Overview
Plasma hemoglobin quantifies hemoglobin released into plasma when RBCs lyse in the vascular space (or during sample collection artifact).
Clinical Importance
To support diagnosis of intravascular hemolysis
To monitor hemolysis in ECMO, ventricular assist devices, and similar circuits when protocolized
Specimen Requirements
- Atraumatic draw; avoid hemolysis during collection
- EDTA or heparin plasma per method; centrifuge promptly and separate plasma
- Protect from further mechanical hemolysis; follow laboratory transport rules
- Do not use hemolyzed chemistry samples as substitutes without method validation
Analytical Method
Spectrophotometric methods measure plasma hemoglobin using absorbance characteristics of hemoglobin derivatives (method-specific algorithms).
Instruments Used
Automated analyzers
- Spectrophotometers / dedicated plasma hemoglobin methods on chemistry platforms
Manual methods
- Manual spectrophotometric plasma hemoglobin assays
Reference Values
Typical adult SI examples below follow widely published international hematology practice (e.g., Dacie and Lewis; Henry's). Always interpret against the method- and demographics-specific interval printed on the patient report (CLSI EP28-A3c). Neonatal, pediatric, pregnancy, and altitude intervals differ.
Normally very low (near method detection limits). Units may be mg/L or g/L; method-specific.
Interpretation
Common Causes of Increased Results
- Elevated plasma Hb supports intravascular hemolysis if pre-analytical hemolysis is excluded
Common Causes of Decreased Results
- Low/undetectable values are expected in health
Clinical Significance
- Intravascular hemolysis marker
- Device-related hemolysis monitoring
Factors Affecting Results
Pre-analytical
- Traumatic venipuncture; the dominant false-positive cause
- Vigorous tube shaking; pneumatic tube trauma in susceptible samples
Analytical
- Interference from turbidity or extreme icterus depending on method
Post-analytical
- Reporting elevated plasma Hb without noting possible draw artifact
Advantages and Limitations
Advantages
- Direct marker of free Hb in plasma
Limitations
- Easily confounded by in-vitro hemolysis
- Must be interpreted with haptoglobin, LDH, bilirubin, and smear when evaluating hemolysis
Clinical Pearls
If plasma hemoglobin is high but the draw was difficult, repeat with an atraumatic sample before calling intravascular hemolysis.
References
Authoritative textbooks, guidelines, and reviews supporting this laboratory test reference. Verify reference intervals, critical limits, and method details against institutional protocols and current guideline editions.
Textbooks
- McPherson RA, Pincus MR. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Elsevier; 2021.
- Rodak BF, Carr JH. Rodak's Hematology: Clinical Principles and Applications. 6th ed. Elsevier; 2020.
- Hoffbrand AV, Moss PAH, Pettit JE. Essential Haematology. 8th ed. Wiley-Blackwell; 2019.
- McKenzie SB, Williams JL. Clinical Laboratory Hematology. 4th ed. Pearson; 2022.
- Bain BJ, Bates I, Laffan MA. Dacie and Lewis Practical Haematology. 12th ed. Elsevier; 2017.
- Kaushansky K, et al. Williams Hematology. 10th ed. McGraw-Hill; 2021.
CLSI and Professional Guidelines
- Clinical and Laboratory Standards Institute. Defining, Establishing, and Verifying Reference Intervals in the Clinical Laboratory; Approved Standard. CLSI document EP28-A3c. CLSI; 2010.
- Clinical and Laboratory Standards Institute. Management of Critical- and Significant-Risk Results. CLSI guideline GP47-Ed1. CLSI; 2015.
WHO Publications
- World Health Organization. Guide to G6PD testing and counselling for safe use of 8-aminoquinoline drugs. WHO; 2022.
Frequently Asked Questions
Common questions about using this Plasma Hemoglobin laboratory test Medical Laboratory Library reference in Medical Laboratory Science education.
What is the Plasma Hemoglobin laboratory test reference used for?
This Medical Laboratory Library page summarizes the clinical importance of Plasma Hemoglobin. Review the Clinical Importance section for why the test is ordered in laboratory medicine practice.
Where can I find Plasma Hemoglobin specimen requirements?
See the Specimen Requirements section on this page for specimen information related to Plasma Hemoglobin. Confirm collection details against your laboratory protocol.
Where are Plasma Hemoglobin reference values listed?
See the Reference Values section on this Laboratory Library page. Reference ranges can vary by method and population, so verify intervals with your laboratory.
How do I interpret Plasma Hemoglobin results?
Use the Interpretation section for laboratory interpretation framing, including increased and decreased result patterns when provided. Do not treat educational text as a patient-specific diagnosis.
What analytical method is used for Plasma Hemoglobin?
See the Analytical Method section for principle and method notes. Method details may differ by instrument and institutional SOP.
Are related laboratory tests linked from Plasma Hemoglobin?
Yes. The Related Laboratory Tests section lists connected references for continued lookup in the Medical Laboratory Library.
How can I continue learning after reading Plasma Hemoglobin?
Use Continue learning links on this page for related Academy lessons, medical laboratory quizzes, or laboratory case studies when available for this Hematology topic.
What are the clinical pearls for Plasma Hemoglobin?
See the Clinical Pearls section for concise laboratory practice notes associated with Plasma Hemoglobin. Apply pearls alongside institutional protocols.
Reading progress
Awards XP once after you have meaningfully reviewed this article.