The normal range of calcium levels in blood is 8.5 to 10.2 milligrams per deciliter, explains the National Institutes of Health. However, normal value ranges may vary slightly due to different methods of testing in laboratories. Doctors can interpret the test results and advise the patient accordingly.
Common causes of abnormally high calcium levels include long-term bed rest, excessive consumption of calcium or Vitamin D, HIV or AIDs. Additional causes include hyperparathyroidism, hyperthyroidism, Paget's disease, sarcoidosis, tumors and use of medications such as lithium, tamoxifen and thiazides, says the National Institutes of Health. Common causes of abnormally low calcium levels include intestinal malabsorption, kidney failure or a deficiency in Vitamin D or magnesium; in addition to liver disease, pancreatitis, hypoparathyroidism and low albumin levels.