Free Hemoglobin and Oxyhemoglobin Panel, Plasma
This panel measures free hemoglobin and oxygenated hemoglobin (oxyhemoglobin) in plasma. It can help evaluate the breakdown of red blood cells and possible hemolysis.
["Abnormal results may indicate red blood cell breakdown but must be interpreted with other laboratory findings and the clinical situation."]
Key facts at a glance
- LOINC
- 87433-9
- Short code
- Hgb Free + OxyHgb Pnl Plas
- Synonyms
- Hgb Free + OxyHgb Pnl Plas
- Category
- hematology
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 12
- Ref high
- 17.5
- Critical range
- 7 N/A – 20 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 85018
- SNOMED
- 900000000000003004
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
What the Test Measures
Free hemoglobin is hemoglobin released from red blood cells into the plasma. Oxyhemoglobin is the oxygen-carrying form of hemoglobin; measuring it can help characterize hemoglobin present outside red blood cells.
Why It May Be Ordered
This test may be ordered when there is concern about rapid red blood cell breakdown, including possible intravascular hemolysis. It may also be used when evaluating suspected transfusion reactions or other complications of hemolysis.
Why Plasma Is Tested
The specimen is plasma, the liquid portion of blood after cells have been removed. This differs from a standard blood count, which measures hemoglobin inside red blood cells. Small amounts of free hemoglobin may enter plasma during specimen collection or processing.
Factors That Can Affect Results
Drawing blood too forcefully, delayed specimen processing, and other collection or handling issues can cause red blood cells to break open and falsely elevate free hemoglobin. Recent blood transfusions may also affect interpretation.
Reference range
Adult males: 13.5-17.5 g/dL; Females: 12.0-16.0 g/dLN/A
No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical significance: Elevated free plasma hemoglobin may support a diagnosis of intravascular hemolysis, the destruction of red blood cells within the circulation. Results should be interpreted by a clinician alongside symptoms, other blood tests, and specimen-quality information because handling-related cell breakdown and recent transfusion can also influence the results.
Short name
Free hemoglobin/oxyhemoglobin panel
Frequently asked questions
Does this test replace a complete blood count?
Possible causes include significant red blood cell breakdown, hemolysis after a transfusion, and red blood cell damage caused during blood collection or specimen processing. The clinical context is important.
No. It can support the presence of red blood cell breakdown, but additional tests are usually needed to identify its cause and assess effects on organs and blood cells.
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy