360 - Serum Proteins Flashcards
T or F. SPE is a routine test
F!
Indications for ordering SPE include:
Suspected multiple myeloma or Waldenström’s macroglobulinemia,
Suspected primary amyloidosis
New-onset anemia associated with renal failure or insufficiency and bone pain
Hypercalcemia
Rouleaux formations noted on PBS
Renal insufficiency with associated serum protein elevation
Unexplained pathologic fracture or lytic lesion identified on a radiograph
Monoclonal free light chain proteinuria
albumin
- liver
- neg APR
- binds and transports many substances = acidic drugs, bilirubin, calcium
- controls colloidal oncotic pressure
- DECREASED in liver disease, nephrotic syndrome, and acute + chronic inflammation
- a relative decrease in multiple myeloma
alpha1-antitrypsin
- acute phase reactant
- synthesized by the liver
alpha1-lipoproteins
- HDL & apolipoprotein A-1
- transports cholesterol and fat-soluble vitamins
alpha1-acid glycoprotein
o acute phase reactant
o binds basic and lipophilic drugs
o produced by liver
alpha2-macroglobulin
o synthesized by the liver
o markedly increased in nephrotic syndrome
o decreased in pancreatitis and prostate cancer
haptoglobin (alpha2)
o acute phase reactant
o synthesized by the liver
o binds and transports free hemoglobin
o increased in nephrotic syndrome + inflammation
o decreased in intravascular hemolysis and liver disease
ceruloplasmin (alpha2)
o acute phase reactant
o synthesized by the liver
o binds 90% of the body’s copper
o increases observed in inflammation, severe infection
o decreases observed in nephrotic syndrome, liver disease, malnutrition
beta-lipoproteins
o synthesized the liver
o VLDL and LDL; transports cholesterol, phospholipids and hormones
transferrin
o synthesized by the liver
o a negative acute phase reactant
o transports iron
o increased in iron-deficient anemia
o decreased in inflammation, liver disease, protein malnutrition, nephrotic syndrome
beta2-microglobulin
o the light or β chain of the HLAs
o increased in renal failure, inflammation, and tumours
fibrinogen
o seen in plasma samples
o synthesized by the liver
o it is an acute phase reactant and a coagulation protein
C3, C4 (beta)
o complement factors
o decreased in SLE, nephrotic syndrome, chronic renal and liver disease
o increased in acute inflammation
immunoglobulins (Gamma)
o produced by plasma cells
o involved in humoral immunity
o increased in infection, autoimmune diseases, myeloma
o decreased in nephrotic syndrome, burns or inherited deficiencies
C-reactive protein
o synthesized by the liver
o acute phase reactant
o CRP activates the classical complement pathway
a sensitive method for the detection and identification of monoclonal components in the serum or urine
Immunofixation electrophoresis (IFE)
this is a follow-up test for monoclonal gammopathies or M-peaks
IFE
How does IFE work?
- serum sample is separated by agarose gel electrophoresis,
- different antiserums
added to the appropriate lanes - antibody-antigen complexes precipitate out; the immune
precipitate is trapped within the gel matrix, and all the other non-precipitated proteins can be removed
by washing the gel - gel can then be stained for identification of the proteins
What is a paraprotein?
a monoclonal immunoglobulin, polymers of immunoglobulin or light chain (kappa or lambda) present in the blood or urine; a clonal population of mature B cells (plasma cells) produces it
these are used to detect and identify paraproteins?
Serum protein electrophoresis and immunofixation electrophoresis
Paraproteins can cause…
SPE monoclonal bands or M-band
Clinical identification of
paraproteins may be useful in the detection and monitoring of …
plasma cell and B lymphocyte disorders
Paraproteins may be found in patients many disorders including…
multiple myeloma,
plasmacytoma,
lymphoproliferative disorders,
autoimmune disease,
liver diseases,
bacterial infections
Majority of paraproteins are associated with these
multiple myeloma and solitary plasmacytoma (60%)
~15% of paraproteins are associated with these
lymphomas, CLL, Waldenströms’ macroglobulinemia
T or F. A quarter of paraproteins are not associated with a disease state and are grouped as monoclonal gammopathies of
undetermined significance (MGUS)
T!
How are paraproteins an unpredictable source of interference in the lab?
they may aggregate or precipitate to interfere in spectrophotometric analysis and block sample probe, particularly in hematology
What are Bence Jones proteins?
also called monoclonal free light chains (MFLC)
These small proteins are
found in the blood and urine of approximately 20% of patients with multiple myeloma
describe macrogloubulins
- molecular weight >/= 1 000 000 Dalton
- cause an increase in serum viscosity
- include IgM (10-30%) and alpha2-macroglobulin (70%)
- seen in Waldenström’s macroglobulinemia (increase in alpha2-macroglobulin)
proteins that precipitate at a temperature below 37°C and dissolve upon warming to body temperature
cryoglobulins
the three types of cryoglobulins:
I – monoclonal immunoglobulin (i.e. IgM)
II – polyclonal immunoglobulins with a monoclonal component (most common)
III – polyclonal immunoglobulins without a monoclonal component
most common cryoglobulin
II - polyclonal with monoclonal component
Cryoglobulinemia is associated with…
lymphoproliferative disorders, autoimmune diseases, infectious
diseases, especially hepatitis C
Cryoglobulin accumulation may lead to…
vasculitis and ischemic injury as they lodge in vessel walls and fix fibrinogen and complement
T or F. Cryoglobulins can falsely
increase the WBC count on the Coulter
T! manual WBC count must be done
This compares the proteins in serum and CSF by electrophoresis and immunofixation
oligoclonal banding
what are oligoclonal bands comprised of?
populations of IgG molecules with the same electrophoretic mobility and are only found in the CSF
sample
- seen in 80-90% of MS patients
T or F. NORMALLY, CSF has less IgG than serum
T!
the IgG index compares the relative amount of IgG in CSF to serum; an increased IgG index indicates intrathecal IgG synthesis
_________ venous occlusion will ________ total protein as blood pools in the vein
Prolonged; increase
The total protein value from a patient lying down will be ____ than in a patient in the upright position as fluid _______ occurs, causing a dilution effect
less; retention
Describe the biuret method:
- peptide bonds react with Cu2+ in alkaline = violet complex
- complex formed between Cu2+ and carbonyl + imine groups of peptide linkage
- the more protein present, the more peptide bonds available for rxn; intensity of colour produced is proportional to amount of protein in sample
- proteins in the sample combine with the reagent to produce an alkaline copper-protein chelate (520/540 nm); directly proportional to total protein concentration in sample
this may be added to maintain solubility of copper in biuret method
tartrate salts
this may be added toas an antioxidant in biuret method
iodine
specimen for biuret method
serum or heparin plasma
- plasma samples generally yield values slightly higher than serum samples
quantitative methods for total proteinq
biuret metod and albumin (?)
quantitative methods for total protein
biuret method and albumin (?)
interference in biuret method
- Gross hemolysis may increase protein values due to the release of cellular elements
- Icterus may slightly affect results
- Lipemic specimens should be avoided
sensitivity of biuret method
- not sensitive enough for urine and CSF
- monoclonal free light chains are underestimated
These can be used to measure albumin
Bromocresol green (more common) and bromocresol purple
@ acidic pH, positively
charged proteins bind to the negatively charged dye
the absorption maximum of the dye shifts when it is bound to albumin
interference in brom green binding to albumin
brom green binds Hb = positive chemical interference in hemolyzed samples
T or F. Bromocresol purple is more specific than Brom green for albumin
T! BUT the assay may be affected by icterus
Specific serum proteins can be quantitated by…
adding antiserum to a specific protein and measuring the antigen-antibody complexes using either immunoturbidimetry or immunonephelometry
increased total protein in serum
dehydration
hyperlipidemia
monoclonal gammopathy
inflammatory rxns
hyperimmunoglobulinemia
decreased total protein in serum
hypogammaglobulinemia
liver disease
burns/hemorrhage
salt retention
nephrotic syndrome
increased total protein in CSF
cerebral hemorrhage
encephalitis
increased serum proteins
meningitis
MS
increased total protein in urine
glomerulonephritis
nephrotic syndrome
pregnancy
pyelonephritis
multiple myeloma
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