Serum-separating tubes, also known as serum separator tubes or SSTs, are used in
clinical chemistry
Clinical chemistry (also known as chemical pathology, clinical biochemistry or medical biochemistry) is the area of chemistry that is generally concerned with analysis of bodily fluids for diagnostic and therapeutic purposes. It is an applied ...
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 in the cir ...
serum.
SSTs are sometimes called "marble-top tubes", "tiger-tops", or "gold-topped tubes", referring to the stoppers which are either gold, red with a gold ring on top, or marbled red and grey. Marble-top tubes are also referred to as "tiger-tops" in some clinics. The stopper of SPS (sodium polyanethol sulfonate) tubes have a paler yellow colour, sometimes causing confusion; these are known as "yellow tops" not "gold". Trademarked versions of the SST include
Covidien "Corvac" tubes.
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 nanoparticles induce coagulation through contact activation of Hageman factor XII. 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.
These tubes should be used with care when measuring
drug 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.
See also
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Vacutainer
A vacutainer blood collection tube is a Sterilization (microbiology), sterile glass or plastic test tube with a colored rubber stopper creating a vacuum seal inside of the tube, facilitating the drawing of a predetermined volume of liquid. Vacut ...
*
Venipuncture
In medicine, venipuncture or venepuncture is the process of obtaining intravenous access for the purpose of venous blood sampling (also called ''phlebotomy'') or intravenous therapy. In healthcare, this procedure is performed by medical labor ...
References
{{DEFAULTSORT:Serum-Separating Tube
Laboratory equipment