Which tube is used for chemistry panels and serology tests and contains a gel barrier but no additive?

Which tube is used for chemistry panels and serology tests and contains a gel barrier but no additive?

• A. Gray Tube — Na Fluoride/K Oxalate
• B. SST (Tiger Top) — No additive, gel barrier
• C. Red Tube — No additive
• D. Lavender Tube — EDTA

Answer: (B)

The main idea is that chemistry panels and serology require serum, not plasma, and that a gel barrier helps keep that serum clean from cellular components after centrifugation. A serum separator tube is designed to clot blood and then use a thixotropic gel to form a barrier between the serum and the clot and cells. Since there’s no anticoagulant, the blood can clot, producing serum, and the gel barrier stabilizes the sample for downstream chemistry and serology tests. That combination—serum-producing without anticoagulant plus a gel barrier—makes this tube the best fit for chemistry panels and serology. Other tubes don’t fit this need because they contain additives that prevent clotting (gray with fluoride/oxalate, lavender with EDTA) or lack a gel barrier (red top without a gel).

The main idea is that chemistry panels and serology require serum, not plasma, and that a gel barrier helps keep that serum clean from cellular components after centrifugation. A serum separator tube is designed to clot blood and then use a thixotropic gel to form a barrier between the serum and the clot and cells. Since there’s no anticoagulant, the blood can clot, producing serum, and the gel barrier stabilizes the sample for downstream chemistry and serology tests. That combination—serum-producing without anticoagulant plus a gel barrier—makes this tube the best fit for chemistry panels and serology.

Other tubes don’t fit this need because they contain additives that prevent clotting (gray with fluoride/oxalate, lavender with EDTA) or lack a gel barrier (red top without a gel).