**5.1. Serum protein pattern variations related to non-pathological conditions**

Variations in the serum protein profile and shifts in albumin and globulin concentrations may occur not only under pathological, but also under physiological conditions [102]. Animal age is one of these important factors that may affect the concentrations of the different serum protein fractions or their electrophoretic pattern [103]. It has been shown in young and adult cattle [228], where the most important age-related differences were observed in the α- and γ-globulin fractions. While the values of α<sup>1</sup> -globulins were higher in calves, the adult animals had higher γ-globulin concentrations. In particular, it has been stated that the most important changes occur in the first month of the life of calves, and are associated with the changes in nutrition and adaptation processes during the neonatal period [229]. The total serum proteins and γ-globulin concentrations increase rapidly 1 day after the intake of colostrum, and then decrease gradually till the end of the first month of age. According to Hammon et al. [230], the concentrations of total proteins in the serum are very low at birth, due to the minimal quantities of immunoglobulins but, it increases during the first 24 hours of life as a result of the intestinal absorption of proteins (particularly immunoglobulins) from colostrum. On the other hand, the concentrations of albumin decrease 1 day after colostrum intake, with a subsequent gradual increase from day 2 till the end of the first month of life. At birth, calve's alpha<sup>1</sup> -globulins comprise almost 30% of total proteins, but their concentrations decreased approximately by 50% at 1 day after birth, with a further decrease up to day 30 of life [229]. In the absolute concentrations of α<sup>1</sup> -globulins, a temporary slight increase after birth has been observed with a subsequent gradual decrease. The delivery is surely a stressful situation for the offspring and it could typically be expressed by higher concentrations of acute-phase proteins at birth, which migrate into this fraction [148]. The acute-phase response may be then substituted by the following increase of the IgG concentrations from the colostrum. Acutephase proteins are produced mainly by the liver, which is less mature in newborn than in young or adult animals. Thus, the most of the acute-phase proteins have lower concentrations at birth than in the next days [231]. Similarly, large amounts of α-globulins were observed in lambs during the first month of life [232].

also present in renal diseases and nephrotic syndrome, in which there is an increased loss of this protein in urine caused by glomerular damage [244]. Moreover, low albumin concentrations may indicate chronic malnutrition, inadequate protein intake, or being associated with gastrointestinal diseases, internal parasitism and protein losing enteropathy [245]. On the other hand, serum albumin is the major negative acute-phase protein and its synthesis may

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Rarely, a serum protein anomaly called bisalbuminemia may be observed on the electrophoretogram. Bisalbuminemia is characterized by the occurrence of a bicuspid electrophoretic pattern in the albumin fraction, where albumin produces two heads (equally staining bands or bands of unequal intensity) [247]. In this abnormality, albumin may either have increased (fast type variants) or decreased electrophoretic mobility (slow type variants) [248]. In humans, the presence of bisalbuminemia have been described in some pathological conditions, including chronic renal diseases, nephrotic syndrome, diabetes mellitus, pancreatic disease or Alzheimer's disease [249]. In ruminants, bisalbuminemia was not yet found. According to Vavricka et al. [76], the presence of bisalbuminemia may be caused by increased mobility of albumin due to its binding to bilirubin, non-esterified fatty acids, penicillin or

The increased concentration of albumin in the serum is called hyperalbuminemia, which may be observed in cases of severe dehydration. However, hyperalbuminemia was recorded also

Increases in the globulin fractions may be frequently seen on serum protein electrophoretograms. Since many acute-phase proteins belong to the alpha-globulin fraction, increase in

eases caused by the activation of the host inflammatory responses [71]. Increased α-globulins

cally increases in patients with nephrotic syndrome as a result of the increased synthesis of

unable to pass through glomeruli and therefore it remains in the bloodstream [253]. Decreases

disorder in humans and even more rare in animals, but in ruminants, it was not yet detected

haptoglobin from this fraction binds with the free hemoglobin released from the destroyed red blood cells, forming haptoglobin-hemoglobin complexes that are rapidly removed by phagocytes [76]. On the other hand, the inflammatory conditions that develop in association with hemolytic anemia leads to an increase of haptoglobin concentration that may induce an

Some acute-phase proteins migrate into the β-region. Thus, several inflammatory diseases and infections may be accompanied also by increases in the β-fraction as a result of the elevated

well as in calves affected by respiratory diseases [251, 252]. The α<sup>2</sup>









be markedly reduced during the acute-phase response [246].

acetylsalicylic acid.


(predominantly α<sup>1</sup>

[254]. Similarly, the α<sup>2</sup>

the α<sup>1</sup>

α2

in the α<sup>1</sup>

increase of α<sup>2</sup>

in dogs with hepatocellular carcinoma [250].


*5.2.2. Changes in the globulin fractions*

Pregnancy and lactation are further factors that may influence the concentrations of albumin and globulin fractions. Variations in the serum protein profile were found in ewes during the pregnancy and lactation, as well as in periparturient goats [233–235]. Changes in the concentrations of protein fractions during the last phase of pregnancy and early *post-partum* were recorded also in dairy cows [236]. Lower concentrations of total serum proteins were found by Grünberg et al. [237] in cows around parturition than outside the parturient period and in the following stages of lactation. These changes may be associated with the transfer of immunoglobulins from the bloodstream to the mammary gland for the synthesis of colostrum [238]. The results of Piccione et al. [235, 239] showed increasing values of α-globulins in dairy cows and ewes *post-partum*, which were probably related to the higher concentrations of the acute-phase proteins in response to the processes occurring around the time of parturition.

The concentrations of serum proteins may be influenced also by hormonal changes and stress. Stress may cause a decrease of serum protein and albumin concentrations, but often may be accompanied by an increase of the α<sup>2</sup> -globulin fraction associated with the acute-phase response [7].

### **5.2. Pathological serum protein pattern: dysproteinemias**

A wide variety of diseases can cause changes in the serum protein pattern [240]. The serum protein electrophoresis is a very important technique for the evaluation of these abnormalities and the nature of the hyperproteinemia or hyperglobulinemia [241]. The protein electrophoresis may be very useful when routine investigations are not effective for making medical decisions, providing the basis for further specific laboratory analyses [22, 242].

#### *5.2.1. Changes in the albumin fraction*

The decrease of the concentrations of albumin is one of the most frequently occurring types of dysproteinemias. Hypoalbuminemia can be caused by decreased production due to liver diseases such as chronic hepatitis, cirrhosis, or liver failure [243]. Hypoalbuminemia may be also present in renal diseases and nephrotic syndrome, in which there is an increased loss of this protein in urine caused by glomerular damage [244]. Moreover, low albumin concentrations may indicate chronic malnutrition, inadequate protein intake, or being associated with gastrointestinal diseases, internal parasitism and protein losing enteropathy [245]. On the other hand, serum albumin is the major negative acute-phase protein and its synthesis may be markedly reduced during the acute-phase response [246].

Rarely, a serum protein anomaly called bisalbuminemia may be observed on the electrophoretogram. Bisalbuminemia is characterized by the occurrence of a bicuspid electrophoretic pattern in the albumin fraction, where albumin produces two heads (equally staining bands or bands of unequal intensity) [247]. In this abnormality, albumin may either have increased (fast type variants) or decreased electrophoretic mobility (slow type variants) [248]. In humans, the presence of bisalbuminemia have been described in some pathological conditions, including chronic renal diseases, nephrotic syndrome, diabetes mellitus, pancreatic disease or Alzheimer's disease [249]. In ruminants, bisalbuminemia was not yet found. According to Vavricka et al. [76], the presence of bisalbuminemia may be caused by increased mobility of albumin due to its binding to bilirubin, non-esterified fatty acids, penicillin or acetylsalicylic acid.

The increased concentration of albumin in the serum is called hyperalbuminemia, which may be observed in cases of severe dehydration. However, hyperalbuminemia was recorded also in dogs with hepatocellular carcinoma [250].
