Protein Electrophoresis

Interpretation of Protein Electrophoresis

Introduction

Although a number of techniques for protein fractionation have been available for the past thirty years, protein electrophoresis has only been recently applied to avian diagnostics. Now routinely run in the Avian and Wildlife Laboratory, EPH has become an integral component in well bird/new bird screens as well as an accessory test in chlamydophilosis and aspergillosis testing. Please note that due to methodology changes, not all EPH run by different laboratories are equivalent. Take care in comparing results from different labs and use only lab established species specific reference intervals.

General Information on the Protein Electrophoresis

Plasma is applied to an electrical field on a gel substrate. Proteins migrate on the gel dependent on their chemical charge. After staining, the protein bands are enumerated by laser densitometry. Interpretations based on extensive reference ranges are included in every evaluation.

What does an abnormal EPH mean?

Abnormal EPH patterns are complicated to interpret. Mild to marked changes may be present in any one protein fraction. Often the combination of individual changes may be interpreted to aid in final diagnosis.

Pre-albumin: transporter protein, variable amounts in psittacine species, clinical significance unknown

Albumin: carrier protein which increases with dehydration; decreases have been linked to parasitism, acute nephritis, and hepatitis as well as over hydration. Decreases (i.e. low levels) are observed through 8 months of age.

Alpha-1: acute phase proteins; increases with parasitism, mild bacterial infections

Alpha-2: acute phase proteins; increases with parasitism, acute nephritis, general
acute and chronic inflammatory reactions

Beta: acute phase proteins; increases with acute nephritis, acute and chronic chlamydophilosis, aspergillosis and other mycotic diseases, mycobacteriosis, hepatitis

Gamma: immunoglobulins; increases with acute chlamydophilosis, aspergillosis, egg related peritonitis

Typical patterns

Some typical patterns can be observed with particular diseases:

  • Acute chlamydophilosis: albumin decreases, moderate to marked increases in beta and gamma globulins, beta-gamma bridging on EPH tracing
  • Chronic aspergillosis: moderate to marked increase in beta globulins
  • Hepatitis: Albumin decrease with or without an inverted pre-albumin:albumin ratio, beta and gamma increases with beta-gamma bridging
  • Acute nephritis: Albumin decrease with moderate increases in beta globulins with or without increases in alpha-2 globulins
  • Malnutrition: Albumin and gamma globulin decrease; some acute phase protein release
  • Non specific feather picking: mild increases in beta globulins
  • Non specific bacterial infection: mild increases in beta globulins
  • Sarcocystis infection: mild to moderate increases in beta and gamma globulins
  • Heavy Metal Toxicities: variable, beta globulin increases

When to use the test…

Approximately 30% of clinically normal birds will have an abnormal EPH pattern. Thus, EPH is an excellent screening test for well/new bird exams.

EPH is a strong accessory test for suspect liver and kidney disease cases as well as chlamydophilosis, sarcocystosis, and aspergillosis.

If all other tests fail to lead to diagnosis and the bird is clinically sick, EPH might help lead the way to other testing possibilities.

Sample Collection and Preparation

Heparinized plasma is preferred for this test. For best results, centrifuge the green top tube and separate the plasma to a small microfuge tube for transport to the lab. Mild hemolysis and lipemia are acceptable. Samples with more moderate levels of either will be run at the discretion of the lab.

References

C. Cray, M. Rodriguez, and J. Zaias. Protein electrophoresis of psittacine plasma. Vet Clin Path, 36(1):67-72, 2007.

C. Cray and L. Tatum. Application of protein electrophoresis in avian diagnostic testing. J Av Med Surg, 12:4-10, 1998.