Overview
Hemoglobin fractionation separates and quantifies normal and variant hemoglobins to characterize thalassemia traits and structural hemoglobin variants.
Clinical Importance
To investigate microcytosis, unexplained anemia, neonatal screening follow-up, and suspected sickle or other hemoglobin variants
To quantify HbA₂ and HbF in thalassemia evaluations
Specimen Requirements
- Specimen: whole blood
- Tube: lavender-top K₂EDTA (preferred) or K₃EDTA
- Anticoagulant: EDTA
- Handling: invert gently 8–10 times immediately after draw; do not shake
- Avoid recent transfusion when possible; donor Hb confounds patterns
Analytical Method
Hemoglobins separate by charge (electrophoresis/capillary electrophoresis) or by ion-exchange HPLC retention time. Peaks/bands are identified by position and quantified as percentages.
Instruments Used
Automated analyzers
- HPLC hemoglobinopathy systems (e.g., Bio-Rad Variant-class platforms)
- Capillary electrophoresis hemoglobin systems
Manual methods
- Alkaline and acid gel electrophoresis with densitometry
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.
Healthy adults: predominantly HbA; HbA₂ typically about 2.0–3.5%; HbF usually <1–2% (method-specific).
Neonates: high HbF is physiologic; adult patterns emerge over the first months of life.
Interpret fractions with CBC indices and iron status; iron deficiency can lower HbA₂.
Interpretation
Common Causes of Increased Results
- Elevated HbA₂ and/or HbF patterns support thalassemia trait evaluation
- Presence of HbS, HbC, or other variant peaks requires confirmatory context (solubility, acid electrophoresis, molecular testing as indicated)
Common Causes of Decreased Results
- Unexpectedly low HbA₂ may reflect iron deficiency or delta-thalassemia contexts; correlate clinically
Clinical Significance
- Hemoglobinopathy and thalassemia laboratory characterization
- Confirmation after positive sickle solubility screens
Factors Affecting Results
Pre-analytical
- Recent transfusion
- Mislabeling
Analytical
- Co-eluting variants on HPLC
- Method differences in HbA₂ quantification
Post-analytical
- Reporting variants without CBC correlation
Advantages and Limitations
Advantages
- Quantitative fractionation of major hemoglobins
- HPLC/CE offer high throughput and resolution
Limitations
- Some rare variants co-elute and need second-line methods
- Does not replace DNA testing when definitive genotyping is required
Clinical Pearls
Never interpret an isolated HbA₂ percentage without the CBC; microcytosis and iron status change the meaning of the same number.
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 Hemoglobin Electrophoresis / HPLC laboratory test Medical Laboratory Library reference in Medical Laboratory Science education.
What is the Hemoglobin Electrophoresis / HPLC laboratory test reference used for?
This Medical Laboratory Library page summarizes the clinical importance of Hemoglobin Electrophoresis / HPLC. Review the Clinical Importance section for why the test is ordered in laboratory medicine practice.
Where can I find Hemoglobin Electrophoresis / HPLC specimen requirements?
See the Specimen Requirements section on this page for specimen information related to Hemoglobin Electrophoresis / HPLC. Confirm collection details against your laboratory protocol.
Where are Hemoglobin Electrophoresis / HPLC 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 Hemoglobin Electrophoresis / HPLC 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 Hemoglobin Electrophoresis / HPLC?
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 Hemoglobin Electrophoresis / HPLC?
Yes. The Related Laboratory Tests section lists connected references for continued lookup in the Medical Laboratory Library.
How can I continue learning after reading Hemoglobin Electrophoresis / HPLC?
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 Hemoglobin Electrophoresis / HPLC?
See the Clinical Pearls section for concise laboratory practice notes associated with Hemoglobin Electrophoresis / HPLC. Apply pearls alongside institutional protocols.
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