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Dose-response relationship between plasma ionized calcium concentration and thrombelastography
Michael F M James1, Anthony M Roche
1Department of Anaesthesia, Groote Schuur Hospital and University of Cape Town, Western Cape, South Africa. james@cormack.uct.ac.za
Journal of Cardiothoracic and Vascular Anesthesia
|December 4, 2004
Summary
A minimum ionized calcium concentration of 0.33 mmol/L is required for blood coagulation to initiate. Calcium levels above 0.56 mmol/L are unlikely to cause coagulation issues, though intermediate levels may affect clot formation rate.
Area of Science:
- Biochemistry
- Hematology
Background:
- Calcium ions (Ca2+) are essential for the coagulation cascade.
- Understanding the precise role of ionized calcium is critical for managing bleeding disorders and during surgical procedures.
Purpose of the Study:
- To determine the threshold for ionized calcium concentration required for blood coagulation.
- To investigate the influence of varying ionized calcium levels on coagulation parameters.
Main Methods:
- An in vitro observational study using 100 samples of citrated blood from healthy volunteers.
- Blood samples were recalcified with varying concentrations of calcium chloride.
- Ionized calcium concentration (Ca2+) was measured using a blood gas analyzer, and coagulation was assessed via thrombelastography.
Main Results:
- No clot formation was observed when ionized calcium concentration was below 0.33 mmol/L.
- Normal coagulation parameters were achieved with Ca2+ levels above 0.56 mmol/L.
- Final clot strength was not affected by Ca2+ once the 0.33 mmol/L threshold was surpassed.
Conclusions:
- An ionized calcium concentration below 0.33 mmol/L is necessary to prevent coagulation.
- Ionized calcium levels exceeding 0.56 mmol/L are unlikely to be the cause of coagulation abnormalities.
- While intermediate Ca2+ levels may influence the rate of clot formation, they do not impact final clot strength.