What is hypercalcemia? Calcium is an essential mineral that plays a vital role in many different bodily functions. For example, strong bones require constant metabolism of calcium to generate bone matrix. The healthy parathyroid glands regulate the amount of calcium that circulates in the blood. Hypercalcemia is a condition in which the blood has too much calcium. Calcium is a mineral that is essential for many aspects of health, including the health of bones and teeth and a normal heart rhythm. Calcium is also required for muscle contractions and relaxation, nerve and hormone function, and blood pressure regulation. Calcium must be consumed in your diet, absorbed by your digestive system, and eliminated or removed from your body effectively, in order to maintain optimal health. Most people get calcium by eating a variety of foods rich in calcium. Foods that naturally contain calcium include milk and other dairy products; green, leafy vegetables; seafood; nuts; and dried beans. Calcium is also added to orange juice, breakfast cereals, breads, and other fortified food products. After consuming these sources of calcium, the body then eliminates excess or unused calcium through urine, stool and sweat. Hypercalcemia occurs when the body does not effectively regulate and eliminate calcium. Hypercalcemia is most commonly caused by primary hyperparathyroidism, a condition in which the parathyroid glands, which are located in the neck, overproduce parathyroid hormone (PTH). PTH is one of the main regulators of calcium, along with vitamin D. Certain types of cancer can also cause hypercalcemia, especially breast and lung cancer. The National Cancer Institute estimates that 10% to 20% of patients with cancer will develop hypercalcemia (Source: NCI). Hypercalcemia is often mild and does not produce symptoms, so you may only become aware of high blood calcium levels through a laboratory test. When symptoms are noticeable, they can include excessive urination, fatigue, nausea and vomiting, decreased appetite, excessive thirst, bone pain, and abdominal or flank pain. Untreated hypercalcemia can lead to serious complications, such as osteoporosis, kidney stones, kidney failure, and bone fractures. Seek regular medical care and follow your treatment plan to reduce the risk of serious long-term complications from hypercalcemia. Seek immediate medical care (call 911) if you, or someone you are with, are unable to walk normally after a fall or other injury, or have severe flank or abdominal pain, which may occur with bloody urine or an inability to urinate.