The parathyroid consists of are four small glands in the neck located on the thyroid gland. Although these two glands are close in location, their functions are unrelated. The thyroid is responsible for regulating metabolism, so too much thyroid hormone can be associated with weight loss, and too little with weight gain and fatigue. In some cases, when the thyroid is removed surgically, the parathyroid is damaged, resulting in hypoparathyroidism.
The parathyroid regulates concentrations of calcium and phosphorus. It releases parathyroid hormone, which causes calcium to be released into the blood from where it is stored in the bones. The parathyroid regulates blood calcium concentrations, which are important to the nervous system, bone health and muscle contractions. It also regulates concentrations of phosphorus, which works with calcium to maintain strong bones and is necessary for the healthy function of all body cells.
Hyperparathyroidism occurs when the parathyroid produces too much hormone. It causes blood calcium concentrations to rise above the normal range, which is often discovered through a routine blood test. According to the National Endocrine and Metabolic Diseases Information Service, 85 percent of parathyroidism cases are caused by a benign tumor called an adenoma. Symptoms vary in severity and include fatigue, weakness or depression in mild cases. In more severe cases, it can affect appetite, increase thirst and cause mental confusion or memory impairment. Hyperparathyroidism does not affect body weight. Some people affected by parathyroidism have no symptoms at all.
Hypoparathyroidism is much rarer than hyperparathyroidism and occurs when parathyroid hormone concentrations are too low, which causes low concentrations of calcium and phosphorus. Symptoms of low parathyroid hormone include headaches, memory loss, muscle cramps and spasms and tingling in the extremities or lips. Hypoparathyroidism can also cause brittle, dry nails and hair and dental problems, including weak tooth enamel or poorly formed roots. Although hypoparathyroidism can affect the growth of nerves, bones, muscles and teeth, it is not associated with changes in body weight.
Hyperparathyroidism is treated by removing the parathyroid, which is effective in 95 percent of cases. It may also be treated by a drug which stops the parathyroid from secreting hormone. These drugs are called calcimimetics. Some people with mildly elevated calcium concentrations may choose to have their bone density and kidney function monitored instead of having surgery. The treatment for hypoparathyroidism is supplemental calcium and vitamin D. When hypoparathyroidism is not identified and treated promptly, it can result in serious complications, such as cataracts and a blocked airway due to muscle spasms.