Which blood collection tube is appropriate for tests requiring serum separation?

The red-top tube is suitable for tests requiring serum separation because it does not contain any additives that could interfere with the biochemical assays being performed. When blood is collected in a red-top tube, it allows the specimen to clot, after which the serum can be separated from the clot through centrifugation. This process results in a clear serum that is necessary for various tests, such as hormone levels, electrolyte panels, and other biochemical analyses. The absence of anticoagulants in this tube allows for proper clotting, leading to accurate test results.

In contrast, the lavender-top tube contains EDTA, an anticoagulant that preserves blood cell components but is not suitable for tests requiring serum, while the blue-top tube contains sodium citrate, which is used for coagulation studies and also prevents clotting. The green-top tube contains heparin, another anticoagulant for plasma tests. Therefore, each of the other tubes serves specific purposes but does not provide serum as the red-top tube does.