What is the protidogram?
L'protein electrophoresis, also referred to as com protein electrophoresis or protidogram, is a particular analytical technique based on the different migration speed of electrically charged particles dispersed in a gelled solution of agarose, under the effect of an electric field applied to the system by means of a pair of electrodes.
In medicine, this test is used to analyze the proteins present in a liquid medium, such as for example blood, blood serum or urine, allowing to quantify their presence also in relation to the other protein components. For this reason, it is called "protein electrophoresis" or "protidogram".
What is the protidogram for?
We can therefore define protein electrophoresis as a "sieve" that allows to divide all the serum or blood proteins on the basis of their speed of migration within the electric field. This speed depends on several factors, including the nature of the applied electric field, the mass, size, charges and shapes of the different protein molecules. A altered protidogram it will reflect protein alterations both in a quantitative and qualitative sense.
The electrophoretic protidogram allows both to quantify the total proteins present in the blood, and to discriminate them on the basis of their migration speed. For this reason, whey proteins can be divided into two main classes: albumin and globulins, the latter divided into alpha globulins, divided into alpha 1 and alpha 2, beta globulins, divided into beta 1 and beta 2, and gammaglobulins.
Total blood protein
This parameter indicates the protein fraction within the blood sample analyzed (protidemia). THE normal values of proteins in circulation are included between 6.4 and 8.3 grams per deciliter (g / dl) of blood.
Low values of proteins they can indicate problems in the kidney, liver or in the metabolism of the gastrointestinal system (malnutrition, celiac disease, Crohn's disease and ulcerative colitis, etc.), but it is possible to find alterations in case of important alterations in the hemodynamics of the organism, as in the case of major hemorrhage, burns covering more than 5% of the body's surface, a state of significant dehydration etc ... High values, on the other hand, are found in inflammatory, acute and chronic states, due to infections (hepatitis viruses, HIV ...) or to neoplastic processes (multiple myeloma in primis).
Physiologically it represents the highest amount of protein present in serum, it is produced by the liver and has many functions, including that of transporting several substances, endogenous and exogenous. There concentration physiological of albumin must be between 3.6 and 5.3 g / dl of blood. This concentration represents 59.1-69.3% of the total protein.
Values of high albumin they indicate good liver health, which is able to produce this protein in greater quantities, even if it has little clinical relevance for the doctor; if the percentage decreases, but not its quantity, it means that the organism is producing one or more proteins, but not albumin (which is the main one). This should guide the physician towards the in-depth diagnosis of some inflammatory diseases or protein producers such as myeloma multiple; if both the concentration and the percentage are found to be decreased, it means that the liver is not working as it should in its protein production. The disease most frequently associated with this type of picture is cirrhosis.
There is a second parameter that can be evaluated: the albumin globulin ratio. As a rule, this ratio is between 1.2 and 1.7. If this ratio is low, it will indicate an underlying overproduction of globulins, as occurs in multiple myeloma (which will increase the production of gammaglobulins) or an underproduction of albumin, as in the case of hepatopathic patients or cirrhotic. To know what the primary problem is, it will be necessary to evaluate the relative concentrations of the various globulins and of the albumin itself to understand what is at the basis of the alteration.
Alpha 1 globulins
To the group of alpha1-globulins belong numerous proteins, among which the main ones are: alpha1-antitrypsin, alpha1-antichimotrypsin, alpha1-acid glycoprotein, serum amyloid A (SAA) and alpha1-lipoprotein.
Tests for this group of proteins are called normal if theirs quantity is including between 0.2 and 0.4 g / dl of blood and if theirs concentration turns out to be between 2 and the 3.5%.
If a picture is presented with a decrease in its percentage or quantity, the clinical significance is almost nil, except that the liver, for some reason, no longer produces this category of proteins; if, on the other hand, one of the two parameters is increased with respect to physiological values, it means that an inflammatory process is underway within the organism, such as chronic inflammatory diseases or tumors, or infectious.
Alpha 2 globulins
To the group of alpha 2 globulins belong proteins such as haptoglobin, major urinary proteins, alpha2-macroglobulin, ceruloplasmin, thyroid-binding globulin (TBG), alpha2-antiplasmin, protein C, alpha2-lipoprotein and angiotensinogen
The physiological levels of this group of proteins are defined normal if their concentration is between 0.41-0.90 g / dl of blood and whether the percentage is in range 6.1-11.2%.
Also in this case, the finding of one (or both values) of the two parameters lower than the physiological ones does not correlate with any specific disease, but indicates the presence of hemolysis; the appearance, on the other hand, of an increase in the concentration and / or relative percentage of the protein, indicates the presence of an acute or chronic inflammatory-infectious picture in progress within the organism.
To the group of beta globulins belong proteins such as beta-2 microglobulin, plasminogen, angiostatins, properdin, sex hormone binding globulin and transferrin. On the electrophoretic trace they are divided into two bands, beta 1 globulins and beta 2 globulins, based on electrophoretic motility.
Tests for this protein are considered normal if the serum concentration is found to be between 0.56-1 g / dl of blood and the relative percentage is within the range 6.3-12.1%.
The decrease of one of the parameters has no pathological significance, while the severe decrease of both can be an indication of malnutrition, of a disease neoplastic, including lymphomas and leukemias, or some autoimmune diseases, such as Systemic Lupus Erythematosus (SLE) and scleroderma; the increase in values may indicate the presence of an anemia in progress, as this group includes transferrin, which tends to increase when the body's iron reserves are low. There are, however, some cases in which high values of this parameter are associated in the case of cholesterol high and / or in the presence of multiple myeloma.
Within this group we find all the immunoglobulins (IgM, IgG, IgA, IgD, IgE) which are produced by our body to respond to inflammatory processes caused by endogenous and exogenous factors.
The values of this group of proteins are considered physiological if the concentration turns out to be between 0.68 and 1.5 g / dl of blood and if the percentage relative to this protein is between 9.8 and 20%.
The finding of values lower than the physiological ones (hypogammaglobulinemia) indicates a reduction in the production of antibodies due to the absence of any type of inducing stimulus, which could be associated with a state of good health, or because the production of these components is reduced due to an underlying process, as in the case of syndrome Cushing's, kidney failure, septicemia and AIDS; if we find values of high gamma globulin, Numerous causes need to be considered, including MGUS; monoclonal and / or polyclonal gammapathy; cirrhosis of the liver and hepatitis (A, B, C); some autoimmune diseases (Hashimoto's thyroiditis), some viral infections (mononucleosis, chicken pox) and allergies.
Why the exam is performed
Whey protein electrophoresis is prescribed as exam of routine or it is requested in the context of specific clinical analyzes when there is the presence of a symptomatology that suggests the presence of a liver disease (cirrhosis, liver failure), a renal disease (acute or chronic renal failure), an autoimmune disease or haematological (such as leukemia, lymphoma, multiple myeloma, Waldenstrom's macroglobulinemia or primary amyloidosis). Among others symptoms, we recall the most important and most frequent:
- Anemia, back pain, bone pain, fatigue, weakness, nausea, and / or constipation not explained by other diseases;
- Unexplained fracture;
- Important and unexplained weight loss;
- Hypercalcemia due to possible neoplastic disease;
- Unexplained peripheral neuropathy;
- Kidney failure;
- Unexplained proteinuria and / or Bence Jones proteinuria;
Preparation and execution of the exam
Normally no specific preparation is required before the test, if not the one common to all blood tests (fasting from the previous evening, usual diet, any type of physical exercise in the previous 24-48 hours and avoiding, as far as possible, taking drugs). A simple blood sample is taken, most frequently in the morning, and placed inside the electric field, which will determine the migration of the proteins as previously explained.
Factors affecting the measurement
There are some reasons that can prevent the correct execution of the exam or make the results obtained not assessable:
- Assumption of drugs: it was found that the chronic intake of some drugs for diseases already present can significantly alter the test result. Among others, we mention chlorpromation, cortisone, isoniazid, neomycin, phenacemide, salicylates such as aspirin, sulfonamides such as Bactrim and tolbutamide. Other related drugs are endogenous hormone agonists, such as estrogen, male sex hormones (androgens), insulin and growth hormones (Growth Hormone - GH);
- The concomitant presence of injuries or infections at the time of collection it can mask any alterations in the protein ratios in the serum
- The rest to extended bed, as in the case of a long hospitalization or in comatose patients, it can lead to an alteration especially in the relationships between proteins, in particular there is an increased relative production of gamma globulins compared to that of albumin.
- The chronic diseases, especially the intestinal ones, as they interfere with the assimilation and metabolism processes especially of proteins, leading to an imbalance and an alteration of the serum protein electrophoresis values.
- The presence of a pregnancy temporarily alters both the concentration of proteins, which will inevitably be reduced due to the increase in the number of functions to be performed due to the presence of the fetus in the womb and due to the change in the body's hormonal structure due to pregnancy, and intercourse between the proteins themselves.