What is what color tubes are used for which tests in phlebotomy?

Here's a breakdown of common blood collection tubes and their uses in phlebotomy:

• Light Blue Top: Contains sodium citrate as an anticoagulant. Primarily used for coagulation studies like PT (Prothrombin Time), PTT (Partial Thromboplastin Time), fibrinogen, and D-dimer tests. It is crucial that these tubes are filled completely to ensure the correct blood-to-anticoagulant ratio for accurate results.

• Red Top: Contains no anticoagulant or additives (or may contain clot activators). Blood clots naturally in these tubes. Used for serum-based tests in chemistry, serology, and some immunology tests. Examples include: Basic Metabolic Panel (BMP), Comprehensive Metabolic Panel (CMP), lipid panel, and therapeutic drug monitoring.

• Gold Top (or Serum Separator Tube - SST): Contains a clot activator and a gel separator. After centrifugation, the gel forms a barrier between the serum and blood cells, allowing for easier serum separation. Used for various chemistry tests, immunology tests, and some serology tests where serum is required.

• Green Top: Contains heparin (either lithium heparin, sodium heparin, or ammonium heparin) as an anticoagulant. Used for plasma-based chemistry tests, such as ammonia levels, and some specialized assays. Lithium heparin is the most common type.

• Lavender/Purple Top: Contains EDTA (ethylenediaminetetraacetic acid) as an anticoagulant. Primarily used for hematology tests, such as complete blood count (CBC), erythrocyte sedimentation rate (ESR), and hemoglobin A1c (HbA1c). EDTA binds calcium, preventing blood from clotting.

• Gray Top: Contains sodium fluoride (a glucose preservative) and potassium oxalate (an anticoagulant). Used primarily for glucose testing (especially when a delay in testing is anticipated) and lactate (lactic acid) measurements.

• Yellow Top (ACD or SPS): There are two types of yellow top tubes:

  • ACD (Acid Citrate Dextrose): Used for blood bank studies, HLA phenotyping, and DNA studies.
  • SPS (Sodium Polyanethol Sulfonate): Used for blood cultures to inhibit complement and phagocytosis.

• Pink Top: Contains EDTA. Specifically used for blood bank collections; ensures proper identification.