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🩸 Lab Tube Color Reference Guide

Complete reference for blood collection tube colors, additives, draw order, and nursing considerations. Essential guide for accurate specimen collection and patient safety.

🩸 Complete Order of Draw

1st: Blood Cultures

Royal Blue follows the additive (serum/EDTA/heparin), not the cap color.

Note: Serum tubes (red or gold/SST) come before heparin tubes. Heparin tubes (green and light-green/PST) precede EDTA, then gray. Some facilities set a sub-order within serum/heparin; follow your lab's policy.

Educational Use Only: Always follow your facility's specific protocols and current guidelines.

🩸 Master Lab Draws with This Essential Reference

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Lab Draw Badge Card

Essential phlebotomy reference with tube colors, draw order, and lab values - everything you need for successful lab draws.

Lab Values Tube Colors Draw Order
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Additive
3.2% Sodium Citrate
Critical Ratio
9:1 Blood:Citrate
Fill Level
90% Full (Critical!)
Process Within
Per facility policy
  • Prothrombin Time (PT/INR) - Warfarin monitoring
  • Activated Partial Thromboplastin Time (PTT) - Heparin monitoring
  • D-dimer - DVT/PE screening
  • Fibrinogen levels
  • Factor assays (VIII, IX, etc.)
  • Anti-Xa levels
  • 90% Fill Rule: Underfilled tubes yield falsely prolonged results
  • Draw Order: Second tube after blood cultures (prevents contamination)
  • Butterfly Sets: When using a butterfly and the first tube is light blue, use a discard tube to clear the air-space
  • Gentle Mixing: 3-4 inversions immediately post-draw
  • Processing: Process per facility policy; many labs require aPTT within 4 hours of collection. Verify your lab's window
Additive
None (Plain)
Specimen Type
Serum
Clotting Time
15-30 min
Mixing
Glass plain red: no inversion; Plastic red (clot activator): invert 5x
  • Therapeutic drug levels (Digoxin, Phenytoin)
  • Hormone panels (TSH, Cortisol)
  • Immunology markers
  • Serology testing
  • Tumor markers
  • Processing: Allow complete clotting before centrifugation
  • Temperature: Room temperature during clotting phase
  • Anticoagulants: May extend clotting time significantly
  • Hemolysis Risk: Gentle handling during transport essential
Additive
Clot activator + Gel
Specimen Type
Serum
Inversions
5-6 times
Centrifuge
Required
  • Basic Metabolic Panel (BMP) - Na, K, Cl, CO2, BUN, Creatinine, Glucose
  • Comprehensive Metabolic Panel (CMP) - includes liver enzymes
  • Lipid profiles - Total cholesterol, HDL, LDL, Triglycerides
  • Cardiac markers - Troponin I/T, CK-MB (per lab test directory)
  • Thyroid function - TSH, Free T4

The gel barrier forms during centrifugation, creating a stable separation between serum and cellular components. This allows serum to be aspirated without cellular contamination and maintains specimen integrity for extended periods.

  • Immediate mixing: Gentle inversion prevents microclots
  • Fill volume: Adequate blood volume ensures proper gel function
  • Storage: Post-separation storage per test directory; stability varies by analyte and lab policy
  • Avoid: Vigorous shaking can cause hemolysis
Additive Options
Na or Li Heparin
Specimen
Plasma
Inversions
8-10 times
Processing
Immediate
  • Arterial Blood Gases (ABGs) - pH, pCO2, pO2 (Collected in heparinized syringe; see ABG policy)
  • STAT electrolyte panels
  • Ionized calcium (Specimen type per lab method; many require heparinized whole blood syringe or specific tubes)
  • Ammonia levels (special handling required)
  • Emergency chemistry panels

Note: ABGs are typically collected in heparinized syringes, not vacutainers; some labs may process lithium-heparin plasma for related chemistry but not for arterial blood gases.

  • Lithium Heparin: General chemistry/STAT; avoid for lithium levels
  • Sodium Heparin: Niche/specific methods per lab
  • PST (Plasma Separator): Contains gel barrier
Additive
Li Heparin + Gel
Specimen
Plasma
Inversions
8-10 times
Advantages
Gel Barrier
  • STAT chemistry panels
  • Basic metabolic panels (rapid)
  • Cardiac markers (emergency) (per lab test directory)
  • Therapeutic drug monitoring
  • Point-of-care testing compatibility
  • Faster processing: No clotting time required
  • Gel separation: Clean plasma layer post-centrifuge
  • Stability: Plasma stable on gel barrier
  • Emergency use: Ideal for STAT chemistry
Additive
K₂ or K₃ EDTA
Cell Preservation
Excellent
Stability
Best within 24h; per lab policy
Inversions
8-10 times
  • Complete Blood Count (CBC) with differential
  • Hemoglobin and Hematocrit (H&H)
  • Platelet count and morphology
  • Reticulocyte count
  • Hemoglobin A1c
  • ESR (Erythrocyte Sedimentation Rate) (lab-method dependent)
  • EDTA-dependent clumping: Can affect platelet counts
  • Proper fill: Maintains correct blood-to-anticoagulant ratio
  • Room temperature: Best storage for cell morphology
  • Immediate mixing: Prevents microclot formation
Additive
EDTA (K₂)
Patient ID
Bedside Verification
Chain of Custody
Strict Protocol
Storage
Transport promptly per blood bank policy
  • ABO/Rh blood typing
  • Antibody screening and identification
  • Crossmatching for transfusions
  • Direct antiglobulin test (DAT/Coombs)
  • Prenatal antibody screening
  • Follow your facility/AABB policy for: Two identifiers (Name + DOB or medical record number)
  • Bedside labeling: Must label in patient's presence per facility protocol
  • Verbal confirmation: Patient states name and DOB
  • Documentation: Note collection time and staff signature
  • Storage/retention: Per facility protocol (storage/retention policies vary by institution)
Additive
Fluoride/Oxalate
Draw Order
Last for Chemistry
Glucose Stability
Per lab policy (prompt separation)
Inversions
8-10 times
  • Fasting blood glucose (FBG)
  • Oral glucose tolerance test (OGTT)
  • 2-hour post-prandial glucose
  • Lactate levels
  • Blood alcohol content (forensic)

Glycolysis Prevention: Without fluoride, red blood cells continue consuming glucose at ~5-7% per hour at room temperature. Sodium fluoride inhibits enolase enzyme, stopping glycolysis and preserving true glucose levels.

Important: Royal blue tubes come as serum (red band), EDTA (lavender band), or heparin (green band). Follow the order based on the additive, not just the cap color. See Mayo Clinic Laboratories trace-metals collection instructions for trace-metal handling.

Manufacturing
Clean Room
Contamination
Metal-Free
Needle Type
Stainless/Plastic
Applications
Heavy Metals
  • Lead, Mercury, Arsenic levels
  • Zinc, Copper, Selenium
  • Aluminum (dialysis monitoring)
  • Chromium, Manganese
  • Micronutrient analysis

⚠️ Specialty Collection Tubes

Yellow Top (ACD): Used for DNA/paternity testing and HLA typing. Not part of standard draw order - collected separately when specifically ordered and follows site policy.

Black Top (ESR): Contains sodium citrate 4:1 ratio for erythrocyte sedimentation rate testing. Follows citrate logic for timing and handling.

Note: Other specialty tubes (e.g., trace metal-free, viral transport) have facility-specific protocols and are not included in standard phlebotomy training.

🔧 Quick Troubleshooting & Pro Tips

Hemolyzed Specimen

Causes: Too small needle, excessive suction, rough handling
Prevention: 21-22G needle, gentle technique, immediate gentle mixing
Impact: Falsely ↑ K+, LDH, AST

Underfilled Coag Tube

Problem: Falsely prolonged PT/PTT times
Solution: Ensure 90% fill, use butterfly for difficult draws
Critical: 9:1 blood-to-citrate ratio essential

EDTA Platelet Clumping

Recognition: Falsely low platelet count
Solution: Collect in citrate tube for manual count
Note: Affects ~1% of population

ABG Collection Tips

Air bubbles: Remove immediately, affects O2/CO2
Ice: Ice slurry if analysis delayed >30 min (per lab/analyzer policy)
Heparin: Just coat syringe, excess dilutes sample

📚 Memory Aids & Study Tips

Color Memory Tricks

  • Red: "Red for Rest" (clotting time needed)
  • Blue: "Blue for Bruising" (coagulation)
  • Purple: "Purple for People counting" (CBC)
  • Green: "Green for Go fast" (STAT plasma tests)

Critical Numbers

  • Blue tubes: 90% fill (9:1 ratio)
  • Process coagulation samples within: your lab's validated window (commonly ≤4 hours)
  • Tourniquet time: <60 seconds max
  • Clotting time: 15-30 minutes

Quick Test Categories

  • Chemistry panels: Gold/Red tubes
  • Blood counts: Purple tubes
  • Clotting studies: Light blue tubes
  • Blood typing: Pink tubes

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📚 References & Sources ▼

Click to view references

⚠️ Important Disclaimer

Educational Use Only: Always follow your facility's specific protocols and current institutional guidelines. When in doubt, consult laboratory personnel or supervisory staff. Procedures may vary by institution and patient population.

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