Lab Tube Cheat Sheet
Which tube for which test, the two reference labs' different urine containers, and the timing rule for vancomycin troughs.
Draw the wrong tube and the patient gets stuck twice. Keep this one on your phone.
When in doubt, draw a serum separator. Most tests we send run off an SST.
By test
| Tube | Tests |
|---|---|
| Serum separator (SST) | BMP, CMP, electrolytes, renal function panel, liver function panel, ferritin, vitamin B12, iron/total, AST, ALT, CRP, CK, FSH, magnesium, phosphorus, potassium, triglycerides, TSH / free T4, BUN |
| Blue top (sodium citrate) | PT/INR, PTT |
| Lavender top (EDTA) | Hgb A1c, hemoglobin, hematocrit, CBC with differential, sed rate |
| Heparin — lithium or sodium | Vancomycin trough |
The vancomycin trough goes in a separate tube from everything else. Do not combine it with the lavender-top draw.
Vancomycin trough timing
Draw the trough 30 minutes to one hour before the next antibiotic dose is administered.
A trough drawn at the wrong time is not a slightly-off result, it is an uninterpretable one — and the dose gets adjusted off it anyway unless someone catches the timing. Write the exact draw time and the scheduled dose time in your note.
Urine cultures — the two labs differ
This is the one people get wrong most often, because it depends on where the specimen is going.
| Lab | Urine culture container |
|---|---|
| Saint Luke's | Grey top |
| Quest | UriSponge |
Other urine collection
| Lab | Containers |
|---|---|
| Quest | Yellow-top preservative tube with a blue fill line; yellow/red swirl-topped conical transport tube with preservative; or 3 mL unpreserved urine cup |
| Saint Luke's | Tiger top |
Before you leave the home
- Right tube for the test, and the right container for the receiving lab
- Tubes labelled at the bedside — never in the car
- Draw time recorded, and for troughs, the next dose time as well
- Requisition matches what you actually drew
- Specimen transported per policy — see Transporting Lab Specimens
- Results follow-up planned — who is chasing the result, and when