Test ID: A2F
Hemoglobin A2 and F, Blood
Secondary ID 
A test code used for billing and in test definitions created prior to November 2011
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Useful For Suggests clinical disorders or settings where the test may be helpful
Assisting in the diagnosis of beta-thalassemia
Quantitating the percent of hemoglobin F (Hgb F) present
Assisting in the diagnosis of disorders with elevated levels of Hgb F
Special Instructions and Forms Describes specimen collection and preparation information, test algorithms, and other information pertinent to test. Also includes pertinent information and consent forms to be used when requesting a particular test
Method Name A short description of the method used to perform the test
Cation Exchange/High-Performance Liquid Chromatography (HPLC)
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Aliases Lists additional common names for a test, as an aid in searching
F-Hemoglobin
Hemoglobin A2
Hemoglobin A2 and F, Blood
Hemoglobin F
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Container/Tube:
Preferred: Lavender top (EDTA)
Acceptable: ACD, heparin
Specimen Volume: 6 mL
Collection Instructions:
1. Submit fresh specimen.
2. Do not transfer blood to other containers.
Additional Information: Patient's age is required.
Forms:
1. Thalassemia/Hemoglobinopathy Information Sheet (Supply T358) in Special Instructions
2. If not ordering electronically, please submit a Hematopathology/Molecular Oncology Request Form (Supply T241) with the specimen.
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected
| Hemolysis | Mild OK; Gross OK |
| Lipemia | NA |
| Icterus | NA |
| Other | NA |
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
| Specimen Type | Temperature | Time |
|---|---|---|
| Whole blood | Refrigerated | 10 days |
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Hemoglobin F (Hgb F), composed of 2 alpha and 2 gamma globin chains, is the normal hemoglobin of the fetus and newborn. Normally in the second trimester, gamma chain production (and Hgb F levels) decrease and beta chain production increases, resulting in increasing levels of Hgb A, the major normal adult Hgb (2 alpha and 2 beta globin chains). Hgb A2 (2 alpha and 2 delta globin chains) also comprises a small amount (<3.3%) of Hgb normally found in adults. Hgb A2 values at birth are <1%.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
HEMOGLOBIN A2
1-30 days: 0.0-2.1%
1-2 months: 0.0-2.6%
3-5 months: 1.3-3.1%
> or =6 months: 2.0-3.3%
HEMOGLOBIN F
1-30 days: 22.8-92.0%
1-2 months: 7.6-89.8%
3-5 months: 1.6-42.2%
6-8 months: 0.0-16.7%
9-12 months: 0.0-10.5%
13-17 months: 0.0-7.9%
18-23 months: 0.0-6.3%
> or =24 months: 0.0-0.9%
Interpretation Provides information to assist in interpretation of the test results
Hemoglobin A2 (Hgb A2) values of 3.5% to 9% are found in beta-thalassemia trait.
In beta-thalassemia major, hemoglobin F (Hgb F) may be 30% to 90% or even more of the total hemoglobin.
Hgb F concentration is usually between 5% to 15% of the total hemoglobin in delta/beta-type thalassemia trait (F-thalassemia).
Higher concentrations of Hbg F occur in hemoglobin S (Hgb S)/beta zero-thalassemia, in patients who are doubly heterozygous for the Hgb S gene, and in patients who have a gene for hereditary persistence of fetal hemoglobin (HPFH). These disorders may be differentiated by family studies or by flow cytometry studies for Hgb F (HPFH/8270 Hemoglobin F, Red Cell Distribution, Blood), which reveals uniform intraerythrocytic distribution of Hgb F in HPFH and nonuniform distribution in Hgb S/beta thalassemia.
The electrophoretic finding of small quantities of Hgb A in a patient who has mostly Hgb S and a moderate increase in Hgb F is strong evidence of Hgb S/beta thalassemia (if the patient has not had a transfusion).
Hgb F values greater than normal (2%) may be seen in chronic anemias, beta-thalassemia, and HPFH
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Hemoglobin F (Hgb F) is elevated in newborns, reaching adult levels by 12 months.
Hgb F is commonly increased to as much as 5% to 10% in normal pregnancy.
Slight elevation in hemoglobin A2 may also occur in hyperthyroidism or when there is deficiency of vitamin B12 or folate.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
Hoyer JD, Hoffman DR: The thalassemia and hemoglobinopathy syndromes. In Clinical Laboratory Medicine. Second edition. Edited by KD McMlatchey. Philadelphia, Lippincott, Williams and Wilkins, 2002 pp 866-895
Method Description Describes how the test is performed and provides a method-specific reference
Hemolysate of whole blood is injected into an analysis stream passing through a cartridge containing diethylaminoethyl-resin using HPLC. A pre-programmed gradient controls the elution buffer mixture that also passes through the analytical cartridge. The ionic strength of the elution buffer is raised by increasing the percentage of a second buffer. As the ionic strength of the buffer increases the more strongly retained hemoglobins elute from the cartridge. Absorbance changes are detected by a dual-wavelength filter photometer. Changes in absorbances are displayed as a chromatogram of absorbances versus time.(Huismann TH, Scroeder WA, Brodie AN, et al: Microchromotography of hemoglobins. III. A simplified procedure for the determination of hemoglobin A2. J Lab Clin Med 1975;86:700-702; Ou CN, Buffone GJ, Reimer GL, Alpert AJ: High-performance liquid chromatography of human hemoglobins on a new cation exchanger. J Chromatogr 1983;266:197-205)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Monday through Saturday; 7 a.m. and 1 p.m.
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
Test Classification Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
CPT Code Information Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
83021
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
| Result ID | Reporting Name | LOINC Code |
|---|---|---|
| 2381 | Hemoglobin A2 | 4551-8 |
| 2382 | Hemoglobin F | 4576-5 |
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