Centrifugation Settings for Blood and Urine Specimens
For routine clinical chemistry, hematology, and immunology blood samples, centrifuge at 1500-2000 × g for 10 minutes at room temperature or 4°C, while urine samples require lower speeds of approximately 400-500 × g for 5-10 minutes.
Blood Specimen Centrifugation
Standard Protocol for Serum and Plasma
The most widely recommended approach is centrifugation at 1500-2000 × g for 10 minutes, which ensures adequate separation while minimizing hemolysis and cellular contamination 1. This protocol applies to:
- Chemistry panels: Standard biochemistry analytes are stable at these settings 1
- Immunology testing: Antibody and protein measurements require platelet-poor plasma, achieved with this centrifugation force 1
- Hematology applications: When plasma is needed for coagulation studies or other hematologic assays 1
Temperature Considerations
- Centrifuge at room temperature or 4°C for most applications 1
- Most biomarkers show no significant difference between room temperature and 4°C centrifugation, with the exception of tau protein which may be lower at 4°C 1
- Avoid temperature extremes that could cause hemolysis or protein precipitation 1
Alternative High-Speed Protocols
For urgent situations requiring faster turnaround time, you can safely use 3000 × g for 5-7 minutes without compromising analytical quality for most analytes 2, 3. However, important caveats include:
- Lactate dehydrogenase (LDH) may be falsely elevated with higher centrifugation speeds due to increased cellular disruption 2, 3
- This shortened protocol has been validated for prothrombin time, activated partial thromboplastin time, and fibrinogen 4, 5
- Ultra-high speed (11,000 × g for 2 minutes) can be used for coagulation testing specifically, showing excellent correlation with standard methods 4
Specialized Applications
For platelet-rich plasma (PRP) preparation, use significantly lower speeds of 170-200 × g for 10 minutes to preserve platelet integrity 6, 7. This is critical for regenerative medicine applications where platelet function must be maintained.
For platelet-poor plasma required in coagulation studies, use two sequential centrifugations at 2500 × g for 15 minutes each to adequately remove platelets and prevent spurious results 1. The International Society on Thrombosis and Haemostasis specifically recommends this double-spin approach 1.
For RBC isolation in hematology research, density-gradient centrifugation at 2500 RPM for 15 minutes at room temperature provides pure red blood cell suspensions 1.
Urine Specimen Centrifugation
Urine samples require gentler centrifugation at approximately 400-500 × g for 5-10 minutes to sediment cellular elements and casts without disrupting formed elements. While the provided evidence does not contain specific urine centrifugation guidelines, standard clinical laboratory practice uses lower speeds than blood to preserve cellular morphology for microscopic examination.
Critical Pitfalls to Avoid
- Never use excessive centrifugation speed or duration, as this causes hemolysis and falsely elevates intracellular components like potassium, LDH, and AST 1
- Avoid insufficient centrifugation, which leaves residual platelets and cells that can interfere with assays 1
- Do not collect the last 0.5 cm of plasma above the buffy coat to minimize cellular contamination 1
- Set the centrifuge to the lowest deceleration setting to prevent resuspension of the cellular layer 1
- Process blood within 2 hours of collection (or refrigerate at 4°C for up to 24 hours maximum) to prevent biomarker degradation 1
Tube-Specific Considerations
- Serum tubes (red top, SST) require 10 minutes at 1500-2000 × g after 30-60 minutes clotting time 1
- Plasma tubes (EDTA, heparin, citrate) should be centrifuged within 2 hours at 1500-2000 × g for 10 minutes 1
- Gel separator tubes may tolerate slightly higher speeds, but maintain consistency within studies 1