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HelpTest ID HPFH Hemoglobin F, Red Cell Distribution, Blood
Useful For
Distinguishing large deletional hereditary persistence of fetal hemoglobin from other conditions with increased percentage of fetal hemoglobin
Reflex Tests
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| HBF | Hemoglobin F, B | Yes | No |
Testing Algorithm
The percent of the patient’s hemoglobin F is very important to the clinical utility of this test. HBF / Hemoglobin F, Blood will be performed at an additional charge to determine if Hemoglobin F, Red Cell Distribution testing is warranted. If the hemoglobin F value from HBF / Hemoglobin F, Blood are normal for age or if value is <5% the HPFH / Hemoglobin F, Red Cell Distribution, Blood will not be performed. Samples with hemoglobin F (Hb F) levels >35% will be accepted but are discouraged due to decreased test specificity. For these markedly elevated Hb F levels, a hemoglobin electrophoresis profile with request for beta globin gene molecular testing for elevated Hb F levels is recommended.
Method Name
Flow Cytometry
Reporting Name
Hemoglobin F, Red Cell Distrib, BSpecimen Type
Whole Blood EDTAContainer/Tube: Lavender top (EDTA)
Specimen Volume: 3 mL
Additional Information:
1. Patient's age and sex are required.
2. Indicate
the percent of hemoglobin F detected by hemoglobin electrophoresis.
If this is not indicated, we will perform HBF / Hemoglobin F,
Blood.
3. Indicate the reason for testing.
4. For
information on thalassemias and appropriate test ordering, see
Thalassemia Tests in Special Instructions.
Forms: If not ordering electronically, complete, print, and send a Benign Hematology Test Request Form (T755) with the specimen (http://www.mayomedicallaboratories.com/it-mmfiles/benign-hematology-test-request-form.pdf)
Specimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Whole Blood EDTA | Refrigerated | 7 days |
Clinical Information
More than 75% of the hemoglobin of the newborn is hemoglobin F (Hb F); it diminishes over a period of several months to adult levels, becoming <2% by 1 year-of-age and <1% by 2 years.
Hb F may constitute 90% of the total hemoglobin in patients with beta-thalassemia major or other combinations of beta thalassemia and fetal hemoglobin (HPFH) mutations.
Hb F is often mildly to moderately elevated in sickle cell disease, aplastic anemia, acute leukemia, myeloproliferative disorders such as juvenile myelomonocytic leukemia (JMML), hereditary spherocytosis, and alpha-thalassemia minor. It is commonly increased in hemoglobinopathies associated with hemolysis. Hb F increases to as high as 10% during normal pregnancy. Hb F is also increased due to medications such as hydroxyurea, decitabine, and lenalidomide. Elevation in Hb F has a been cited as a discriminator between Diamond-Blackfan congenital pure red cell aplasia (elevated) and transient erythroblastopenia of childhood (normal) but whether this simply reflects the chronicity of anemia inherent to the former condition rather than a specific finding is unclear.
In the common (large deletional) form of the genetic trait hereditary persistence of HPFH, all of the erythrocytes contain Hb F. When tested by flow cytometry using specificity for Hb F, these HPFH cases display a homocellular distribution pattern of Hb F within the red cell population. Other causes of increased Hb F including delta beta thalassemia, hydroxyurea, and some nondeletional HPFH mutations typically display a heterocellular distribution of Hb F within the red cells, reflecting disparate populations of F cells and cells lacking Hb F. Quantification of Hb F percentage should be determined prior to flow cytometry of Hb F red cell distribution to establish the appropriateness of this test. The flow cytometry analysis of elevated Hb F levels is useful when Hb F percentage is between 15% to 35% and the clinical differential diagnosis includes large deletional HPFH. Hb F percentages below 15% are likely not due to large deletional HPFH and causes of Hb F percentages above 35% are better confirmed by molecular and family studies. This test is not to be ordered for fetal-maternal bleed. If fetal maternal bleed assessment is desired, please see FMB / Fetomaternal Bleed, Flow Cytometry, Blood.
Reference Values
Reported as heterocellular or homocellular
Cautions
For hereditary persistence of fetal hemoglobin only. Not to be ordered for fetal-maternal bleed (see FMB / Fetomaternal Bleed, Flow Cytometry, Blood).
With hemoglobin F values >35%, most specimens show a homocellular pattern; this does not necessarily indicate hereditary persistence of fetal hemoglobin. Clinical correlation is needed.
Day(s) Performed
Monday through Saturday; continuously
Report Available
2 days (Not reported on Saturday or Sunday)Performing Laboratory
Mayo Medical Laboratories in Rochester
Test Classification
This test has been modified from the manufacturer’s instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements.CPT Code Information
88184