What causes high calcium levels?

High levels of calcium in the blood are typically linked to primary hyperparathyroidism, cancer, thiazide diuretics and kidney disease, according to University of California at Los Angeles medical experts. Since dehydration or laboratory error may trigger a high reading, a second test may be administered to confirm hypercalcaemia.

The most common is primary hyperparathyroidism, a disease where a tumor in the parathyroid gland pulls large amounts of calcium from the bones for deposit into the bloodstream. Cancers of the lung, breast, esophagus, mouth, tongue, lip, kidney, ovary, uterus and cervix may cause cancer to leak from the bones into the bloodstream. Thiazide diuretics used to treat high blood pressure sometimes cause the kidneys to retain calcium rather than deposit it into the urine. In those with reduced kidney function, imbalances in bone metabolism often trigger calcium to deposit into the blood vessels.