<prompt> The per cent of Free or Ionized Calcium in the body is10255075  <response>: C 50 IONIZED CALCIUM: Total calcium consists of free or ionized calcium 50, calcium bound to protein 40-45, principally albumin and calcium complexed to anions 5-10, E.g. citrate, lactate, bicarbonate. Total calcium level does not give an indication of what is available at the cellular level. Ionized calcium iCa is the form of calcium that is readily available to cells, and measurement of iCa is a more accurate reflection of the physiological calcium state. Measurement of ionized calcium requires instrumentation with ion-specific electrodes. Unlike total calcium, ionized calcium is unaffected by albumin concentration, but it is affected by acid-base balance. Acidosis decreased pH increases iCa, where as Alkalosis increased pH decreases iCa. The pH of blood, serum or plasma changes rapidly with storage usually decreases with refrigeration and increases with freezing, therefore iCa is unstable in stored blood samples. 