Serum electrophoresis
The serum electrophoresis (more precisely, serum protein electrophoresis ) is a medical laboratory test in which the proteins of the blood serum (serum proteins) by means of a native gel electrophoresis on a cellulose acetate strip or agarose gel to be separated.
principle
Serum (no longer contains coagulation factors ) is used for electrophoresis. Plasma (with coagulation factors) is unsuitable because the fibrinogen it contains simulates a monoclonal band during electrophoresis and is easy to confuse. No hemolytic samples (with destroyed blood cells) are used either, because the hemolysis increases the α 2 and β fractions.
Depending on the migration in the electric field, a distinction is made between the following fractions:
| Protein fraction | Proportion of (%) | Important components (selection) | reduced | elevated | |
|---|---|---|---|---|---|
| albumin | 58.0-70.0 | albumin | Liver cirrhosis , nephrotic syndrome , inflammatory bowel disease | ||
| α 1 - globulins | 1.5-4.0 | α 1 antitrypsin , α 1 lipoprotein (HDL) | Cirrhosis of the liver | Inflammation , nephrotic syndrome | |
| α 2 -globulins | 5.0-10.0 | Ceruloplasmin , haptoglobin , plasminogen | Cirrhosis of the liver | Inflammation , nephrotic syndrome | |
| β-globulins | 8.0-13.0 | β-lipoprotein , transferrin , beta-2-microglobulin , complement proteins | Liver cirrhosis (typical shoulder formation towards the γ fraction) | nephrotic syndrome , paraproteinemia | |
| γ-globulins | 10.0-19.0 | Immunoglobulins ( antibodies ) | nephrotic syndrome , antibody deficiency syndromes | chron. Diseases, multiple myeloma , cirrhosis of the liver | |
evaluation
When assessing electrophoresis, it is crucial to be aware that the sum of the proteins shown always represents 100% of the serum protein. If a fraction is reduced, the other fractions appear relatively increased, although they are unchanged in absolute terms. It is therefore advisable to always determine and take into account the total protein concentration in parallel.
Deviations from the normal distribution are called dysproteinemia . Some typical changes in protein electrophoresis in certain disease constellations are the following:
- Acute inflammation: decrease in albumin, increase in α 1 and α 2 globulins ( "acute phase" proteins )
- chronic inflammatory processes: decrease in albumin, increase in α 2 - and γ-globulins
- Liver cirrhosis: strong decrease in albumin, clear broad-based increase in γ-globulins
- Plasmacytoma: Decrease in albumin, strong increase (narrow-base spike) in gamma globulins or, less frequently, in the range of β-globulins
- Nephrotic syndrome: strong decrease in albumin, marked increase in α 2 -globulins, increase in β- and decrease in γ-globulins
If a narrow-base spike can be seen in the γ-globulin fraction (more rarely also in the β-fraction), this indicates a so-called monoclonal gammopathy , ie an overproduction of one type of antibody. To clarify the question of whether it is a monoclonal or a polyclonal antibody propagation , an immunofixation electrophoresis must be connected. The quantitative determination of the individual immunoglobulin isotypes ( IgG , IgM , IgA ; possibly also IgE , IgD ) is then recommended .
If “shoulder formation” occurs in the γ fraction, it is cirrhosis of the liver . Due to the reduced albumin formation in liver cirrhosis, the immunoglobulin fraction can be increased in a compensatory manner in order to maintain the oncotic pressure in the vascular system.
literature
- BJ DAVIS: DISC ELECTROPHORESIS. II. METHOD AND APPLICATION TO HUMAN SERUM PROTEINS. In: Annals of the New York Academy of Sciences. Volume 121, December 1964, pp. 404-427, PMID 14240539 .
Individual evidence
- ↑ SR Vavricka, E. Burri, C. Beglinger, L. Degen, M. Manz: Serum protein electrophoresis: an underused but very useful test. In: Digestion. Volume 79, number 4, 2009, pp. 203-210, doi: 10.1159 / 000212077 , PMID 19365122 .
- ↑ a b c Lothar Thomas: Laboratory and diagnosis . 6th edition. TH-Books Verlagsgesellschaft mbH, Frankfurt / Main 2005, ISBN 3-9805215-5-9 , 18.3 Serum Protein Electrophoresis, p. 934-938 .
