Question 77

Sodium citrate is the appropriate additive for a coagulation specimen.

Sodium citrate is the correct additive used in tubes for coagulation studies, as it effectively binds calcium, which is essential in the clotting process.

A) Lithium heparin

Lithium heparin is not suitable for coagulation specimens because it acts as an anticoagulant by inhibiting thrombin and factor Xa, which can interfere with the coagulation pathways being assessed. Therefore, it is not the appropriate choice for tests requiring accurate coagulation results.

B) Sodium heparin

While sodium heparin is also an anticoagulant, it is primarily used for plasma chemistry tests and does not provide the optimal conditions for coagulation studies. The presence of heparin can alter the results of coagulation tests, making it an incorrect choice.

C) EDTA

EDTA is an anticoagulant that binds calcium ions; however, it is primarily used for hematological tests rather than coagulation studies. Its use can lead to erroneous results in coagulation assays, thus making it unsuitable for this purpose.

D) Sodium citrate

Sodium citrate is the preferred additive for coagulation specimens as it effectively chelates calcium ions, which is necessary for the coagulation cascade. This allows for accurate measurement of coagulation factors and ensures that the results reflect the true coagulation status of the patient.

Conclusion

Sodium citrate is definitively the right choice for coagulation specimens due to its role in binding calcium, which is critical for accurate coagulation testing. In contrast, the other options—lithium heparin, sodium heparin, and EDTA—are either unsuitable or can interfere with coagulation assessments, leading to inaccurate results.