptoms include aches and pains, a sluggishness, bloated limbs and face, bloated skin, constipation, bradycardia, and intolerance to cold temperatures. When diagnosing epilepsy, it is vital to determine both the TSH and thyroxine levels.
A normal serum thyroid stimulating hormone levels in critically unwell individuals, despite low T3 and T4 levels, is the defining characteristic of the euthyroid sick syndrome.
Most medical professionals agree that the changes in thyroid function are an “adaptive reaction,” and as a result, they do not recommend treating the condition with thyroid hormone. On the other hand, some believe these alterations are “maladaptive” in particular contexts and that treating patients with thyroid hormones could help ease the situation. Treatment with liothyronine (T3) is crucial for local thyroid hormone metabolism.
Is euthyroidism a problem?
Patients who are severely unwell, lacking nourishment, or have recently undergone major surgery are more likely to have these conditions.
Is there another illness or condition that has some of these same symptoms?
Patients who suffer from central (hypopituitary) hypothyroidism have low blood T4, free T4, and “inappropriately normal” serum TSH levels, which are the same results as patients who suffer from the euthyroid sick syndrome.
Some clinical aspects of acute sickness, such as a lowered body temperature, bradycardia, hypotension, hypoventilation, hypotonia, and impaired mental status, overlap with the symptoms and signs of hypothyroidism. In most cases, laboratory tests can straightforwardly differentiate between primary hypothyroidism and euthyroid sick syndrome.
While patients with euthyroid sick syndrome may have normal or low thyroid hormone levels, patients with primary hypothyroidism have high serum TSH levels. Patients with the sick-euthyroid syndrome may have normal or low serum TSH levels.
Patients with both primary hypothyroidism and sick-euthyroid syndrome have a chance of having lower serum TSH levels. Still, these levels are unlikely to be within the normal range. Patients with this combination of conditions are more likely to have TSH levels outside the normal range. hypothalamic pituitary thyroid axis
What factors led to the onset of this ailment at this particular time?
People can develop sick-euthyroid syndrome due to hunger, trauma, surgery, or severe acute or chronic sickness. In general, genetic or seasonal risk factors predispose someone to have the condition.
A decreased TRH production and TSH secretion can be attributed to starvation and acute sickness. Dopamine and glucocorticoids are two examples of medications frequently used to treat individuals suffering from critical illnesses and can also inhibit TSH secretion. The initial drop in serum levels of thyroid hormone T3 is due to a combination of factors, including decreased production of T3 by the thyroid gland and decreased conversion of T4 to T3 outside of the thyroid gland.
A further consequence of severe acute sickness is a reduction in the T4 produced by the thyroid gland. Decreasing thyroid hormone binding proteins are also the cause of decreased total T4 and total T3 levels (thyroxine-binding globulin [TBG], transthyretin, and albumin). (It seems that a drop in TBG is an example of “acute phase response.”) It would suggest that circulating inhibitors of T4 and T3 binding to their respective proteins are also a contributing factor in low serum total T4 and T3 levels. Certain medications, such as furosemide and salicylate, are used to treat patients and are examples of inhibitors. Another example of an inhibitor is non-esterified fatty acids, created when a patient has the euthyroid sick syndrome.
Both the patient’s medical history and their physical examination can assist in differentiating between this nonthyroidal illness syndrome and genuine hypothyroidism. Children who have been properly diagnosed with hypothyroidism and are on thyroid hormone replacement usually have a history of the condition. In hypothyroidism cases that have not been diagnosed, there may be clues in most patients’ records or the physical examination.
Because autoimmune thyroiditis is the leading cause of acquired hypothyroidism in children, a family history of an autoimmune thyroid illness (such as Hashimoto’s or Graves’ disease) may be present. This is because this thyroiditis is the most prevalent cause of acquired hypothyroidism in children.
The patient’s medical history may shed light on possible causes of hypothyroidism, such as radiation treatment for head and neck malignancies or excessive iodine consumption. A goiter found on the neck exam is evidence of underlying thyroid disease, and a scar on the neck may indicate that the thyroid has been removed in the past.
Acute sickness shares many symptoms with hypothyroidism, including a low body temperature, bradycardia, or hypotension.
What is the best way to treat euthyroid sick syndrome?
The acute illness at the root of the euthyroid sick syndrome should be diagnosed and treated as a top priority. Most experts think that the changes in thyroid hormone and TSH in this thyroid disease are an “adaptive response,” so they do not recommend treatment with thyroid hormone.
However, some think these changes are “maladaptive” and could be helped by treatment with thyroid hormones. Thyroid function tests should be implemented first to identify and evaluate the disease severity. While the patient is in the hospital, thyroid function should be periodically monitored, and then here is a summary of the evidence for treatment in specific clinical situations:
Hypothyroxinemia in preterm babies: Serum T4 levels are lower in preterm babies, and the amount of drop is related to gestational age and birth weight. Clinical trials that used either l-T3 or l-T4 treatment did not find any differences in the measured outcomes, such as the amount of oxygen breathed in, the length of mechanical ventilation, the amount of fluid taken in through the gut, weight gain, CNS ischemia or bleeding, or death.
A review found that there isn’t enough evidence to say whether or not giving preterm babies with hypothyroxinemia thyroid hormone improves morbidity, death, or neurodevelopmental outcome.
– Children with acute illness: Children with acute illness/prolonged critical illness have lower serum T3 and T4 levels and higher rT3 levels, but their TSH levels are normal. Randomized controlled trials (RCTs) have given active thyroid hormone to children in intensive care units who are very sick (ICU). Adults in an ICU who were given l-T4 and burn patients who were given l-T3 in RCTs did not get better.
– Cardiac surgery: When a child has cardiac surgery, their total and free T3 levels drop. By 12 to 48 hours after the surgery, their free T3 levels have dropped as much as 80% from what they were before the surgery
Several studies have found benefits in one or more outcome measures, such as an improved cardiac index, a shorter time to extubation, a more rapid negative fluid balance, an improvement in a measure for critically ill patients (the therapeutic intervention scoring system or TISS), or a trend toward a shorter hospital stay.
Studies on children with CRI show that their total and free T3 and total and free T4 serum levels are low, but their serum TSH levels are usually normal. Either euthyroid sick syndrome or central hypothyroidism could cause these changes. In most cases, rT3 levels in the blood are normal because rT3 levels are high, thyroid dysfunction.
Glucocorticoids and other drugs often used to treat people after a kidney transplant (due to chronic renal failure) lower serum thyroid hormone levels. So, the changes in thyroid function tests seen in people with CRI may have more to do with the euthyroid sick syndrome than with CRI itself. Treatment with T4 or T3 for adults with acute renal failure has not been shown to help in any study.
A euthyroid sick syndrome is usually caused by a short-term illness that lasts a few days or weeks. As was said about the common symptoms of the euthyroid sick syndrome, most people with euthyroid ill syndrome seem to have changes in thyroid function that are “adaptive” and don’t get better with thyroid hormone treatment. Especially if they get only levothyroxine.
There seem to be exceptional cases, such as hypothyroxinemia in preterm infants born before 27 weeks and some infants having heart surgery, where RCTs show that thyroid hormone treatment is helpful. Experts agree that the treatment is not the standard of care.