Lavender top tube
Additive: anticoagulant EDTA (ethylenediaminetetraacetic acid). EDTA slows down/ stops coagulation by binding to calcium in the specimen. Fill tubes at least 2/3 full & invert 8 times.
Common tests: hematology tests on whole blood. CBC (Complete Blood Count); RBC count, WBC count & platelet count; WBC differential count; Hemoglobin & Hematocrit determinations; ESR (erythrocyte sedimentation rate); sickle cell screening
Light-Blue top tube
Additive: anticoagulant sodium citrate (prevents coagulation by binding to calcium in the specimen). Fill tubes completely to maintain the ratio of 9 parts blood to 1 part sodium citrate. Invert tubes 3 - 4 times.
Common tests: Coagulation tests on plasma - PT (Prothrombin Time - evaluates the extrinsic
system of the coagulation cascade & monitors coumadin therapy); APTT/ PTT (Activated Partial Thromboplastin Time - evaluates the intrinsic system of the coagulation cascade & monitors heparin therapy); FDP (Fibrinogen Degradation Products); TT (Thrombin Time); Factor assays; BT (Bleeding Time)
Green top tube
Additive: sodium heparin, lithium heparin, ammonium heparin. Heparin slows down/ stops thrombin in the coagulation cascade. It's not used for hematology because heparin interferes with the Wright's stained blood smear. Invert tube 8 times.
Common tests: chemistry tests on plasma: ammonia, carboxyhemoglobin & STAT electrolytes, chromosome screening
Gray top tube
Additive: All top tubes contain a glucose preservative (antiglycolytic agent): sodium fluoride (preserves glucose for 3 days) or lithium iodoacetate (preserves glucose for 24 hours). May also contain the anticoagulant potassium oxalate (prevents clotting by binding calcium). Invert 8 times.
Common tests: Fasting blood sugar (FBS); Glucose tolerance test (GTT); Blood alcohol levels; Lactic acid measurement
Red/Gray (speckled) top tube - tiger-top tube and serum separator tubes (SST)
Additive: clot activators - glass particles, silica and celite (speeds up clot formation) & thixotropic gel (a serum separator which when centrifuged forms a barrier between the serum & the cells preventing contamination of the serum with cellular elements). Must be inverted 5 times.
Common laboratory use: chemistry tests on serum (glucose, cholesterol, triglycerides, potassium)
Red top tube (plain vacuum tube)
Additive: no additive or anticoagulant. Collected blood clots by normal coagulation process in 30 minutes; no need to invert the tube after collection.
Common tests: Serum chemistry tests (glucose, cholesterol, triglycerides, HDL, potassium, amylase, alkaline phosphatase, BUN, CK, liver enzymes); Serology tests (RPR, monospot, rheumatoid factor, ANA); blood bank
Yellow top tube (sterile)
Additive: anticoagulant SPS (sodium polyanethol sulfonate) & ACD (acid citrate dextrose)
Common tests: tubes with SPS - for blood cultures. The SPS aids in the recovery of microorganisms by slowing down/ stopping the actions of complement, phagocytes, and certain antibiotics. These tubes should be inverted 8 times. Tubes with ACD are for cellular studies, HLA typing, paternity testing.
Light-green or green/ gray Plasma separator tube
Additive: lithium heparin & gel for plasma separation
Common laboratory use: plasma tests in chemistry department, STAT chemistry tests
Additive: clot activator (plastic serum), EDTA (plastic)
Common laboratory use: for trace elements, toxicology, and nutritional chemistry testing