Causes of high calcium levels in the blood include hyperparathyroidism, multiple myeloma and sarcoidosis, according to the Norman Parathyroid Center. The cause of the condition in more than 99 percent of cases is hyperparathyroidism, which is usually due to a tumor on the parathyroid glands.
Hyperparathyroidism occurs when the body produces too much parathyroid hormone, notes MedlinePlus. The condition often has no known cause, but it is most common in older people, women, and those who have parathyroid cancer or have been exposed to radiation. Symptoms arise when high calcium levels in the blood cause damage to organs or bones, which include bone pain, depression, fatigue, kidney stones and nausea.
Multiple myeloma is a form of cancer that affects the plasma cells, causing them to form groups that build up in the bones, explains Healthline. Doctors do not know what causes the disease, but some risk factors for developing it include being male, exposure to radiation and obesity. Symptoms of multiple myeloma vary for each patient, but can include kidney failure, anemia-related fatigue, bone injuries and repeated infections.
Sarcoidosis is a disease that occurs when the body's organs are inflamed, according to the National Heart, Lung and Blood Institute. Because the inflammation does not go away with sarcoidosis, lumps can form in the organs, affecting how they function. Symptoms vary depending on which organs are affected, but patients typically experience fever, arthritis and enlarged lymph nodes.