I guess its my inner OCD coming out, but I’ve always been fascinated with Vacutainer blood collection tubes and their color coding system. I find it to be very organized and uniform and orderly and all these great, efficient things. The rainbow of tubes may be fun to look at, but do you know what each color means? Or why certain lab tests are done in certain color tubes? Below I’ve broken down most of the colors that are manufactured by the most ubiquitous company, BD. Every laboratory facility is different and blood-draw protocol varies widely, but what follows is only what I am familiar with at my specific facility.
(In recommended order of draw)
Light Blue Top - Coagulation panels (PT/INR, PTT, Fibrinogen, Platelet assays)
Glass anti-coagulation tube - Contains a 3.5% sodium citrate solution which forms calcium salts in the blood, removing calcium ions and disrupting the clotting mechanism. These tubes can also be “CTAD” tubes, which contain sodium citrate, theophylline, adenosine and dipyridamol. The last three substances inhibit thrombocyte activation preventing artificial thrombocyte factors from coming into contact with the plasma and interfering with platelet factor assays.
Gold Top - Routine blood chemistry (Chem-7, metabolic panel, cholesterol) & endocrinology
Plastic serum separator tube - Contains a silica clot activator and a polymer gel, and is coated with silicone. The silicone coating prevents RBC’s from adhering to the wall of the tube. The clot activator accelerates the clotting of cells and fibrinogens to 30 minutes, and with the aid of the polymer gel, allows for separation of the blood serum from all other blood components after being centrifuged.
Red & Grey Tiger Top - Infectious disease serology (HIV, Hepatitis, Mononucleosis, VDRL, Rubella)
Plastic serum separator tube - contains the exact same additives as a Gold top tube. My institution uses Red/Grey Tiger tops exclusively for dedicated tube, infectious testing/high priority labs, though these may also be used for routine chemistry.
Red Top - Toxicology, therapeutic drug level monitoring, antibody & immunology
Glass serum tube - NO polymer gel separator or clotting additive. Used for sensitive serum tests where tube additives may interfere with measured levels.
Orange Top - STAT/Emergency Serum tests (Troponin, B-HCG, Creatinine, etc.)
Plastic rapid serum tube - newly marketed as “the speed of plasma, the quality of serum,” this tube contains a thrombin-based clot activator and a polymer separating gel. The blood sample clots in as little as 5 minutes in this tube and the serum can be separated quickly in a centrifuge. Aimed at critical care patients where rapid results mean the difference in care decisions.
Light Green Top - STAT chemistry panel
Plastic plasma separator tube - contains lithium heparin to prevent clotting as well as a polymer separating gel to extract blood plasma after centrifuging. Often used in acute care for a STAT chem-7/electrolyte panel.
Dark Green Top - Plasma testing (ammonia, HLA’s, globins, cytogenetics, amino acids)
Plastic plasma tube - spray coated with sodium heparin to stop thrombin in the coagulation cascade.
Lavender Top - Whole blood hematology (CBC w/Diff, ESR, A1C, platelets,)
Plastic whole blood tube - Spray coated with K(2)-EDTA - Ethylenediaminetetracetic acid. EDTA functions by binding calcium in the blood and keeping the blood from clotting without interfering with whole blood products.
Pink Top - Blood banking (Type & Screen, Crossmatch, Coombs)
Plastic whole blood tube - Contains the same EDTA spray coat as Lavender top, except many institutions have moved towards using this whole blood tube exclusively for the blood bank laboratory. Designed for use with the special pink crossmatch patient information label required by the American Association of Blood Banks.
Pearl White Top - DNA PCR (Adenovirus, Toxoplasma, HHV-6 etc.)
Plastic Plasma Preparation Tube - For use in molecular diagnostic test methods such as polymerase chain reaction [PCR] and/or branched DNA [bDNA] amplification techniques. Contains spray coated K(2) EDTA for cell anticoagulation and a polymer gel for plasma separation.
Grey Top - Lactate & Glucose
Plastic plasma tube - Contains a glycolytic inhibitor, sodium fluoride, to preserve plasma concentrations of lactate and glucose for up to 24 hours until testing can be performed on the sample. Also contains the anticoagulant potassium oxalate, which binds calcium and prevents the clotting mechanism.
Other less-used tubes:
Tan Top - Lead levels
Plastic plasma tube - Contains K(2)-EDTA for anticoagulation and is is certified by the manufacturer to contain less than .01 µg/mL(ppm) lead for accurate and sensitive lead level determinations.
Royal Blue Top - Trace element & nutritional levels (Copper, Zinc, Arsenic, Mercury, etc.)
Plastic serum tube - For trace-element, toxicology, and nutritional-chemistry determinations. The manufacturer certifies the special plastic stopper formulation provides low levels of trace elements which will not interfere with laboratory results.
Yellow Top - Tissue/HLA phenotyping, Flow cytometry, DNA plasmapheresis (paternity testing)
Glass whole blood tube - Known as an ACD-A tube, contains trisodium citrate, citric acid and dextrose in water, which is mainly used as an anticoagulant to preserve blood specimens for sensitive molecular testing and tissue typing.