Normal blood calcium levels range between 8.5 and 10.2 milligrams per deciliter, according to MedlinePlus. The calcium blood test measures the amount of calcium attached to blood proteins, while the ionized calcium test measures how much calcium is not attached to these proteins. Results from both give an accurate measurement.
Abnormally high levels of calcium in the blood may indicate prolonged bed rest, consumption of too much calcium, hyperparathyroidism, HIV/AIDS and multiple myeloma, explains MedlinePlus. On the other hand, abnormally low blood calcium levels may be due to kidney failure, liver disease, pancreatitis and a magnesium or vitamin D deficiency.