Which Tube for Which Test?
The tube color and additive for the tests phlebotomy students are asked about most, checked against the BD order-of-draw chart and the CLSI PRE02-Ed8 venous collection standard, and the ARUP Laboratories test directory. Tap a test for handling details and exam tips.
| Test | Tube |
|---|---|
| CBC (complete blood count) | Lavender-top K2EDTA tube (pink K2EDTA is also accepted). |
| PT/INR (prothrombin time) | Light blue-top tube with 3.2% sodium citrate, filled to the line. |
| Hemoglobin A1c | Lavender-top (or pink) K2EDTA tube; the test uses whole blood. |
| Lipid panel | Serum separator tube (gold) or a plasma separator tube (light green), depending on the lab. |
| BMP / CMP (basic or comprehensive metabolic panel) | Gold-top SST or light green-top PST (lithium heparin). |
| Glucose (fasting) | Gray-top tube (sodium fluoride / potassium oxalate). SST or PST are also accepted if separated promptly. |
| Blood culture | Aerobic and anaerobic blood culture bottles, always drawn first. |
| Ammonia | Varies by lab: many hospitals use a green-top heparin tube; ARUP asks for EDTA. Always on ice. |
| Lactate (lactic acid) | Pre-chilled gray-top tube (sodium fluoride / potassium oxalate), on ice. |
| Type and screen / crossmatch | Pink-top (or lavender) K2EDTA tube, labeled to blood-bank rules. |
| aPTT | Light blue 3.2% sodium citrate, filled to the line |
| D-dimer | Light blue 3.2% sodium citrate |
| TSH | PST (light green) or SST (gold) |
| Troponin | Green lithium heparin or PST; some troponin I assays accept serum (assay-dependent) |
| ESR | Lavender EDTA at many labs; some use a citrate (black-top) Westergren tube; results are not interchangeable |
| Blood lead | Royal blue K2EDTA trace-element tube (tan K2EDTA also exists) |
| Potassium / magnesium | SST or PST; hemolysis falsely raises both |
Order of draw and inversions
- 1. Blood culture bottles (aerobic + anaerobic) (Culture media): invert Per bottle instructions
- 2. Light blue (3.2% sodium citrate): invert 3–4 times
- 3. Gold / red-gray (SST) or red (Clot activator (SST also has gel)): invert 5 times
- 4. Green / light green (PST) (Lithium heparin (PST also has gel)): invert 8–10 times
- 5. Lavender (or pink) (K2EDTA): invert 8–10 times
- 6. Gray (Sodium fluoride / potassium oxalate): invert 8–10 times
With a butterfly set, if a light blue citrate tube is first, draw a discard tube before it. More in the order of draw guide.
Want it on paper? Print the one-page tube color and additives cheat sheet or the order of draw chart (free PDFs).
Tube requirements differ between labs and assays. Always follow your own laboratory's collection manual.
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