Certainly, hearing the name euthyroid sick syndrome for the first time will immediately help us know that it could be a particular sign associated with thyroid sickness, that is what so many people would describe it to be based on the name but, could that be the true meaning, we will surely find out briefly.
The euthyroid sick syndrome is also known as nonthyroidal illness syndrome, this refers to the noticeable changes seen in the thyroid function during the test administered in intensive extensive care, although not a true syndrome, it represents a significant alteration in the hypothalamic-pituitary-thyroid axis in a significant amount of hospitalized patient. The condition appears in patients who have a significant level of critical illness, and those who are deprived of calories, it also comes as an after-effect of some major surgeries.
Different diagnosis of euthyroid sick syndrome are;
- Hashimoto thyroiditis or hypothyroidism.
- Hyperthyroidism or thyrotoxicosis.
- Thyroid dysfunction.
Euthyroid sick syndrome is caused by different factors, examples are pneumonia, sepsis, stress, starvation, anorexia nervosa, and traumatic history, for instance, cardiopulmonary bypass, hip fracture, malignancies, organ transplant, renal failure, congestive cardiac failure and to add covid-19 to the list would not be far-fetched.
Decreased triiodothyronine (T3) levels are very common and the most common of the disorder, those who have a more severe or prolonged illness as well have decreased thyroxine (T4) levels, serum reverse T3 is increased. Thyroid stimulating hormone (TSH) levels may be low or normal, and during the phase of syndrome revovery, it could be slightly elevated. In actual sense, we have patients that are actually euthyroid, but based on the underlying acute ot chronic condition, their symptoms may overlap with the case of severe hypothyroidism such as; hypothermia, hypotension, lethargy, hypoventilation or coma.
Euthyroid sick syndrome is caused by an increased circulating level of cytokines and other inflammation mediators resulting from a case of underlying nonthyroidal illness. The signs and symptoms of euthyroid sick syndrome differs from one person to another, decreased level of thyroid hormone include; constipation, infertility, depression, bradycardia, joint and muscle pain, weakness and fatigue, puffy face, cold intolerance, infertility, irregular menstrual flow in the female gender, constipation.
Starvation and acute illness leads to a diminished level of TRH production and the secretion of TSH. Some form of drugs used in the treatment of patients who have acute illness, which includes glucocorticoids and dopamine also exhibit the secretion of TSH. The initial process of T3 serum decrease is the result of having a decreased production of T3 by the thyroid gland as well as the decreased extra-thyroidal conversion of T4 to T3. An increased function of the inactivating type 3 deiodinase (D3) leads to the increased conversion of T4 to reverse T3.
Serious acute illness will futher lead to decreased production of T4 by the thyroid gland. The decreased total levels of T4 and T3 are also a result of decreased thyroid hormone binding proteins. Examples of inhibitors, are non-esterified fatty acids produced with sick-euthyroid syndrome and drugs used in the treatment of patients including salicylate and furosemide.
Treating euthyroid sick syndrome is possible through the treatment of the underlying disease, lots of seriously ill patients have low levels of thyroid hormones but they are not clinically hypothyroid and they do not neccessaraily require thyroid hormone supplementation. Preventing hypothyroidism depends greatly on; if the patient is treated or not treated, with the rapid treatment of thyroid hormone, the hormonal level will return to normal, if on the other hand, the underlying condition is not treated and T4 level reduces below 3 mcg/dL, then euthyroid sick syndrome could be really fatal.
Complications of euthyroid sick syndrome is also highly possible and that is dependent on the organ systems involved and the underlying diseases, but the general complications of hypothyroidism as associated with euthyroid sick syndrome are; consudion, apathy, heart failure, hypothermia, psychosis and bradycardia.
It is important for patients to be notified of the abnormal thyroid test findings and gets advised accordingly to follow up with their physician to help them first of all, recover from their illness and then later reseting their thyroid levels when they have completely recovered from the acute illness. If anything is to be done on thyroid hormone, the recommended timing is usually after six weeks of hospitalization. When a patient continues to show symptom of abnormal thyroid hormone levels even after the initial medical problem has been solved, then there would be a further work-up of the thyroid function that is warranted to clarify and recognize any purely thyroid related issue that requires special evaluation and appropriate treatment.