Hypothyroidism also occur as a result of, pituitary

Hypothyroidism is a condition characterized by decreased secretion of thyroid hormones- tetraiodothyronine (T4) and triiodothyronine (T3)- from the thyroid gland, which is located in the front lower part of the neck. The thyroid gland is an endocrine gland that secretes hormones directly into the bloodstream. Symptoms of hypothyroidism develop slowly, often over a span of several years. Initially, an individual may feel lethargic and later develop signs and symptoms of a slowed-down metabolism, feeling cold, muscle weakness, weight gain, joint or muscle pain, depression, pale, dry skin, thinning of hair, a slow heart rate, high LDL cholesterol and irregular menstrual bleeding9. There are three primary disease types which include: Primary hypothyroidism, Secondary hypothyroidism and Tertiary hypothyroidism. Primary hypothyroidism occurs when the thyroid gland does not produce a sufficient amount of the thyroid hormone to maintain the body’s metabolism and heat production3. The decrease of TH production can result from congenital defects of the thyroid gland, surgical removal of the gland and radiation treatment for thyroid cancer or Hashimoto’s thyroiditis-an autoimmune disorder9. Furthermore, medications that contain iodine, such as amiodarone can contribute to the development of hypothyroidism. A decrease in TH levels contributes to increased serum cholesterol and can place an individual at higher risk for the development of atherosclerosis and cardiac disease3. Furthermore, the release of the thyroxin hormone (T4) is reduced, leading to the loss of the negative hormonal feedback system on the thyroid-stimulating hormone (TSH) produced by the posterior pituitary gland3. As a result, there is an increased concentration of TSH and tetraiodothyronine (T4) is converted into triiodothyronine hormone (T3) at the target tissues. Levothyroxine drug is the most communal treatment option, as it has been shown to decrease the TSH levels and in turn, increase the free T4 in the body. Furthermore, Triiodothyronine-levothyroxine combination therapy studies show affirmative results in some individuals and Triiodothyronine-only treatment is shown to associate with a decrease in body weight and an improved lipid profile4.Secondary (central) hypothyroidism occurs due to the interference of diseases with the thyrotropin-releasing hormone production by the hypothalamus and its delivery via the pituitary stalk, or with the production of the pituitary thyrotropin11. Secondary hypothyroidism may also occur as a result of, pituitary adenomas, radiotherapy, head trauma and pituitary apoplexy. It is characterized by the malfunction of the pituitary gland in secreting TSH10. As a result, there is a low concentration of TSH and free T4. It has been denoted that glucocorticoid treatment may be an option for individuals suffering from Secondary (central) hypothyroidism. In high doses, glucocorticoids reduce the conversion of T4 to the more active T3. As, TSH synthesis is determined by the balance of positive and negative regulation by TRH and T39. Lastly, Tertiary hypothyroidism refers to the malfunction of the hypothalamus in secreting the thyroid releasing hormone2. Possible treatments involve, thyroid replacement therapy, cessation of drugs with lithium or dopamine, thyroxine replacement therapy, surgery and glucocorticoid treatment5.