Thyroid and Parathyroid Glands

The thyroid is the largest and one of most important glands in the human body. It is a butterfly-shaped gland located in the middle of the neck, just below the voice box and just above the collar bones. The major function of the thyroid gland is to produce thyroid hormone (TH) which regulates the rate with which the human body utilizes energy while performing its vital functions (metabolism). Often referred to as the body's metabolic hormone, the thyroid hormone regulates the metabolism of the human body by increasing cellular activity through the activation and stimulation of enzymes that combine oxygen and glucose, a process that increases your basal metabolic rate (BMR) and body heat production. TH is also critical for nervous system development and maintenance. In addition, the hormone regulates tissue growth and development and helps maintain normal blood pressure, Malfunctions of the thyroid can cause many disorders and diseases. The thyroid gland can malfunction mostly in two different ways. It can produce or release a very low level of thyroid hormone, resulting in a condition commonly known as hypothyroidism (underactive thyroid). It can also produce or release too much thyroid hormone, resulting in what is commonly known as hyperthyroidism (overactive thyroid). When too little thyroid hormone is synthesized and secreted by the thyroid gland, the body's metabolic rate decreases, and the function and performance of the body slows down. This condition can make us feel depressed and tired, make the muscles weak, impair the memory, cause weight gain, cause less bowel movement, slow down the heart rate, cause low body temperature, and may result in irregular or heavy menstruation or infertility in women. When too much TH is produced and released by the thyroid, the body's metabolic rate increases, resulting in increased metabolic rate. Symptoms of hyperthyroidism include nervousness/irritability, fast/irregular heart rate, weight loss, enlarged thyroid gland (goiter), increased body heat, increased perspiration, sleep disturbances (insomnia), more frequent bowel movements, and shorter and scantier menstrual flow in females. Parathyroid Parathyroid glands are four small endocrine glands located in the neck behind the thyroid. The main function of the parathyroid glands are to control calcium levels within the blood. Calcium makes our bones hard and strong. Without calcium, our bone would be soft and fragile. Calcium levels in the bones are controlled and regulated by the parathyroid glands. Through the production and release of parathyroid hormone (PTH), these four small glands, which are normally the size and shape of a grain of rice, determine how much calcium is absorbed from diet, how much is released in urine by the kidneys, how much is retained within the nervous system and muscles, and how much is stored in the bones. The parathyroid glands are activated to release PTH when the blood level of calcium becomes low. PTH increases blood calcium by stimulating bone cells to be released from bones. PTH also increases the absorption of calcium from the digestive tract by activating vitamin D, therby facilitating calcium uptake by the kidneys. Abnormal secretions of PTH are causes of disorders in humans, especially bone diseases. One or more of the four parathyroid glands may go bad resulting in the relase of abnormal levels of PTH. Too much production of PTH (hyperparathyroidism) by an overactive parathyroid results in increased concentrations of calcium in the blood. In individuals with hyperparathyroidism, one or more of the parathyroid glands might be out of control and continue to make large amounts of parathyroid hormone regardless of the high levels of calcium already circulating in the blood. The development of benign tumor in any of the parathyroid glands is the most cause of hyperparathyroidism. The symptoms of hyperparathyroidism can aptly be described as “moans, groans, stones, and bones.” Persistent elevated calcium levels due to overproduction of PTH results in pains in the bones and osteoporosis, a term that describes the loss of calcium in the bones. In severe cases, the bones become brittle and break. Bones with osteoporosis can often ache and hurt. Osteoporosis occurs in almost all individuals with parathyroid disease. The problem of osteoporosis is more of a concern in elderly females. Hyperparathyroidism can also initiate and cause development of gastric ulcers, and inflammation of the pancreas (pancreatitis). High calcium blood levels can also cause the linings of the stomach and the pancreas to become inflamed and painful (ulcers and acute pancreatitis). Persistently elevated blood calcium level leads to development of kidney stones. Because the major function of the kidney is to filter and clean the blood, the kidneys are constantly exposed to high levels of calcium in individuals with hyperthyroidism. Constant filtering of large amounts of calcium within the renal tubules results in kidney stones. Due to deposition of large amounts of calcium within the kidney, the entire organ can become calcified and in extreme cases, the kidneys may take on bone characteristics. This condition can be very painful and may cause kidney failure. The overall dangers of hyperthyroidism include osteoporosis, bone fractures, kidney stones, peptic ulcers, and pancreatitis. In contrast, inadequate production of PTH (hyperparathyroidism) results in decreased concentrations. The resulting low levels of calcium often lead to tetany and convulsions, and can be life-threatening.