Most of the calcium in your body is in your bones, with less than 1 percent of calcium in your blood. Because the concentration is so small, it is important the amount of calcium in your blood remains constant. When the amount of calcium in your blood rises, a condition called hypercalcemia, it can lead to disruptions in physiological processes. Hypercalcemia may occur for various reasons.
Hyperparathyroidism
The leading cause of hypercalcemia in the human body is hyperparathyroidism, or overactive parathyroid glands. The parathyroid glands, which lie directly behind the thyroid gland in your neck, regulate your blood calcium levels. When the levels of calcium in your blood fall, the parathyroid glands produce parathyroid hormone, which triggers your bones to release calcium. When the parathyroid glands are overactive, they continuously release parathyroid hormone even when your blood calcium levels are normal. As a result, blood calcium levels accumulate to abnormal levels.
Hyperparathyroidism may occur as a result of benign or cancerous parathyroid tumors, enlargement of the parathyroid glands, calcium deficiency, vitamin D deficiency or kidney disease.
Cancer
Certain types of cancer may also lead to hypercalcemia. Some cancerous tumors, especially those associated with lung cancer, breast cancer and multiple myeloma, create a protein with actions similar to parathyroid hormone. Like parathyroid hormone, these proteins trigger your bones to release calcium, increasing your blood calcium levels. As cancer spreads, your risk of developing hypercalcemia increases, according to MayoClinic.com.
Excess Supplementation
Consuming too much calcium from supplements can cause the levels of calcium in your blood to rise. Excess vitamin D supplementation can also lead to hypercalcemia. Vitamin D increases the rate at which you absorb calcium from your digestive tract. When you consume excessive amounts of the vitamin, the amount of calcium your body absorbs may be disproportionate to the amount it actually needs.
Granulmatous Diseases
Granulmatous diseases are those characterized by inflammation caused by injury to body tissues. When your tissues are inflamed, your body releases calcitriol, a form of vitamin D that controls your blood calcium levels. The release of calcitriol results in increased absorption of calcium in the digestive tract. When you absorb more calcium, your blood calcium levels rise. Examples of granulmatous diseases include tuberculosis and sarcoidosis.
Dehydration
Your blood is a delicate balance of water, electrolytes and minerals, like calcium. Dehydration, which occurs when the volume of water in the body is lower than normal, can disrupt the balance in your blood. When the amount of water in your blood decreases, the calcium concentration rises.
