Light Green Top Tube (Plasma Separator Tube - PST)

The Light Green Top Tube, also known as the Plasma Separator Tube (PST), is a key player in clinical chemistry testing.

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Its unique design, which includes a lithium heparin anticoagulant and a gel separator, allows for rapid plasma separation and accurate results.

This blog explores the Light Green Top Tube, its components, applications, and best practices, providing a complete guide for laboratory professionals.

What is Light Green Top Tube & How is it Used in Blood Collection?

A Light Green Top Tube is specifically designed to collect blood, prevent clotting, and separate plasma quickly. It contains:

• Lithium Heparin as an anticoagulant – prevents clotting by inhibiting thrombin and clotting factors.
• Gel Separator – forms a barrier between plasma and blood cells during centrifugation.

This tube is primarily used for plasma-based chemistry tests such as electrolyte panels, liver function tests, and cardiac markers. After collection, the tube must be inverted several times to mix the blood with heparin, then centrifuged to separate plasma for analysis.

Science Behind the Light Green Top Tube

Definition: The Light Green Top Tube is a plasma separator tube (PST) containing lithium heparin and a gel barrier to allow fast and efficient plasma separation.

How Does It Work?

1. Draw Blood: Collect blood using standard venipuncture.
2. Mix with Heparin: Gently invert 8-10 times to mix blood with anticoagulant.
3. Centrifuge: Spin the tube; gel rises to form a barrier between plasma and cells.
4. Obtain Plasma: Plasma can be directly aspirated for testing.
5. Analyze: Use separated plasma for chemistry assays.

Importance & Key Features of a Light Green Top Tube

Top 10 Laboratory Tests That Use Light Green Top Tube

1. Electrolyte Panel: Measures sodium, potassium, chloride, bicarbonate.
2. Liver Function Tests (LFT): Includes AST, ALT, ALP, bilirubin.
3. Renal Function Tests: Includes BUN, creatinine.
4. Cardiac Markers: Troponin, CK-MB, BNP.
5. Lipid Profile: Total cholesterol, HDL, LDL, triglycerides.
6. Thyroid Function Tests: TSH, T3, T4.
7. Glucose Testing: Plasma glucose levels for diabetes monitoring.
8. CRP (C-Reactive Protein): Detects inflammation.
9. Hormone Assays: Cortisol, insulin.
10. Therapeutic Drug Monitoring: Plasma levels of certain medications.

Best Practices for Using Light Green Top Tube in Phlebotomy

• Verify Patient Information: Confirm identity and label tube immediately.
• Use Correct Tube: Ensure light green top PST is selected for plasma-based tests.
• Mix Immediately: Gently invert 8-10 times to avoid clotting.
• Centrifuge Promptly: Separate plasma quickly to prevent cellular metabolism from affecting results.
• Avoid Hemolysis: Use correct needle gauge and gentle handling.
• Follow Order of Draw: Collect after serum tubes to avoid cross-contamination.

10 Step-by-Step Guide to Proper Light Green Top Tube Usage

1. Gather Supplies: PST tube, tourniquet, sterile needle, alcohol swabs, gloves.
2. Verify Patient Identity: Use two identifiers and label tube correctly.
3. Prepare Site: Clean venipuncture site and allow to dry.
4. Perform Venipuncture: Insert needle at 15–30° angle.
5. Collect Blood: Fill to indicated volume.
6. Mix Sample: Gently invert 8-10 times.
7. Remove Needle: Apply pressure with gauze.
8. Centrifuge: Spin according to lab protocol to separate plasma.
9. Store Appropriately: Keep plasma refrigerated if not tested immediately.
10. Transport/Process: Deliver to analyzer or lab promptly.

7 Common Mistakes to Avoid When Using Light Green Top Tube

1. Inadequate Mixing: Leads to clotting and unusable plasma.
2. Delayed Centrifugation: Causes metabolic changes affecting test results.
3. Wrong Tube Selection: Using serum tubes instead of PST can delay results.
4. Hemolysis: Rough handling can release intracellular components.
5. Underfilling Tube: Affects blood-to-additive ratio.
6. Incorrect Storage: Plasma degradation if left at room temperature too long.
7. Improper Order of Draw: May cause additive carryover and interfere with tests.

5 Innovations and Advances in Blood Collection: Future of Light Green Top Tube

1. Faster Gel Separation: Advanced gels that allow shorter centrifuge times.
2. Improved Heparin Formulations: Minimize interference with sensitive assays.
3. Micro-Collection PST Tubes: For pediatric or low-volume samples.
4. Pre-Analytical Automation: Robotic centrifugation and transport systems.
5. Integrated Tracking: RFID-enabled tubes for better workflow management.

FAQs: Light Green Top Tube

1. What is the Light Green Top Tube used for?
For plasma-based chemistry tests, especially when rapid turnaround is needed.

2. Why is lithium heparin used?
It prevents clotting quickly, allowing for immediate plasma separation.

3. Can this tube be used for coagulation studies?
No, coagulation studies require light blue top (sodium citrate) tubes.

4. How soon should plasma be separated?
Ideally within 2 hours of collection to maintain accuracy.

5. Can the tube be frozen?
Plasma can be frozen after separation if long-term storage is needed.

6. What happens if the tube is not mixed properly?
Clots may form, rendering the sample unusable.

7. What is the main advantage of PST tubes?
They save time by eliminating clotting wait time required for serum tubes.

Drlogy Blood Collection Tube Guide

Here are 14 types of blood collection tubes with color.

Conclusion

The Light Green Top Tube (PST) is essential for rapid and accurate plasma-based testing. Its lithium heparin anticoagulant and gel barrier enable quick plasma separation, improving turnaround time and diagnostic efficiency. Proper handling, timely centrifugation, and adherence to best practices ensure reliable and clinically meaningful results.

Check Complete Guide on Drlogy Blood Collection Tubes with Color Codes & Uses to master phlebotomy techniques, improve sample handling, and reduce pre-analytical errors.