Why is citrate not available for microcollection?

Why is citrate not available for microcollection?

• A. Because citrate requires large blood volumes
• B. Because microcollection tubes cannot be colored
• C. Because citrate binds calcium to prevent clotting
• D. Because coagulation is active during dermal puncture

Answer: (D)

The key idea is that the coagulation process starts right away when blood is drawn through a skin puncture, and microcollection relies on very small amounts of capillary blood. Citrate prevents clotting by binding calcium, but it must be present in a precise blood-to-anticoagulant ratio to work properly. With the tiny volumes in microcollection, and the immediate onset of coagulation during the dermal puncture, it’s not feasible to guarantee the correct ratio and to prevent clotting reliably. That’s why citrate isn’t used for microcollection.

The key idea is that the coagulation process starts right away when blood is drawn through a skin puncture, and microcollection relies on very small amounts of capillary blood. Citrate prevents clotting by binding calcium, but it must be present in a precise blood-to-anticoagulant ratio to work properly. With the tiny volumes in microcollection, and the immediate onset of coagulation during the dermal puncture, it’s not feasible to guarantee the correct ratio and to prevent clotting reliably. That’s why citrate isn’t used for microcollection.