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Congenital adrenal hyperplasia
Primary adrenal insufficiency
Adrenal cortical carcinoma
Thyroglossal duct cyst
Thyroid eye disease (NORD)
Toxic multinodular goiter
Euthyroid sick syndrome
Subacute granulomatous thyroiditis
Growth hormone deficiency
Constitutional growth delay
Syndrome of inappropriate antidiuretic hormone secretion (SIADH)
Premature ovarian failure
Polycystic ovary syndrome
Androgen insensitivity syndrome
Autoimmune polyglandular syndrome type 1 (NORD)
Multiple endocrine neoplasia
Pancreatic neuroendocrine neoplasms
Opsoclonus myoclonus syndrome (NORD)
Adrenal insufficiency: Pathology review
Adrenal masses: Pathology review
Hyperthyroidism: Pathology review
Hypothyroidism: Pathology review
Thyroid nodules and thyroid cancer: Pathology review
Parathyroid disorders and calcium imbalance: Pathology review
Diabetes mellitus: Pathology review
Cushing syndrome and Cushing disease: Pathology review
Pituitary tumors: Pathology review
Hypopituitarism: Pathology review
Diabetes insipidus and SIADH: Pathology review
Multiple endocrine neoplasia: Pathology review
Neuroendocrine tumors of the gastrointestinal system: Pathology review
Euthyroid sick syndrome
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Brittany Norton, MFA
Tanner Marshall, MS
The term euthyroid sick syndrome, also known as nonthyroidal illness syndrome, can be broken down. Eu- refers to good and -thyroid refers to the thyroid gland which produces thyroid hormones.
So, euthyroid sick syndrome is a state where the thyroid gland is functioning normally, but the thyroid hormones are at abnormal levels.
Normally, the hypothalamus, which is located at the base of the brain, secretes thyrotropin-releasing hormone, known as ΤRH, into the hypophyseal portal system - which is a network of capillaries linking the hypothalamus to the anterior pituitary.
The anterior pituitary then releases a hormone of its own, called thyroid-stimulating hormone, thyrotropin or simply TSH.
TSH stimulates the thyroid gland which is a gland located in the neck that looks like two thumbs hooked together in the shape of a “V”.
If we zoom into the thyroid gland, we’ll find thousands of follicles, which are small hollow spheres whose walls are lined with follicular cells, and are separated by a small amount of connective tissue.
Follicular cells convert thyroglobulin, a protein found in follicles, into two iodine-containing hormones, triiodothyronine or T3, and thyroxine or T4.
Once released from the thyroid gland, these hormones enter the blood and bind to circulating plasma proteins.
Only a small amount of T3 and T4 will travel unbound in the blood, and these two hormones get picked up by nearly every cell in the body.
Once inside the cell T4 is mostly converted into T3, and it can exert its effect. T3 speeds up the basal metabolic rate.
So as an example, they might produce more proteins and burn up more energy in the form of sugars and fats. It’s as if the cells are in a bit of frenzy.
T3 increases cardiac output, stimulates bone resorption - thinning out the bones, and activates the sympathetic nervous system, the part of the nervous system responsible for our ‘fight-or-flight’ response.
Euthyroid sick syndrome (ESS) is a condition in which the thyroid gland is functioning properly, but the thyroid hormone levels are abnormally low. This can lead to a variety of symptoms, including fatigue, weight gain, and hair loss. Common causes of ESS include starvation or a serious illness, and is often seen in critically ill intensive care patients
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