Behind and near to the thyroid gland are other glands which are known as parathyroid glands, their chief function being control of the use of calcium and phosphorus by the body. Apparently this gland responds with secretion of its hormone when the amounts of calcium and phosphorus in the serum of the blood become insufficient. However, extracts of the parathyroid gland have been prepared and are used in cases where people apparently suffer from a lack of parathyroid hormone. The lack of this hormone is made evident by such symptoms as tremors of the body, called “tetany,” which occurs also with insufficiency of calcium. The tetany or tremors, which are like muscle spasms or cramps, are due to extra excitability of the nerves controlling the muscles.
Obviously the condition may be controlled by giving extra calcium directly into the blood or by taking large amounts of calcium by mouth. The condition may also be controlled by direct injection of the parathyroid hormone. Calcium is also controllable through the use of vitamin D or of a substance like vitamin D called dihydrotachysterol. The action of this substance is more like the action of the parathyroid hormone than is vitamin D itself.
In the treatment of this condition, the diet should be one which contains much calcium and relatively little phosphorus. The foods which are rich in calcium are milk and cheese products and the leafy green vegetables. Milk also, however, includes phosphorus, as does egg yolk, cauliflower and molasses.
As might be expected, excessive action of the parathyroid glands results in changes of the bones of the body, because the bones are largely made up of calcium. Since the parathyroid glands so definitely control the use of calcium by the body, some have thought that kidney stones might be due to some action of the parathyroid glands. This has not, however, been established with certainty. Cases of excessive action of the parathyroid gland can occur without any’ evident changes in the bones and, in fact, the condition may be more frequent than is now suspected. There may be excessive growth of the tissues of the parathyroid glands which can result in excessive activity.
When large amounts of extra calcium are found in the blood and with that muscular weakness, loss of appetite, and pain in the bones, and, not infrequently, excessive elimination of fluid through the kidneys, the physician suspects excessive action of the parathyroid glands. There are many different conditions which can interfere with the growth of bones, so that studies of the blood as to the amount of calcium and the manner in which the body handles calcium are fundamental in discovering whether or not disturbance of the bone growth is due to excessive action of the parathyroid gland, or to some other cause.
Since vitamin D has become available as a concentrate, and since people have been taking exceedingly large doses of vitamin D to treat a variety of conditions, difficulty has occurred in recognizing the difference between excessive vitamin D in the body and excessive action of the parathyroid glands.
In every case of hyperparathyroidism the possibility of surgical removal of excess tissue of the parathyroids must be considered as primary in the treatment.