A serum-separating tube or serum separator tube (SST) is a

test tube A test tube, also known as a culture tube or sample tube, is a common piece of laboratory glassware consisting of a finger-like length of glass or clear plastic tubing, open at the top and closed at the bottom. Test tubes are usually placed in s ...

used in clinical chemistry tests requiring

blood Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood is com ...

serum Serum may refer to: Biology and pharmacology *Serum (blood), plasma from which the clotting proteins have been removed **Antiserum, blood serum with specific antibodies for passive immunity *Serous fluid, any clear bodily fluid Places *Serum, Ind ...

. SSTs are sometimes called "gold-topped tubes", "tiger-tops", or "marble-top tubes", referring to the colored stoppers which are either gold, red with a gold ring on top, or marbled red and grey. Stoppers on SPS (sodium polyanethol sulfonate) tubes have a paler yellow color, sometimes causing confusion; these are known as "yellow tops", not "gold". Trademarked versions of the SST include

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"Corvac" tubes.

Features

The tubes have micronized silica particles which help clot the blood before centrifugation, and a gel at the bottom which separates whole blood cells from serum. Silica

nanoparticle A nanoparticle or ultrafine particle is a particle of matter 1 to 100 nanometres (nm) in diameter. The term is sometimes used for larger particles, up to 500 nm, or fibers and tubes that are less than 100 nm in only two directions. At ...

s induce coagulation through contact activation of

coagulation factor XII Coagulation factor XII, also known as Hageman factor, is a plasma protein involved in coagulation. It is the zymogen form of factor XIIa (), an enzyme of the serine protease (or serine endopeptidase) class. In humans, factor XII is encoded by ' ...

(Hageman factor). The silica particles are desiccants, which adsorb and hold water vapor. This is used in the tubes so the blood adheres to the surface of the tiny silica particles and begins to clot. After the blood sample is centrifuged, the clear serum should be removed for testing.

Use

These tubes should be used with care when measuring

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or hormone levels because the drug or hormone may diffuse from the serum into the gel, causing a reduction in measured level. The gel in SST II tubes (which appears slightly less opaque) is supposed to have less effect on drug levels in serum. Blood samples should be allowed time to form a clot at room temperature for 30–60 min. CDC recommends a range of time to allow clot formation that was reasonably consistent, from a minimum of 30 min to 60 min maximum.

References

{{DEFAULTSORT:Serum-Separating Tube Laboratory equipment

Features

Use

See also

References