The prothrombin time test: effect of varying citrate concentration

Area of Science:

• Hematology
• Clinical Chemistry

Background:

• Accurate anticoagulation is crucial for reliable blood sample analysis.
• Trisodium citrate is a common anticoagulant, but its optimal concentration requires careful consideration.
• Variations in citrate concentration can affect key hematological and coagulation parameters.

Purpose of the Study:

• To evaluate the impact of different trisodium citrate concentrations on blood anticoagulation.
• To assess the effect of varying citrate levels on plasma prothrombin time and haematocrit.
• To determine the influence of anticoagulation protocols on laboratory testing accuracy.

Main Methods:

• Blood samples from normal subjects and patients on oral anticoagulants were used.
• Samples were anticoagulated with four different trisodium citrate concentrations (0.09-0.15 M).
• Haematocrit and plasma prothrombin time were measured using standardized recalcification with CaCl2.

Main Results:

• Different trisodium citrate concentrations led to measurable changes in haematocrit.
• Plasma prothrombin time varied significantly across the tested citrate concentrations.
• Inter-laboratory variability in prothrombin time techniques was also observed.

Conclusions:

• The concentration of trisodium citrate used for anticoagulation significantly affects haematocrit and plasma prothrombin time measurements.
• Careful selection of citrate concentration is essential for accurate laboratory diagnostics.
• Standardization of anticoagulation protocols across different laboratories is recommended.