Protein Fractions of Serum
Apr 25, 2018
To separate protein fractions, a method of electrophoresis is usually used, based on the different mobility of whey proteins in an electric field. This study is diagnostic more informative than the determination of only the total protein or albumin. On the other hand, the study of protein fractions makes it possible to judge the protein excess or deficiency characteristic of a disease only in its most general form. The fractions of proteins of blood serum, released by electrophoresis, are presented in the table. Analysis of the results of protein electrophoresis makes it possible to establish at the expense of which fraction the patient has an increase or decrease in the concentration of the total protein, and also to judge the specificity of the changes characteristic for this pathology.
Table Protein Fractions Serum in Normal
Table Protein Fractions of Serum Normal
Changes in Albumin Fraction. Increases in the absolute content of albumins, as a rule, are not observed.
Changes in the fraction of a1-globulins. The main components of this fraction include a: -antitrypsin, aglypoprotein, acid aglycoprotein.
■ Increase in the fraction of agglobulins observed in acute, subacute, exacerbation of chronic inflammatory processes;lesions of
liver;all processes of tissue decay or cell proliferation.
■ Reduction of the fraction of a1-globulins is observed with a deficiency of a-antis-trypsin, hypo-alipoproteinemia.
Changes in the fraction of a2-globulins.a2-Fraction contains a2-macroglobulin, haptoglobin, apolipoproteins A, B( apo-A, apo-B), C, ceruloplasmin.
■ An increase in the fraction of a2-globulin is observed in all types of acute inflammatory processes, especially with marked exudative and purulent character( pneumonia, empyema of the pleura, other types of purulent processes);diseases associated with the involvement of connective tissue in the pathological process( collagenoses, autoimmune diseases, rheumatic diseases);malignant tumors;in the stage of recovery from thermal burns;nephrotic syndrome;hemolysis of blood in vitro.
■ Reduction of a2-globulin fraction is observed in diabetes mellitus, pancreatitis( sometimes), congenital jaundice of mechanical origin in newborns, toxic hepatitis.
The α-globulin is the bulk of the acute phase proteins. The increase in their content reflects the intensity of the stress reaction and inflammatory processes in the listed types of pathology.
Changes in the fraction of p-globulins. P-Fraction contains transferrin, hemopexin, complement components, Ig and lipoproteins( LP).
■ An increase in the fraction of p-globulin is detected in primary and secondary hyperlipoproteinaemia( HLP)( especially type II), liver disease, nephrotic syndrome, bleeding stomach ulcer, hypothyroidism.
■ Reduced values of the content of p-globulins are detected with hypo-P-lipoproteinemia.
Changes in the fraction of y-globulins. The γ-fraction contains Ig( IgG, IgA, IgM, IgD, IgE), so an increase in the content of γ-globulins is noted during the reaction of the immunity system when the development of AT and autoantibodies occurs: in viral and bacterial infections, inflammation, collagenoses, tissue destructionand burns. Significant hypergammaglobulinemia, reflecting the activity of the inflammatory process, is characteristic of chronic active hepatitis and cirrhosis of the liver. An increase in the fraction of y-globulin is observed in 88-92% of patients with chronic active hepatitis( in 60-65% of patients it is very pronounced - up to 26 g / l and above).Almost the same changes are noted in patients with highly active and far-reaching cirrhosis of the liver, and often the content of y-globulins exceeds the albumin content, which is considered a poor prognostic sign.
For certain diseases, an increased synthesis of proteins falling into the fraction of y-globulins is possible, and pathological proteins appear in the blood - paraproteins, which are detected by electrophoresis. To clarify the nature of these changes, immunoelectrophoresis is necessary. Similar changes are noted in myeloma, Waldenström's disease.
An increase in blood levels of y-globulin is also observed in rheumatoid arthritis, SLE, chronic lymphocytic leukemia, endothelioma, osteoarcoma, candidamycosis.
Reduction of y-globulin content is primary and secondary. There are three main types of primary hypogammaglobulinemia: physiological( in children aged 3-5 months), congenital and idiopathic. The causes of secondary hypogammaglobulinemia can be numerous diseases and conditions leading to the depletion of the immune system.
A comparison of the directionality of changes in the content of albumins and globulins with changes in total protein content suggests that hyperproteinemia is more often associated with hyperglobulinemia, while hypoproteinemia is usually due to hypoalbuminemia.
In the past, the calculation of the albumin-globulin coefficient, that is, the ratio of the fraction of albumins to the value of the globulin fraction, was widely used. Normally, this figure is 2.5-3.5.In patients with chronic hepatitis and cirrhosis of the liver, this coefficient is reduced to 1.5 and even to 1 due to a decrease in albumin content and an increase in the fraction of globulins.
In recent years, more attention has been paid to determining the content of prealbumins, especially in severe resuscitation patients who are on parenteral nutrition. Decrease in the concentration of pre-albumins - an early and sensitive test of protein deficiency in the patient's body.