An elevated calcium level indicates that too much calcium is present in the blood, according to Mayo Clinic. Hypercalcemia is the medical term for high levels of calcium, and the most common cause is overactive parathyroid glands.
The four parathyroid glands are located around the thyroid gland, and each is about the size of a grain of rice, explains Mayo Clinic. Parathyroid glands regulate calcium in the body and release a hormone that signals the bones to release calcium into the blood stream. Other causes of hypercalcemia include cancer, immobility, medications, supplements, hereditary disorders, dehydration, and diseases that raise the levels of vitamin D in the blood stream.