The normal blood calcium level for adults is 8.8 to 10.4 milligrams per deciliter of blood, according to WebMD. The ionized calcium level for adults is 4.65 to 5.28 milligrams per deciliter. Ionized calcium tests measure the amount of calcium in the blood not attached to protein.
Hyperparathyroidism, cancer, tuberculosis, Paget’s disease and extended bed rest all cause high calcium values in the blood, notes WebMD. Hypoparathyroidism, rickets, kidney failure, the use of laxatives, and osteomalacia cause lower-than-normal calcium levels. Celiac disease, alcoholism and pancreatitis are other causes. Dialysis, medications such as diuretics, and taking calcium supplements prior to the test often cause inaccurate test results.