Specimen must not be exposed to air. Supply either a separate, full serum container or a venous or arterial specimen collected in a syringe as for Blood Gases.
Mix well and deliver immediately.
Note: Syringes containing 125 USP units of heparin are unsuitable due to binding of ionised calcium.
This test may be of value when doubt exists about calcium status in the presence of hypoalbuminaemia and in acid/base disturbances.
Stasis must be avoided when taking blood as prolonged use of a torniquet gives falsely high values, as does haemolysis.