EDTA plasma is the liquid component of blood obtained after specific processing.
Obtaining EDTA Plasma
To understand what EDTA plasma is, let's break down the process:
- Blood Collection: Blood is collected into a lavender (purple) top tube. These tubes contain the anticoagulant EDTA (ethylenediaminetetraacetic acid).
- Centrifugation: The collected blood sample is then centrifuged. This process spins the blood at a high speed, separating its components.
- Plasma Separation: After centrifugation, the blood separates into layers. The topmost layer, a clear fluid, is the plasma. This plasma is then carefully removed.
- Labeling: This removed plasma must be correctly labeled with the owner's name, animal ID, and the words "EDTA plasma" to ensure proper identification.
Key Points about EDTA Plasma:
- Anticoagulant: The presence of EDTA in the collection tube prevents blood from clotting by binding to calcium ions, which are essential for the coagulation process.
- Supernatant: EDTA plasma is referred to as the "supernatant" because it is the liquid that remains above the settled cellular components after centrifugation.
- Specific Tests: EDTA plasma is specifically required for certain diagnostic tests, such as those for ACTH (adrenocorticotropic hormone) and insulin levels.
Why Use EDTA Plasma?
EDTA plasma is crucial for certain tests because:
- Preserves Blood Components: EDTA helps to preserve the blood's components in their natural state, ensuring that test results are accurate.
- Prevents Clotting: Preventing clotting allows for the isolation of plasma without the consumption of coagulation factors or the formation of fibrin that would interfere with many assays.
EDTA Plasma in Diagnostic Testing
Here is an overview of the diagnostic tests that often require EDTA plasma:
| Test | Relevance |
|---|---|
| ACTH Endogenous | Measures the body's natural production of ACTH. |
| ACTH & Insulin | Determines the level of both ACTH and insulin in the blood simultaneously. |
Example
For example, if a veterinarian needs to measure the endogenous ACTH levels in an animal, they would collect a blood sample in a lavender top tube, centrifuge it, and then use the resulting EDTA plasma for the test.
