Which tube type is typically used to obtain serum for testing after the blood has clotted?

Which tube type is typically used to obtain serum for testing after the blood has clotted?

• A. SST
• B. EDTA
• C. Sodium Citrate
• D. Sodium Fluoride

Answer: (A)

Serum is the liquid portion that remains after blood has clotted and is separated from the clot. To get serum, you need a tube that promotes clotting and then allows easy separation of the serum from cells. The serum separator tube (SST) contains a clot activator to speed clotting and a gel that, after centrifugation, forms a barrier between serum and the clot. This yields clean serum ready for testing. The other tubes contain additives that prevent clotting or preserve plasma (EDTA and sodium citrate are anticoagulants; fluoride with oxalate is another anticoagulant/antiglycolysis tube), so they produce plasma rather than serum. Therefore, SST is the best choice for obtaining serum after the blood has clotted.

Serum is the liquid portion that remains after blood has clotted and is separated from the clot. To get serum, you need a tube that promotes clotting and then allows easy separation of the serum from cells. The serum separator tube (SST) contains a clot activator to speed clotting and a gel that, after centrifugation, forms a barrier between serum and the clot. This yields clean serum ready for testing. The other tubes contain additives that prevent clotting or preserve plasma (EDTA and sodium citrate are anticoagulants; fluoride with oxalate is another anticoagulant/antiglycolysis tube), so they produce plasma rather than serum. Therefore, SST is the best choice for obtaining serum after the blood has clotted.