The thyroid gland is a small, butterfly-shaped gland located at the base of your neck. It has a left lobe and a right lobe, both connected by an isthmus. The thyroid gland regulates your body’s metabolism and growth. The thyroid gland does so through two hormones thyroxine (T4) and triiodothyronine (T3). The production of these hormones by the thyroid gland is stimulated by thyroid-stimulating hormone (TSH). TSH is secreted by the pituitary gland, a small gland the size of a peanut at the base of the brain. The thyroid gland uses dietary iodine to make these hormones. T3 is the more active form of the enzyme and once released from the thyroid T4 is converted to T3 in the periphery.
You can experience various symptoms when your thyroid gland underproduces or overproduces these hormones. The underproduction of these hormones causes hypothyroidism, which causes weight gain, cold intolerance, muscle fatigue, lethargy, excessive menstrual bleeding, constipation, dull facial expression, and depression. It can cause infertility as well. Overproduction of these hormones causes hyperthyroidism, which causes weight loss, heat intolerance, muscle weakness, diarrhea, and nervousness.
Hyperthyroidism can be caused by several things:
• Graves’ disease — an autoimmune disorder
• lumps (nodules) on your thyroid
• goiter — swelling of your thyroid gland.
• medications containing iodine.
Hypothyroidism can be caused by:
• Hashimoto’s thyroiditis — an autoimmune disorder in which your body produces antibodies that attack your thyroid gland.
• treatment for hyperthyroidism.
• Surgical removal of the thyroid gland.
• postpartum thyroiditis — your thyroid becomes inflamed within the first year after pregnancy.
• iodine deficiency
• medications containing iodine e.g., amiodarone.
Hyper/ Hypothyroidism is diagnosed by measuring your TSH, T3, and T4 levels. These thyroid disorders can be overt, causing symptoms or subclinical, not causing symptoms. Subclinical hyperthyroidism is characterized by normal T4 and T3 levels and a suppressed TSH level. Subclinical hypothyroidism is characterized by normal T4 and T3 levels and an elevated TSH level. Even though the subclinical hypo/hyperthyroidism does not cause symptoms, they need to be treated as well. Untreated subclinical hypothyroidism can cause elevated cholesterol levels and eventually lead to cardiovascular disease and dementia. Untreated subclinical hyperthyroidism can lead to palpitations and osteoporosis.
Hypothyroidism is usually treated with a medication called levothyroxine — a hormone replacement tablet. And hyperthyroidism is usually treated with either medication, radiation, or surgery.