Hemoglobin A2 Fraction (from Hemoglobin A1c Subtype Analysis)
This test measures a specific type of hemoglobin (the protein in red blood cells that carries oxygen) called Hemoglobin A2. It helps assess how well your body is producing this particular form of hemoglobin, which can be important in certain blood disorders.
["HbA2 helps diagnose and monitor conditions like thalassemia."]
Key facts at a glance
- LOINC
- 51615-3
- Short code
- Hgb A2+C MFr Bld
- Synonyms
- Hgb A2+C MFr Bld
- Category
- hematology
- Sample
- whole-blood
- Container
- Lavender-top (EDTA)
- 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
- 3 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
The HbA2 test is done to help your doctor find out whether you may have an inherited hemoglobin disorder, such as beta thalassemia, that affects the way your red blood cells carry oxygen throughout your body.
Your healthcare provider may order this test if you have symptoms of a blood disorder, such as anemia, fatigue, or pale skin. It’s also used to confirm or monitor conditions like thalassemia, a genetic disorder that affects how your body makes hemoglobin. Sometimes, it’s part of a broader hemoglobin A1c analysis to check for underlying blood diseases.
This test measures the amount of hemoglobin A2 (HbA2) in your blood. HbA2 is a normal form of hemoglobin that makes up a small portion of your total hemoglobin, and measuring its level helps identify certain inherited blood conditions.
HbA2 is a type of hemoglobin that develops gradually over time. Unlike the more commonly measured Hemoglobin A1c (which reflects average blood sugar levels), HbA2 specifically measures the proportion of Hemoglobin A2 in your red blood cells. This fraction can be elevated in thalassemia and other inherited blood disorders.
A health care professional will draw a small blood sample from a vein in your arm, usually at the inside of your elbow. No fasting or special preparation is needed, so you can eat and drink normally before your appointment.
This test uses a sample of whole blood, typically collected via a simple venipuncture (blood draw). The blood is processed to separate the red blood cells, where the HbA2 fraction is analyzed using specialized laboratory techniques.
Your results are used to help diagnose beta thalassemia and other hemoglobin disorders, to evaluate anemia that has no clear cause, and to guide decisions about treatment, follow-up testing, and genetic counseling for you and your family.
Results help diagnose or manage conditions like thalassemia by providing insight into the proportion of abnormal hemoglobin variants. It’s often used alongside other tests, such as Hemoglobin A1c, to tailor treatment plans and monitor disease progression.
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: HbA2 in Blood Disorders
Short name
HbA2
Frequently asked questions
HbA2 levels can be higher than normal in thalassemia, a genetic disorder causing reduced production of healthy hemoglobin. Detecting elevated HbA2 helps confirm the diagnosis and guides treatment, such as blood transfusions or iron chelation therapy. It’s also useful in screening for other hemoglobinopathies or in patients with unexplained anemia.
An elevated HbA2 level may indicate thalassemia or another inherited blood disorder. A lower-than-normal level might suggest conditions like iron deficiency anemia or other genetic blood disorders. Your healthcare provider will discuss results in the context of your symptoms and other test findings.
The frequency depends on your health condition. If you have thalassemia or another related disorder, your doctor may recommend regular monitoring. If this test is part of a routine checkup or screening, your provider will specify the schedule.
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