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Test ID HGBCE Hemoglobin Variant, A2 and F Quantitation, Blood


Ordering Guidance


This test is intended for monitoring purposes, such as the increase in hemoglobin F after therapy or the levels of hemoglobin variants after transfusion.

 

If the patient has never been appropriately studied, hemoglobin electrophoresis is necessary; see HBEL1 / Hemoglobin Electrophoresis Evaluation, Blood.

 

Multiple hematology evaluations are available. For information on testing that is performed with each evaluation, see Benign Hematology Evaluation Comparison.



Specimen Required


Container/Tube:

Preferred: Lavender top (EDTA)

Acceptable: Yellow top (ACD) or green top (heparin)

Specimen Volume: 4 mL

Collection Instructions:

1. Submit fresh specimen.

2. Send whole blood specimen in original tube. Do not aliquot.


Forms

1. Metabolic Hematology Patient Information (T810)

2. If not ordering electronically, complete, print, and send a Benign Hematology Test Request Form (T755) with the specimen.

Secondary ID

65039

Useful For

Monitoring patients with sickling disorders who have received hydroxyurea or transfusion therapy

 

This test is not intended for diagnostic purposes.

 

This test is not useful for screening purposes.

Method Name

Capillary Electrophoresis

Reporting Name

Hb Variant, A2 and F Quantitation,B

Specimen Type

Whole Blood EDTA

Specimen Minimum Volume

1 mL

Specimen Stability Information

Specimen Type Temperature Time
Whole Blood EDTA Refrigerated 10 days

Clinical Information

The treatment of red blood cell sickling disorders may involve many therapeutic modalities. Two of the most important and beneficial are treatment with hydroxyurea and chronic transfusion therapy. Hydroxyurea causes elevation of fetal hemoglobin (HbF) levels, and transfusion serves to lower the percentage of hemoglobin S (HbS). Both of these therapeutic modalities act to lessen the number and severity of sickling crises. Thus, periodic monitoring of HbF and HbS levels are needed to guide further therapy.

Reference Values

HEMOGLOBIN A

0-30 days: 5.9-77.2%

1-2 months: 7.9-92.4%

3-5 months: 54.7-97.1%

6-8 months: 80.0-98.0%

9-12 months: 86.2-98.0%

13-17 months: 88.8-98.0%

18-23 months: 90.4-98.0%

≥24 months: 95.8-98.0%

 

HEMOGLOBIN A2

0-30 days: 0.0-2.1%

1-2 months: 0.0-2.6%

3-5 months: 1.3-3.1%

≥6 months: 2.0-3.3%

 

HEMOGLOBIN F

0-30 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%

≥24 months: 0.0-0.9%

 

VARIANT 1

0.0

 

VARIANT 2

0.0

 

VARIANT 3

0.0

Cautions

Peaks present in zones Z9, Z7, Z6, Z5, Z4, Z3, and Z2-recently labeled the Z(A), Z(F), Z(D), Z(S), Z(E), Z(A2), and Z(C) zones, respectively-may not represent the hemoglobin fractions the zones are named after as other variants can migrate to these zones, including the S, F, A, and A2 positions.

 

Although the most common variants are easily detected, many hemoglobin variants are not detected by the capillary electrophoresis method alone or can migrate with, and cannot be discriminated from, common variants. Therefore, this test should not be used for screening purposes due to low sensitivity.

 

Recent transfusion may mask protein results including hemoglobin electrophoresis, hereditary persistence of fetal hemoglobin by flow cytometry, stability studies, and sickle solubility studies depending on percentage of transfused cells present.

 

Some hemoglobin variants can originate from the donor blood product and not from the tested recipient. These are typically found in low percentage.

 

Some hemoglobin variants do not sufficiently resolve from other peaks, which precludes separate quantitation of percentages. These will be reported as a single percentage that represents more than 1 variant.

 

Some therapies cause artefactual effects in protein studies, including Voxelotor (artefactual peaks). These peaks may vary between samples or patients.

Day(s) Performed

Monday through Friday

Report Available

Same day/1 to 2 days

Performing Laboratory

Mayo Clinic 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. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

83020

NY State Approved

Yes