What anticoagulant is in a serum separator tube?

A serum separator tube (SST) typically does not contain an anticoagulant; instead, it contains a gel that separates serum from blood cells after centrifugation. The tube is often used for tests requiring serum, which is obtained after allowing the blood to clot and then centrifuging the sample. This process makes it ideal for various laboratory tests that analyze serum components. Some tubes may contain additives like clot activators to expedite clotting, but they do not act as anticoagulants.