Definition
cCa2+(P) is the concentration of ionized calcium (Ca2+) in plasma. The systematic symbol for arterial blood is cCa2+(aP). The analyzer symbol may be Ca2+ or cCa2+.
What does cCa2+ tell you
Ionized calcium in plasma is the metabolically active part of total calcium, making up around 50 % of the total calcium. Total calcium in plasma is in part bound to proteins and to bicarbonate. The binding to proteins depends on pH. It will also readily bind itself to other anions, if available (heparin, citrate, etc.).
The ionized calcium is necessary for a number of enzymatic processes and membrane transport mechanisms. It thereby plays a key role in blood coagulation, cellular growth, neuro-muscular transmission, and a series of other functions essential to life.
Reference ranges
cCa2+(aP) reference range (adult): 1.15-1.29 mmol/L
disclaimer
Clinical interpretation
A. Low values of cCa2+ can be caused by:
- Alkalosis
- Renal failure
- Acute circulatory insufficiency
- Lack of vitamin D
- Hypoparathyroidism
B. High values of cCa2+ can be caused by:
- Malignancies
- Thyreotoxicosis
- Pancreatitis
- Immobilization
- Hyperparathyroidism
Considerations
cCa2+ is the electrolyte parameter most sensitive to the use of non-electrolyte-balanced heparin. When measuring cCa2+, it is therefore recommended always to use electrolyte-balanced heparin. For more information, go to Preanalytical considerations.
