The anticoagulant required for routine coagulation testing is

• A. Sodium heparin
• B. Sodium citrate
• C. Acid citrate dextrose
• D. Sodium fluoride

Answer: (B)

The essential idea is to stop clotting in a way that can be reversed for accurate coagulation testing. Sodium citrate does this by binding calcium ions, which are necessary cofactors for nearly all steps of the coagulation cascade. With calcium chelated, blood does not clot during collection and handling, allowing the plasma to be analyzed.

For the actual tests, calcium is added back (recalcification) in the assay, so the coagulation sequence can proceed under controlled conditions. This reversibility, plus the standard, well-characterized blood-to-citrate ratio (which preserves factor activity and minimizes interference), makes sodium citrate ideal for routine coagulation tests like PT and aPTT.

Other options either interfere with the tests or are used for different purposes. Sodium heparin also prevents clotting but can affect clot-based assays and isn’t the standard for routine coagulation testing. Acid citrate dextrose is used mainly for blood banking and some specialized tests, not routine coagulation panels. Sodium fluoride is a glycolysis inhibitor used for glucose testing, not as an anticoagulant for coagulation studies.

So, the anticoagulant routinely used for coagulation testing is sodium citrate.