Lecture 9 9/12/24 Flashcards
What is the most abundant component of plasma?
protein
What are the functions of plasma proteins?
-blood coagulation
-maintaining oncotic pressure
-host defense
-transport of substances
-regulation of cellular metabolism
What are the two major categories of plasma proteins?
-albumin
-globulins
What are the characteristics of albumin?
-one of the smallest proteins
-single most abundant protein
-synthesized in the liver
-accounts for 75% of colloidal osmotic pressure
-carrier molecule, especially for calcium
Which proteins are included as globulins?
-immunoglobulins
-acute phase proteins
-complement proteins
-lipoproteins
What are the characteristics of globulins?
-all non-albumin proteins
-typically combined with other substances
-mostly synthesized by liver
-immunoglobulins are secreted by plasma and B cells
What are the characteristics of acute phase proteins?
-change in conc. by >25% in response to inflammatory cytokines
-increase in conc. if they are positive acute phase proteins
-decrease in conc. if they are negative acute phase proteins
What is the major negative APP?
albumin
What is the major positive APP in dogs and pigs?
C reactive protein
What is the major positive APP in cats and horses?
serum amyloid A
What is the major positive APP in ruminants?
haptoglobin
What are the characteristics of the acute phase response?
-positive APPs increase and decrease quickly
-positive APPs typically increase prior to presence of inflammatory leukogram and persist until inflammation resolves
What are the characteristics of plasma?
-liquid portion of unclotted blood
-contains all proteins
-must be collected with anticoagulant
What are the characteristics of serum?
-liquid portion of clotted blood
-contains all proteins except fibrinogen
What are the characteristics of total protein refractometry?
-estimation of protein in plasma
-expressed as a concentration (g/dL)
-reported as part of CBC
-light refraction is proportional to solids in solution
What is the assumption made with TP refractometry?
the concentrations of glucose, electrolytes, urea, and lipids are normal
What are the interferences for TP refractometry?
-hyperglycemia
-increased urea
-hypercholesterolemia
-lipemia
-excess EDTA in blood
How do hyperbilirubinemia and hemolysis impact TP refractometry?
make the demarcation difficult to read
What are the characteristics of fibrinogen by heat precipitation?
-crude measurement used in large animal
-detects hyperfibrinogenemia only
-more sensitive to inflammation than leukogram changes
-reported on CBC
-take the measurement from pre-heating and subtract measurement from post-heating
What are the characteristics of TP via spectrophotometry?
-reported on chem profile
-expressed as concentration (g/dL)
-not sensitive enough for low protein fluids
-does not account for fibrinogen unless heparinized plasma is used
How is albumin typically measured?
via spectrophotometry that is reported on the chem profile
How are globulins reported on the chem profile?
indirect calculation using TP - albumin
What are the characteristics of fractionate globulins?
-identified via protein electrophoresis
-indicated when patient has moderate to marked hyperglobulinemia
-determines inflammatory response vs neoplasia
What are the principles of protein electrophoresis?
-separates proteins by size, shape, and charge
-area under each peak is proportional to the % of the fraction in serum
-numerical results provide absolute values for each fraction
-must examine the gel tracing for interpretation
What is dysproteinemia?
presence of normal protein at abnormal concentration
What are the mechanisms of dysproteinemia?
-relative/shifting of water
-decreased production
-increased production
-loss
How does a nonselective dysproteinemia differ from a selective dysproteinemia?
-nonselective: both albumin and globulin are affected in the same direction
-selective: only albumin or globulin is affected or both are affected in opposite directions
What are the characteristics of nonselective hyperproteinemia?
-most common cause is concurrent increase in albumin and globulin due to dehydration
-typically accompanied by increased HCT
-relative increase due to water loss
What are the general characteristics of nonselective hypoproteinemia?
-often caused by overhydration or hemodilution
-can be caused by IV fluid administration or edematous disorders
What are the characteristics of nonselective hypoproteinemia caused by protein losing enteropathy?
-intestinal disease prohibits absorption or transport of proteins, resulting in loss in the feces
-hypoproteinemia occurs when rate of protein loss exceeds ability of liver and B cells to produce proteins
What are the characteristics of nonselective hypoproteinemia caused by effusive disease?
-vasculitis results in extravasation of proteins into interstitial space
-pleuritis and peritonitis lead to extravasation of proteins into pleural and peritoneal cavities
What are the characteristics of nonselective hypoproteinemia caused by protein losing dermatopathy?
-thermal or chemical burn can result in plasma proteins oozing out of vessels
-globulins may increase with inflammation
What are the potential causes of hypoalbuminemia due to decreased production?
-inflammation
-hepatic failure
-starvation/cachexia
What are the potential causes of hypoalbuminemia due to increased loss?
-protein losing nephropathy
-GI parasites
What are the characteristics of hypoalbuminemia due to inflammation?
-albumin is major negative acute phase protein
-increased production of positive APPs requires decreased albumin production to conserve amino acids
-often accompanied by increased globulins
-may be accompanied by inflammatory leukogram
-most common dysproteinemia
What are the characteristics of hypoalbuminemia due to hepatic insufficiency?
-must lose 50-80% of liver function
-albumin and globulin production decrease, but immunoglobulin production can keep globulin values normal
-other signs of hepatic insufficiency present
What are the characteristics of hypoalbuminemia due to starvation?
-starvation or cachectic states result in decreased nutrient intake and increased protein degradation
-hypoproteinemia due to low albumin only
What are the characteristics of hypoalbuminemia due to protein-losing nephropathy?
-albumin is small enough to pass through damaged glomerular membranes
-will see proteinuria and increased urine protein: creatinine ratio
-hypoglobulinemia can occur in severe cases
-may see other evidence of renal insufficiency
What are the characteristics of hypoglobulinemia?
-typically caused by decreased immunoglobulins
-often due to failure of transfer of passive immunity or immune deficiency
What are the characteristics of hyperglobulinemia?
caused by chronic antigenic stimulation or B-lymphocyte neoplasia
Which fraction do the positive acute phase proteins migrate to during acute inflammation?
alpha2 fraction
What are the characteristics of polyclonal gammopathy?
-broad-based peaks in beta and gamma globulins
-secondary to prolonged antigenic stimulation
-concurrent hypoalbuminemia is common
What are the characteristics of monoclonal gammopathy?
-tall narrow peak in beta or gamma fraction
-immunoglobulin secreted by neoplastic proliferation of B cell or plasma cell (multiple myeloma, extra-medullary plasmacytoma)
-some diseases can mimic monoclonal gammopathy (Ehrlichia)
What are the characteristics of nonselective hypoproteinemia caused by blood loss?
-hemorrhage results in blood volume loss
-compensatory fluid shifts from extravascular to intravascular space
-hemodilution causes hypoproteinemia and anemia
