Calcium is an important nutrient that the body needs to help keep bones strong and healthy. High blood calcium usually doesn't cause any symptoms, but over time, too high calcium levels can cause symptoms and health problems. Hypercalcemia is an increase in the level of calcium in the blood due to other conditions. The extra calcium can cause a variety of health problems, such as brittle bones, kidney stones, and heart and brain problems. Normally, the body controls blood calcium levels through several hormones, but more than 25 diseases and conditions, such as cancer, kidney problems, medication problems, or severe dehydration, can lead to hypercalcemia. The main causes of high calcium include: Hyperparathyroidism, a condition in which four pea-sized glands behind the thyroid gland (parathyroid glands) begin to secrete too much parathyroid hormone (PTH), regardless of calcium levels. This results in an abnormally high level of calcium in the blood. Hyperparathyroidism accounts for nearly 90% of cases of hypercalcemia. About 100,000 people in the United States develop hyperparathyroidism each year. Postmenopausal women are at the highest risk. Drugs. Some medications and dietary supplements can cause calcium levels in the blood to rise. These include: cancer. Certain types of cancer, such as blood, lung, or breast cancer, can also cause hypercalcemia. This can be due to bone metastases or hormones produced by certain types of cancer. If you have mild hypercalcemia, you may not notice any symptoms. However, in severe cases, it can affect different parts of the body. Symptoms can include: Tell your doctor if you notice any signs or symptoms. High levels of calcium in the blood can lead to other health complications, such as osteoporosis. Hyperparathyroidism can cause bones to release large amounts of calcium into the bloodstream, making them thinner and weaker. This is known as osteoporosis. It increases the chances of fractures and spinal problems. Kidney stone. Too much calcium in the urine can form small and painful stones in the kidneys. Passing stones can be very painful. Kidney failure. Hypercalcemia affects the way the kidneys work, making it difficult to eliminate toxins and purify the blood. Problems with brain function. High levels of calcium in the blood can cause neurological problems and impair thinking skills. It can cause confusion, dementia, and in severe cases, coma. Heart problems. Abnormally high calcium levels can cause abnormal electrical impulses in the heart, which can lead to irregular heartbeats (arrhythmias). Because there are few obvious symptoms or signs of hypercalcemia, you may not know that your blood calcium levels are too high until your doctor checks them out. Your doctor may order blood tests to check for hypercalcemia. Blood tests can also determine whether the parathyroid glands secrete high levels of PTH. This can help doctors diagnose hyperparathyroidism, which is often the cause of hypercalcemia. If your doctor suspects that hypercalcemia is due to another condition, such as cancer, you may order imaging tests, such as X-rays, MRI or CT scans, to examine your lungs and bones. Your doctor will make a treatment plan based on the severity of your hypercalcemia. If it is mild, your doctor may choose to monitor calcium levels closely and recommend: If hypercalcemia is severe, treatment options may include medication or surgery. Medications may include: If hypercalcemia is caused by hyperparathyroidism, your doctor may recommend surgery to remove the affected gland.