What is the primary function of a serum separator tube (SST)?

The primary function of a serum separator tube (SST) is to separate blood cells from serum. SSTs are designed with a gel that forms a barrier between the serum and the cellular components of blood once the sample has been processed. When a blood sample is collected in an SST, it is usually left to clot, and then it is centrifuged. During centrifugation, the heavier blood cells settle at the bottom of the tube, while the lighter serum rises to the top and forms a distinct layer above the gel barrier. This separation allows for the easy collection of serum for various laboratory tests without contamination from the cellular elements, making SSTs extremely valuable for diagnostic purposes. The efficient separation of serum is crucial for numerous biochemical tests where serum is required, ensuring accurate results and reliable patient diagnostics.