View source for Medicine:Hemoglobin electrophoresis

{{Short description|Blood test}}
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 |caption         = Schematic of alkaline hemoglobin electrophoresis, showing expected results for a normal adult, normal newborn, person with [[Medicine:Sickle cell disease|sickle cell disease]], person with [[Medicine:Sickle cell trait|sickle cell trait]], person with hemoglobin SC disease, and control sample.

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'''Hemoglobin electrophoresis''' is a [[Medicine:Blood test|blood test]] that can detect different types of [[Biology:Hemoglobin|hemoglobin]]. The test can detect hemoglobin S, the form associated with [[Medicine:Sickle cell disease|sickle cell disease]], as well as other abnormal types of hemoglobin, such as [[Medicine:Hemoglobin C|hemoglobin C]]. It can also be used to investigate [[Medicine:Thalassemia|thalassemia]]s, which are disorders caused by defective hemoglobin production.

==Procedure==
The test uses the principles of [[Biology:Gel electrophoresis|gel electrophoresis]] to separate out the various types of hemoglobin and is a type of native gel electrophoresis. After the sample has been treated to release the hemoglobin from the red cells, it is introduced into a porous gel (usually made of [[Chemistry:Agarose|agarose]] or [[Chemistry:Cellulose acetate|cellulose acetate]]) and subjected to an electrical field, most commonly in an [[Chemistry:Alkaline|alkaline]] medium. Different hemoglobins have different charges, and according to those charges, they move at different speeds in the gel and eventually form discrete bands (see [[Medicine:Hemoglobinopathy#Electrophoretic migration patterns|electrophoretic migration patterns]]). A [[Organization:Laboratory quality control|quality control]] sample containing hemoglobins A, F, S, and C is run along with the patient sample to aid in identifying the different bands.<ref name="Kottke2012">{{cite book|last1=Kottke-Marchant|first1=K|last2=Davis|first2=B|title=Laboratory Hematology Practice|url=https://books.google.com/books?id=dlZDhbXDuOQC|year= 2012|publisher=John Wiley & Sons|isbn=978-1-4443-9857-1|edition=1|pages=571–2}}</ref><ref name="Proytcheva2011">{{cite book|last=Proytcheva|first=MA|title=Diagnostic Pediatric Hematopathology|url=https://books.google.com/books?id=8s8stgvB1kUC&pg=PA65|date=3 February 2011|publisher=Cambridge University Press|isbn=978-0-521-88160-9|pages=65–6}}</ref> The relative amounts of each type of hemoglobin can be estimated by measuring the optical density of the bands, though this method is not reliable for hemoglobins that are present in low quantities.<ref name="Proytcheva2011"/>

Because hemoglobins exhibit different migration patterns depending on the [[Chemistry:PH|pH]] level, testing the same sample at both an acid and an alkaline pH can help to identify some abnormal hemoglobins that would otherwise be impossible to distinguish from others.{{r|Keohane2015|p=437}}
==Clinical significance==
Adult human blood normally contains three types of hemoglobin: [[Biology:Hemoglobin A|hemoglobin A]], which makes up approximately 95% of the total; [[Biology:Hemoglobin A2|hemoglobin A<sub>2</sub>]], which accounts for less than 3.5%; and a minute amount of hemoglobin F.<ref name="Keohane2015">{{cite book|last1=Keohane|first1=E|last2=Smith|first2=L|last3=Walenga|first3=J|title=Rodak's Hematology: Clinical Principles and Applications|url=https://books.google.com/books?id=UC3uBgAAQBAJ|year=2015|publisher=Elsevier Health Sciences|isbn=978-0-323-23906-6|edition=5}}</ref>{{rp|140}} If abnormal hemoglobin variants such as hemoglobin S (which occurs in [[Medicine:Sickle cell disease|sickle cell disease]]), [[Medicine:Hemoglobin C|C]] or [[Medicine:Hemoglobin E|E]] are present, they will appear as unexpected bands on electrophoresis (provided they do not migrate to the same place as other hemoglobins).<ref name="Kottke2012"/>

Hemoglobin electrophoresis can also be used to investigate [[Medicine:Thalassemia|thalassemia]]s, which are caused by decreased production of subunits of the hemoglobin molecule. Hemoglobin A<sub>2</sub> levels are typically elevated in beta-thalassemia minor and hemoglobin F may be slightly increased. In beta-thalassemia major, hemoglobin A is decreased (or in some cases absent) and hemoglobin F is markedly elevated; A<small>2</small> levels are variable.{{r|Keohane2015|pp=461–2}} In [[Medicine:Hemoglobin H disease|hemoglobin H disease]], a form of [[Medicine:Alpha-thalassemia|alpha-thalassemia]], an abnormal band of hemoglobin H can be detected, and sometimes a band of [[Biology:Hemoglobin Barts|Hemoglobin Barts]]; but in the milder alpha-thalassemia trait, electrophoresis results are effectively normal.<ref name="McPherson2017">{{cite book|last1=McPherson|first1=RA|last2=Pincus|first2=MR|title=Henry's Clinical Diagnosis and Management by Laboratory Methods|url=https://books.google.com/books?id=xAzhCwAAQBAJ|year= 2017|publisher=Elsevier Health Sciences|isbn=978-0-323-41315-2|edition=23|page=590}}</ref>

==History==
[[Biography:Linus Pauling|Linus Pauling]] is credited with the invention of hemoglobin electrophoresis in 1949. Newer alternatives to conventional hemoglobin electrophoresis include [[Biology:Isoelectric focusing|isoelectric focusing]], capillary zone electrophoresis, and [[High-performance liquid chromatography|high-performance liquid chromatography]].<ref name="Proytcheva2011"/>
==References==
{{Reflist}}
{{DEFAULTSORT:Hemoglobin Electrophoresis}}
[[Category:Blood tests]]

{{Sourceattribution|Hemoglobin electrophoresis}}