Normal serum level of total calcium ranges between 8.5 - 10.5 mg/dL
The amount of total calcium varies with the level of serum albumin, a protein to which calcium is bound. The biologic effect of calcium is determined by the amount of ionized calcium, rather than the total calcium. Ionized calcium does not vary with the albumin level, and therefore it is useful to measure the ionized calcium level when the serum albumin is not within normal ranges, or when a calcium disorder is suspected despite a normal total calcium level.
Normal ionized calcium ranges between 4.5 - 5.6 mg/dL