Proper function of the human body is dependent on many aspects, such as the relationship between the parathyroid hormone and calcium levels in the blood. Calcium is a necessary component for proper bodily function, but an increase in calcium levels can cause several problems. For this reason, the parathyroid hormone is released into the bloodstream to help maintain proper calcium levels. So the relationship between the parathyroid hormone and calcium is this: if calcium levels fall too low, the hormone is released in order to mobilize calcium into the blood. If calcium levels become too high, the hormone is largely silenced to allow calcium to be removed from the body.
Calcium has many functions, including being used by the nervous system to conduct electrical impulses across nerves, providing energy to muscles allowing them to contract, and also helping to strengthen bones. Without proper calcium levels in the body, a person could develop neurological problems such as depression and changes in personality, and physical problems such as weak bones and muscle cramps. Thus, the parathyroid hormone and calcium levels are constantly checked and balanced by the parathyroid gland. This gland is a rice-to-pea shaped gland that resides behind the thyroid. Most people have four of these glands, but some people may have anywhere from two to twelve.
To counteract falling calcium levels, the parathyroid hormone signals osteoclasts — certain cells within the bones — to reabsorb bone matter, releasing calcium into the blood. In addition, the hormone also directs the kidneys to retain calcium so that the mineral can build up. Lastly, it tells the kidneys to make an active form of vitamin D, a vitamin that facilitates the absorption of calcium within the intestines. Functioning properly, the parathyroid gland maintains the proper relationship between the parathyroid hormone and calcium levels. If the gland is not working properly, a person’s life or health could come in jeopardy.
Hyperparathyroidism, a disease in which the parathyroid gland is producing too much parathyroid hormone, can cause the connection between the parathyroid hormone and calcium to become imbalanced. This disease can be the result of many factors. For instance, a tumor could cause the parathyroid to continue releasing the hormone even though calcium levels are normal. In addition, a lack of calcium or vitamin D in a person’s diet can cause the hormone to be constantly released in an attempt to return calcium levels to normal. Hypoparathyroidism occurs when the parathyroid gland is not producing enough hormone and may occur if the glands are removed or are destroyed. This disease may cause calcium levels to drop which can result in seizures and tetany, or muscle spasms.