PRIN_Additives and Order of Draw

• Categories of Additives Used in Blood Collection

  1. Anticoagulants
  2. Special-use anticoagulants
  3. Antiglycolytic Agents
  4. Clot Activators
  5. Thixotropic Gel Separators
  6. Trace Element-Free Tubes
• Anticoagulants (Blood Thinners) - chemical substances that prevent blood clots

  • Methods: by precipitation of calcium and by preventing thrombin formation
  • Types: EDTA, citrates heparin, and oxalates
• Special-Use Anticoagulants

  1. acid citrate dextrose
  2. citrate phosphate dextrose
  3. sodium polyanethol
• Antiglycolytic Agents - substances that prevent the breakdown of glucose by blood cells or glycolysis

  • most common: sodium fluoride which prevents glucose and prevents growth of bacteria; usually with potassium oxalate for rapid response
• Clot Activators - enhance coagulation in serum specimen tubes

  Types of Clot Activators

  1. clotting factors like thrombin
  2. substances providing more surface for platelet activation like glass (silica) particles and inert clays (celite)
• Thixotropic Gel Separator - inhibits cells from metabolizing substances and moves between cells and serum or plasma when centrifuged
• Trace Element-Free Tubes - made of materials that are free of trace element contamination

  • have royal-blue stoppers
  • used for a variety of purposes such as trace element tests, toxicology studies, and nutrient determination
• Commonly used tubes with anticoagulant

  • yellow - SPS (blood culture)
  • lavender - EDTA (CBC/ESR)
  • green - heparin (troponin)
  • light blue - citrate (coagulation PT/APTT)
  • black - oxalate/sodium citrate (ESR)
  • gray - Na fluoride (glucose determination)
• lavender (purple) top

  • two forms: liquid tripotassium (K3EDTA) and spray-coated dipotassium (K2EDTA)
  • must be inverted 8 times
  • anticoagulant of choice for complete blood count and platelet count
  • maintains cellular integrity, inhibit platelet clumping and does not interfere with routine staining procedures
  • must be completely filled to avoid excess EDTA that may shrink the red cells and decrease the hematocrit level, red blood cell indices and erythrocyte sedimentation rate (ESR)
  • cannot be used for coagulation studies because EDTA interferes with factor V and the thrombin-fibrinogen reaction
• pink top - contain spray-coated K2EDTA and are used specifically for blood banking procedures
• white top - contains spray-coated K2EDTA and a separation gel and is called plasma preparation tubes (PPT)

  • NOTE: plasma separator tube contains heparin as anticoagulant
  • used primarily for molecular diagnostics
• light blue top - contain 3.2% or 3.8% sodium citrate

  • required anticoagulant for coagulation studies because it preserves the labile coagulation factors
  • ratio of blood to anticoagulant is CRITICAL and should be 9:1 and hence must be completely filled to ensure accurate results
  • when hematocrit is >55%, the amount of citrate should be DECREASED to prevent an excessive amount of citrate in the plasma
• black top - contains buffered sodium citrate used for Westergren sedimentation rates

  • ratio of blood to anticoagulant 4:1
• green top - contains heparin (sodium, lithium, ammonium)

  • primarily used for chemistry tests particularly those that require Fast TAT
  • must not be used for hematology because heparin interferes with the Wright stained blood smear
  • heparin cause the stain to have a blue background on the blood smear complicating the interpretation of results
• gray top - contains the antiglycolytic agent sodium fluoride

  • NaF preserves glucose for 3 days
  • Interferes with some enzymatic analyses therefore must not be used for chemistry tests
• royal blue top - contains K2EDTA or sodium heparin

  • used for toxicology, trace metal and nutritional analyses
• tan top - used for lead determinations
• yellow top - contains either

  • acid citrate dextrose (ACD) - used for cellular studies in blood bank, HLA phenotyping and DNA and paternity testing
  • sodium polyanethol sulfonate (SPS) - used to collect samples for blood culture to detect microorganisms; inhibits the action of complement, phagocytes and certain antibiotics
• orange top - contains a thrombin-based medical clotting agent

  • called rapid serum tubes (RST)
  • RST clot within 5 minutes
• order of filling evacuated tubes in multiple sampling based on CLSI guidelines:

  1. blood culture bottles or tube (yellow with SPS)
  2. coagulation tube (light blue)
  3. non-additive tube (red with or without clot activators)
  4. heparinized tube (green)
  5. EDTA (purple/lavender)
  6. Na Fluoride (gray)
• CLSI recommended order of draw

  1. Blood cultures (SPS or culture bottles)
  2. Light blue (sodium citrate)
  3. Red/Gray or Gold, Red (glass or plastic)
  4. Green or Light green (heparin, all types)
  5. Lavender (EDTA), pink, or white
  6. Gray (sodium fluoride, potassium oxalate)
  7. Yellow/Gray-Orange (thrombin clot activator)
• glass red top tubes - referred to as plain tubes

  • no anticoagulant or additives
  • number of inversions: 0x
• plastic red top tubes - with additive (clot activator)

  • number of inversions: 5x
• yellow top

  available in three different formulations

  • clot activator/gel separator - no anticoagulant

  contains additive

  • clot activator - hastens clotting process
  • gel separator - separates serum from RBC's and buffy coat