Calcium in plasma/serum 2,15 – 2,51 mmol/L
The element calcium is found in the body as divalent cations (Ca2+). Almost all of the calcium (25-35 mol or 1000-1400 g in total) is found in the bones. About 50 % of calcium in plasma is unbound and biologically active, 40 % is bound to albumin, while 10 % is bound to anions such as bicarbonate, citrate, phosphate, and lactate. Changes in the concentration of albumin or acid-base imbalances will result in unreliable measurements of unbound calcium.
Read more about calcium in The handbook on medical biochemistryy.