PhlebBot
Tube Colors & Additives
In order of draw. Invert gently the number of times shown, right after collection. Never shake.
| Tube | Additive and what it does | Invert | Common tests | Handling |
|---|---|---|---|---|
| Blood culture bottles (aerobic + anaerobic) | Culture media. Drawn first, so the sample stays sterile. | Per bottle instructions | Blood cultures | Strict skin antisepsis. Butterfly: aerobic bottle first. Adults: about 8–10 mL a bottle. |
| Light blue | 3.2% sodium citrate. Anticoagulant: binds calcium. The plasma keeps its clotting factors. | 3–4 times | PT/INR, aPTT, D‑dimer | Fill to the line (9:1); underfilled tubes are rejected. PT/INR: room temperature. |
| Gold / red-gray (SST) or red | Clot activator (SST also has gel). Silica clot activator makes the blood clot. SST gel separates serum from cells when spun. | 5 times | BMP/CMP, Lipid panel, TSH | Let it clot fully before centrifuging. Glass red: no additive, no inversions. |
| Green / light green (PST) | Lithium heparin (PST also has gel). Anticoagulant: gives plasma, so it can be spun right away (no clotting step). | 8–10 times | STAT chemistry, Troponin, Ammonia (many labs) | Ammonia: on ice at once; spin within about 15 minutes. |
| Lavender (or pink) | K2EDTA. Binds calcium to prevent clotting; whole blood for hematology. | 8–10 times | CBC, Hemoglobin A1c, Type and screen (pink) | Invert right away: clotted CBCs are rejected. Pink (blood bank): label at the bedside. |
| Gray | Sodium fluoride / potassium oxalate. Fluoride stops glycolysis (preserves glucose); oxalate binds calcium. | 8–10 times | Glucose, Lactate, Blood alcohol | Lactate: pre-chilled tube, on ice, separated within 15 minutes. Always drawn last. |
Exam traps
- Hemolysis falsely raises potassium and magnesium; hemolyzed chemistry samples are rejected.
- On ice: ammonia and lactate are the two classic “transport on ice” tests.
- Other tubes: royal blue K2EDTA trace-element tube for blood lead (tan K2EDTA also exists).