The Function of the Thyroid Gland

The thyroid gland secretes hormones which control the body's metabolic rate in two primary ways: by stimulating tissue response in the body to produce proteins, and by increasing cell oxygenation. To produce these vital hormones, the thyroid needs the element iodine, which is ingested from food and water.

The regulation of thyroid hormone levels is controlled by several mechanisms. The hypothalamus, located in the brain just above the pituitary gland, secretes thyrotropin-releasing hormone, which triggers the pituitary to release thyroid-stimulating hormone (TSH). When the amount of thyroid hormone in the blood reaches a certain level, the pituitary will produce less thyroid-stimulating hormone; conversely, when the amount of thyroid hormone in the blood decreases to a certain level, the pituitary produces more thyroid-stimulating hormone.

There are two forms of thyroid hormone. Thyroxine (T4), produced in the thyroid, has only a slight impact on speeding up the body's metabolic rate. Thyroxine is converted by the liver and other organs to triiodothyronine (T3), which is the metabolically active form. In this way, the body will maintain the proper levels of thyroid hormone to regulate normal metabolic rate.

Thyroid Deficiency and Diagnosis

Euthyroid Sick Syndrome(ESS)
An abnormal thyroid function where one typically suffers from severe non-thyroid systemic illness.
Conditions commonly associated with ESS include fasting, malnutrition, surgical trauma, etc.

Hyperthyroidism
Types include

• Graves’ Disease :- characterised by goiter, myxedema. Common symptoms are goiter, tachycardia, tremor, warm, moist skin, eye signs & atrial fibrillation.
• Thyroid storm :- characterised by symptoms of thyrotoxicosis. Symptoms are varied including fever, muscle weakness, confusion, psychosis, or coma.
• T3 Toxicosis
• Plummers disease
• Thyrotoxicosis factitia

Treatment can include iodine therapy (30 drops of lugols Iodine per day), propylthiouracil, propranalol, corticosteroids, etc.

Hypothyroidism
This deficiency occurs when the thyroid gland is producing too little thyroid hormone. The symptoms of hypothyroidism are gradual and are sometimes mistaken for depression. Symptoms are varied & include dull facial expression, a hoarse voice, droopy eyelids, and puffy and swollen face and eyes. Hypothyroidism can cause a number of other conditions, such as allergies, skin problems, fatigue, nervousness, gaining or losing weight, brittle nails, dry skin, sparse hair, gastrointestinal problems (constipation), frank psychosis ( myxedema madness), infertility, bradycardia, mental sluggishness, low immune function, depression, and cold intolerance.

Primary Hypothyroidism is the most common form of thyroid hormone deficiency in adults, with Secondary Hypothyroidism occurs where there is a failure of the hypothalamic-pituitary axis.