For creatinine testing, blood can be collected in a few different types of tubes, according to Labcorp guidelines.
Based on the reference provided by Labcorp, creatinine testing can be performed using blood collected in the following tube types:
- Red-top tube: This tube typically contains no additive and is used for collecting serum.
- Gel-barrier tube: This tube contains a gel that separates serum or plasma from blood cells after centrifugation. These often have different colored tops like gold or red/gray mottled, but are functionally defined by the gel barrier.
- Green-top (lithium heparin) tube: This tube contains lithium heparin, an anticoagulant, and is used for collecting plasma.
Important Considerations:
It's crucial to use the correct tube type as specified by the laboratory performing the test. The reference also specifically states which tubes should not be used:
- Oxalate plasma
- EDTA plasma
- Citrate plasma
Different tube types (like those with heparin, EDTA, oxalate, or citrate) contain different anticoagulants or additives which can interfere with specific lab assays if not appropriate for the test being ordered. Using a red-top or gel-barrier tube yields serum (blood liquid portion after clotting), while a green-top (lithium heparin) tube yields plasma (blood liquid portion prevented from clotting). Both serum and heparinized plasma are acceptable for creatinine testing according to the provided source.
Here's a summary of the acceptable tubes:
| Tube Type | Color Top (Common) | Sample Type |
|---|---|---|
| Red-top tube | Red | Serum |
| Gel-barrier tube | Gold, Red/Gray | Serum or Plasma |
| Green-top (lithium heparin) | Green | Plasma |
Following the specific instructions from the laboratory or healthcare provider regarding the correct tube type is essential for accurate test results.
