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Test ID HBELC Hemoglobin Electrophoresis Cascade, Blood

Reporting Name

HGB Electrophoresis Cascade

Useful For

Diagnosis and comprehensive classification of thalassemias and hemoglobin variants

Profile Information

Test ID Reporting Name Available Separately Always Performed
A2F Hemoglobin A2 and F No Yes
HBEL Hemoglobin Electrophoresis, B No Yes

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
SDEX Hemoglobin S, Scrn, B Yes No
IEF IEF Confirms No No
MASS Hb Variant by Mass Spec, B No No
UNHB Unstable Hemoglobin, B No No
ATHAL Alpha-Globin Gene Analysis Yes No
WASQR Alpha Globin Gene Sequencing, B Yes, (Order WASEQ) No
WBSQR Beta Globin Gene Sequencing, B Yes, (Order WBSEQ) No
WBDDR Beta Globin Cluster Locus Del/Dup,B Yes, (Order WBDD) No
HBELA HGB Electrophoresis Summary Interp No No
HPFH Hemoglobin F, Red Cell Distrib, B No No
WGSQR Gamma Globin Full Gene Sequencing No No

Testing Algorithm

Hemoglobin electrophoresis cascade will always include hemoglobin A(2) and F and hemoglobin electrophoresis utilizing cation exchange HPLC and capillary electrophoresis methods.

 

Hemoglobin electrophoresis reflex testing, performed at additional charge, may include any or all of the following to identify rare hemoglobin variants present: sickle solubility (hemoglobin S screen), hemoglobin heat and isopropanol stability studies (unstable hemoglobin), isoelectric focusing, intact globin chain mass spectrometry (hemoglobin variant by mass spectrometry), Hb F distribution by flow cytometry (hemoglobin F red cell distribution), DNA (Sanger) testing for beta chain variants and the most common beta thalassemias (beta-globin gene sequencing), multiplex ligation-dependent probe amplification (MLPA) testing for beta cluster locus large deletions and duplications, including large deletional hereditary persistence of fetal hemoglobin (HPFH), delta-beta (DBT), delta thalassemias, gamma-delta-beta (GDBT), and epsilon-gamma-delta-beta (EGDBT) thalassemias (beta globin cluster locus del/dup), large deletional alpha thalassemias and alpha gene duplications (alpha-globin gene analysis), alpha chain variants and non-deletional alpha thalassemias (alpha-globin gene sequencing), and gamma chain variants and non-deletional HPFH (gamma globin full gene sequencing).

 

If a Thalassemia/Hemoglobinopathy Patient Information sheet (T358) is received with the sample, the reported clinical features or clinical impression will be considered in the interpretation and focus of the evaluation. Our laboratory has extensive experience in hemoglobin variant identification and many cases can be confidently classified without molecular testing. However, molecular confirmation is always available. If no molecular testing or, conversely, specific molecular tests are desired, utilize the appropriate check boxes on the information sheet. If the information sheet or other communication is not received, the reviewing hematopathologist will select appropriate tests to sufficiently explain the clinical impression or reported CBC results, which may or may not include molecular testing.

 

Hemoglobin (HGB) Electrophoresis Summary Interpretation, an additional consultative interpretation that summarizes all testing, will be provided after test completion to incorporate subsequent results into an overall evaluation if 1 or more of the following molecular tests are reflexed on the HBELC / Hemoglobin Electrophoresis Cascade, Blood:

-ATHAL / Alpha-Globin Gene Analysis

-WASQR / Alpha-Globin Gene Sequencing, Blood

-WBSQR / Beta-Globin Gene Sequencing, Blood

-WBDDR / Beta-Globin Cluster Locus Deletion/Duplication, Blood

-WGSQR / Gamma-Globin Full Gene Sequencing

 

See Benign Hematology Evaluation Comparison in Special Instructions.

Specimen Type

Whole Blood EDTA


Advisory Information


Alpha-thalassemias with only 1 or 2 alpha-globin gene deletions are not recognized by this testing protocol. ATHAL / Alpha-Globin Gene Analysis is required to identify 1 or 2 globin gene deletions.



Necessary Information


Include recent transfusion information.

 

Include most recent CBC results.



Specimen Required


Container/Tube:

Preferred: Lavender top (EDTA)

Acceptable: ACD (solution B), green top (sodium heparin)

Specimen Volume: 10 mL

Collection Instructions: Send specimen in original tube. Do not aliquot.


Specimen Minimum Volume

1 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Whole Blood EDTA Refrigerated 7 days

Reference Values

HEMOGLOBIN A

1-30 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

1-30 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

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%

≥24 months: 0.0-0.9%

 

VARIANT

No abnormal variants

 

VARIANT 2

No abnormal variants

 

VARIANT 3

No abnormal variants

Day(s) and Time(s) Performed

Monday through Saturday 

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 U.S. Food and Drug Administration.

CPT Code Information

Hemoglobin Electrophoresis Cascade

83020-Quantitation by electrophoresis

83021-Quantitation by HPLC

 

IEF Confirms

82664-Electrophoresis, not elsewhere specified (if appropriate)

 

Hemoglobin, Unstable, Blood

83068 (if appropriate)

 

Hemoglobin Variant by Mass Spectrometry (MS), Blood

83789 (if appropriate)

 

Hemoglobin F, Red Blood Cell Distribution, Blood

88184 (if appropriate)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
HBELC HGB Electrophoresis Cascade 94538-6

 

Result ID Test Result Name Result LOINC Value
2380 Hemoglobin A 20572-4
2381 Hemoglobin A2 42245-1
2382 Hemoglobin F 42246-9
2383 Variant 32017-6
29224 Variant 2 32017-6
29225 Variant 3 32017-6
2101 Interpretation 78748-1

Clinical Information

Hemoglobin abnormalities not uncommonly occur as compound disorders (2 or more mutations) that can have complex interactions and variable phenotypes. Although powerful as an adjunct for a complete and accurate diagnosis, genetic methods alone can give incomplete and possibly misleading information due to limitations of the methods. Interpretation of genetic data requires the incorporation of protein analysis results. This profile is well-suited for the classification of hemoglobin disorders.

 

A large number (>1,000) of variants of hemoglobin (Hb) have been recognized. They are identified by capital letters (eg, Hb A or Hb S), or by the city in which the variant was first discovered (eg, Hb Koln). Clinical symptoms that can be associated with hemoglobin disorders include microcytosis, sickling disorders, hemolysis, erythrocytosis, cyanosis/hypoxia, long-standing or familial anemia, compensated or episodic anemia, and increased methemoglobin or sulfhemoglobin results.

 

Mayo Clinic Laboratories receives specimens for this test from a wide geographic area and nearly one-half of all specimens received exhibit abnormalities. The most common abnormality is an increase in Hb A2 to about 4% to 8%, which indicates beta-thalassemia minor in the correct clinical context. A wide variety of other hemoglobinopathies also have been encountered. Ranked in order of relative frequency, these are: Hb S (sickle cell disease and trait), C, E, Lepore, G-Philadelphia, H, D-Los Angeles, Koln, Constant Spring, O-Arab, and others. Hb C and S are found mostly in people from west or central Africa and Hb E and H in people from Southeast Asia. Hemoglobin electrophoresis is often used in the evaluation of unexplained microcytosis, thus accounting for the frequent detection of Hb Lepore, which is relatively common in Italians and others of Mediterranean ancestry and in Hb E, which is relatively common in Southeast Asians resettled in the United States; microcytosis is characteristic of both Hb Lepore and Hb E.

 

Alpha-thalassemia is very common in the United States, occurring in approximately 30% of African Americans and accounting for the frequent occurrence of microcytosis in persons of this ethnic group. Some alpha-thalassemias (ie, hemoglobin variants H, Barts, and Constant Spring) are easily identified in the hemoglobin electrophoresis protocol. However, alpha-thalassemias that are from only 1 or 2 alpha-globin gene deletions are not recognized by protein studies alone. For the diagnosis of alpha-thalassemias, deletion and duplication testing is required.

Interpretation

The types of hemoglobin present are identified, quantitated, and an interpretive report is issued.

Clinical Reference

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

Analytic Time

2 to 25 days if structural and/or molecular studies are required

Method Name

A2F: Cation Exchange/High-Performance Liquid Chromatography (HPLC)

HBEL: Capillary Electrophoresis

IEF: Isoelectric Focusing

MASS: Mass Spectrometry (MS)

HPFH: Flow Cytometry

UNHB: Isopropanol and Heat Stability

HBELA: Consultative Interpretation

Forms

1. New York Clients-Informed consent is required. Document on the request form or electronic order that a copy is on file. The following documents are available in Special Instructions:

-Informed Consent for Genetic Testing (T576)

-Informed Consent for Genetic Testing-Spanish (T826)

2. Metabolic Hematology Patient Information (T810) in Special Instructions

3. If not ordering electronically, complete, print, and send 1 of the following forms with the specimen:

-General Request (T239)

-Benign Hematology Test Request (T755)