Clinical Chemistry (Proteins and Tumor Markers)

Question 1

Proteins, carbohydrates, and lipids are the three major biochemical compounds of human metabolism. What is the element that distinguishes proteins from carbohydrate and lipid compounds?

A. Carbon
B. Hydrogen
C. Oxygen
D. Nitrogen

Answer 1

D. Nitrogen

The three major biochemical compounds
that exert primary roles in human intermediary
metabolism are proteins, carbohydrates, and
lipids. The presence of nitrogen in all protein
compounds distinguishes proteins from carbohydrates and lipids. Protein compounds contain
approximately 16% nitrogen. Although there are
only 20 common a-amino acids that are found in
all proteins and a total of 40 known amino acids,
a protein compound may contain from fifty to
thousands of amino acids. The uniqueness of
any protein is dictated by the number, type, and
sequencing of the a-amino acids that compose
it. The a-amino acids are linked to each other
through peptide bonds. A peptide bond is
formed through the linkage of the amino group
of one amino acid to the carboxyl group of
another amino acid.

Question 2

Proteins may become denatured when subjected to mechanical agitation, heat, or extreme chemical treatment. How are proteins affected by denaturation?

A. Alteration in primary structure
B. Alteration in secondary structure
C. Alteration in tertiary structure
D. Increase in solubility

Answer 2

C. Alteration in tertiary structure

A variety of external factors, such as mechanical agitation, application of heat, and extreme chemical treatment with acids or salts, may cause the denaturation of proteins. When proteins are
denatured, they undergo a change in their tertiary
structure. Tertiary structure describes the appearance of the protein in its folded, globular form. When the covalent, hydrogen, or disulfide bonds are broken, the protein loses its shape as its polypeptide chain unfolds. With the loss of this tertiary structure, there is also a loss in some of the characteristic properties of the protein. In general, proteins will become less soluble, and enzymes will lose catalytic activity. Denaturation by use of chemicals has been a useful laboratory tool. The mixing of serum proteins with sulfosalicylic acid or trichloroacetic acid causes the precipitation of both the albumin and globulin fractions. When albumin is placed in water, dilute salt solutions, or moderately concentrated salt solutions, it remains soluble. However, the globulins are insoluble in water but soluble in weak salt solutions. Both the albumins and globulins are insoluble in concentrated salt solutions. Primary structure refers to the joining of the amino acids through peptide bonds to form polypeptide chains. Secondary structure refers to the twisting of more than one polypeptide chain into coils or helices.

Question 3

What is the basis for the Kjeldahl technique for the determination of serum total protein?

A. Quantification of peptide bonds
B. Determination of the refractive index of proteins
C. Ultraviolet light absorption by aromatic rings at 280 nm
D. Quantification of the nitrogen content of protein

Answer 3

D. Quantification of the nitrogen content of protein

Although the Kjeldahl technique for the determination of protein nitrogen is too cumbersome for use in routine testing, it is considered
to be the reference method of choice to validate
materials used with the biuret method. The Kjeldahl technique is based on the quantification of the nitrogen content of protein. It is estimated that the average nitrogen content of protein is
16% of the total weight. In the Kjeldahl technique, protein undergoes a digestion process with sulfuric acid through which the nitrogen
content of the protein is converted to ammonium ion. The ammonium ion in turn may be reacted with Nessler’s reagent, forming a colored product that is read spectrophotometrically, or the ammonium ion may undergo distillation, liberating ammonia that is titrated

Question 4

When quantifying serum total proteins, upon what is the intensity of the color produced in the biuret reaction dependent?

A. Molecular weight of the protein
B. Acidity of the medium
C. Number of peptide bonds
D. Nitrogen content of the protein

Answer 4

C. Number of peptide bonds

A commonly used method to quantify serum total proteins is the biuret procedure. The biuret reaction is based on the complexing of cupric ions in an alkaline solution with the peptide linkages
of protein molecules. Because the amino acids of all proteins are joined together by peptide bonds, this method provides an accurate quantification of the total protein content of serum. The greater the amount of protein in a specimen, the greater will be the number of available peptide bonds for reaction and the more intense the colored reaction will be. In the biuret reaction, the intensity of the reddish violet color produced is proportional to the number of peptide bonds present. Generally, one cupric ion complexes with four to six peptide linkages. However, a colored product may be formed when the cupric ion links through coordinate bonds with at least two peptide linkages,
with the smallest compound able to react being the tripeptide. Therefore, not only will proteins contribute to the formation of the colored product, but so, too, will any tripeptides and polypeptides
present in a serum sample.

Question 5

Which of the following reagents can be used to measure protein in cerebrospinal fluid?

A. Biuret
B. Coomassie brilliant blue
C. Ponceau S
D. Bromcresol green

Answer 5

B. Coomassie brilliant blue

The concentration of total protein in cerebrospinal fluid (CSF) is 15^5 mg/dL. Such a low level of protein requires a method with sufficient sensitivity such as Coomassie brilliant blue. Turbidimetric methods can also be used to quantify protein in CSF. Neither biuret nor Ponceau S has the sensitivity needed, and bromcresol green measures only albumin and does not react with the globulins

Question 6

Which disorder is not associated with an elevated protein level in cerebrospinal fluid?

A. Bacterial meningitis
B. Multiple sclerosis
C. Cerebral infarction
D. Hyperthyroidism

Answer 6

D. Hyperthyroidism

CSF, an ultrafiltrate of blood plasma, is made in the choroid plexus of the ventricles of the brain. Protein quantification is among the
tests generally ordered on CSF; other tests include glucose, culture and sensitivity, and differential cell count. The reference range for CSF protein is 15-45 mg/dL. CSF protein may bequantified using turbidimetric (e.g., sulfosalicylic acid and benzethonium chloride) or dye binding methods (e.g., Coomassie brilliant blue). Elevated levels of CSF protein are found in such disorders as bacterial, viral, and fungal meningitis; multiple sclerosis; neoplasm; disk herniation; and cerebral infarction. Low levels of CSF protein are found in hyperthyroidism and in CSF leakage from the central nervous system.

Question 7

Which term describes a congenital disorder that is characterized by a split in the albumin band when serum is subjected to electrophoresis?

A. Analbuminemia
B. Anodic albuminemia
C. Prealbuminemia
D. Bisalbuminemia

Answer 7

D. Bisalbuminemia

Bisalbuminemia is a congenital disorder that does not exhibit any clinical manifestations. The only sign of this disorder is the splitting of albumin into two distinct bands when serum is subjected to electrophoresis. The extra albumin band may occur either anodically or cathodically to the normal albumin band depending on its speed of migration. The intensity of the two bands when quantified by densitometry may show that the two forms are of equal concentration. In a less common variation the abnormal
albumin band may represent only 10-15% of the total albumin concentration

Question 8

In what condition would an increased level of serum albumin be expected?

A. Malnutrition
B. Acute inflammation
C. Dehydration
D. Renal disease

Answer 8

C. Dehydration

There are no physiological diseases that
cause increased production of albumin by the
liver. Elevated serum albumin is only associated
with dehydration. It is a relative increase that
will return to normal when fluids are administered to alleviate the dehydration. Disorders such as malnutrition, acute inflammation, and
renal disease are characterized by decreased
serum albumin levels.

Question 9

Identification of which of the following is useful in early stages of glomerular dysfunction?

A. Microalbuminuria
B. Ketonuria
C. Hematuria
D. Urinary light chains

Answer 9

A. Microalbuminuria

In renal disease, glomerular or tubular malfunction results in proteinuria. In early stages of glomerular dysfunction, small quantities of albumin will appear in the urine. Because the concentration is so low, urine dipstick assays are unable to detect the presence of such a small quantity of albumin; hence the term “microalbuminuria.”
Annual testing of diabetic individuals for microalbuminuria is recommended, because identification of these low levels of albumin that precede nephropathy would allow for clinical intervention to control blood glucose levels and blood pressure. The reference interval for urinary albumin is less than 30 mg/day. Microalbuminuria
may be quantified using immunonephelometry and enzyme immunoassay.

Question 10

Which of the following is a low-weight protein that is found on the cell surfaces of nucleated cells?

A. C-reactive protein
B. B2-Microglobulin
C. Ceruloplasmin
D. a2-Macroglobulin

Answer 10

B. B2-Microglobulin

B2-Microglobulin is a single polypeptide
chain that is the light chain component of human
leukocyte antigens (HLAs). It is found on the
surface of nucleated cells and is notably present
on lymphocytes. Increased plasma levels of fi2~
microglobulin are associated with renal failure,
lymphocytosis, rheumatoid arthritis, and systemic lupus erythematosus

Question 10

Which glycoprotein binds with hemoglobin to facilitate the removal of hemoglobin by the reticuloendothelial system?

A. Haptoglobin
B. Ceruloplasmin
C. cxpAntitrypsin
D. Fibrinogen

Answer 10

A. Haptoglobin

A. Haptoglobin is a glycoprotein produced mainly by the liver that migrates electrophoretically as an alpha2-globulin. Increased serum concentrations of haptoglobin are seen in inflammatory conditions and tissue necrosis, whereas decreased levels are seen in hemolytic
situations in which there is extensive red blood cell destruction. In the latter situation, haptoglobin binds with free hemoglobin to form a stable complex that may then be removed by the reticuloendothelial system. Because of the size of the haptoglobin-hemoglobin complex, urinary excretion of hemoglobin by the kidney is avoided, thereby preventing the loss of iron by the kidney

Question 11

In a healthy individual, which protein fraction has the greatest concentration in serum?

A. Alpha1-globulin
B. Beta-globulin
C. Gamma-globulin
D. Albumin

Answer 11

D. Albumin

D. The serum proteins are divided into five
principal fractions based on their electrophoretic
mobilities. The five fractions are albumin,
alpharglobulin, alpha2-globulin, beta-globulin,
and gamma-globulin. Albumin constitutes the
largest individual fraction of the serum proteins.
The reference concentration of albumin in
serum ranges between 3.5 and 5.0 g/dL, and the
total globulin concentration is between 2.3 and
3.5 g/dL.

Question 12

Which of the following is an anionic dye that binds selectively with albumin?

A. Amido black
B. Ponceau S
C. Bromcresol green
D. Coomassie brilliant blue

Answer 12

C. Bromcresol green

Bromcresol green (BCG) and bromcresol
purple (BCP) are anionic dyes that bind selectively with albumin without preliminary extraction of the globulins. The nature of the dyes is such that the color of the free dye is different
from the color of the albumin-dye complex so
that the color change is directly proportional to
the concentration of albumin in the specimen.
Although amido black, Ponceau S, and Coomassie brilliant blue are able to bind albumin, they also react with the globulins, thus prohibiting their use in a direct procedure for
quantification of serum albumin.

Question 13

Which total protein method requires copper sulfate, potassium iodide in sodium hydroxide, and potassium sodium tartrate in its reagent system?

A. Kjeldahl
B. Biuret
C. Folin-Ciocalteu
D. Ultraviolet absorption

Answer 13

B. Biuret

Biuret reagent is a combination of copper sulfate, potassium iodide in sodium hydroxide, and potassium sodium tartrate. The copper sulfate is the key to the reaction because it is the cupric ion that complexes with the peptide bonds of protein. To keep the copper in solution until its use, potassium sodium tartrate is employed as a complexing agent, whereas the autoreduction of copper is prevented by potassium iodide.

Question 14

Which of the following plasma proteins is not manufactured by the liver?

A. Albumin
B. Haptoglobin
C. Fibrinogen
D. IgG

Answer 14

D. IgG

The majority of the plasma proteins are manufactured by the liver. Albumin, fibrinogen, and most of the alpha- and beta-globulins are produced by the liver. The immunoglobulins, including IgG, IgA, IgM, IgD, and IgE, are produced by the lymphoid cells.

Question 15

There are five immunoglobulin classes: IgG, IgA, IgM, IgD, and IgE. With which globulin fraction do these immunoglobulins migrate electrophoretically?

A. Alphapglobulins
B. Alpha2-globulins
C. Betapglobulins
D. Gamma-globulins

Answer 15

D. Gamma-globulins

The immunoglobulins, IgG, IgA, IgM, IgD,
and IgE, migrate electrophoretically with the
gamma-globulin fraction. The normal serum
levels of the IgD and IgE classes are so low that
these two immunoglobulins do not normally
contribute to the intensity of the stained gammaglobulin electrophoretic fraction. The primary
component of the gamma fraction consists of
IgG, with IgA and IgM contributing to the intensity of the stained fraction to a lesser degree. In
disease states the concentration relationship
between the immunoglobulins may be significantly altered from the normal.

Question 16

Which immunoglobulin class, characterized by its possession of a secretory component, is found in saliva, tears, and body secretions?

A. IgA
B. IgD
C. IgG
D. IgM

Answer 16

D. IgM

All the immunoglobulins consist of heavyand light-chain polypeptides. The heavy chains
are designated as gamma y, alpha a, mu (x, delta
A, and epsilon e and are specific for the
immunoglobulins IgG, IgA, IgM, IgD, and IgE,
respectively. The light chains are designated as
kappa K and lambda X, with both types being
found in each of the immunoglobulin classes,
although the two light chains attached to a particular set of heavy chains must be of the same type.
Therefore, IgG consists of two heavy chains of
the gamma type and two light chains of either the
kappa or lambda type. The immunoglobulins
IgA, IgD, and IgE have a structure similar to that
of IgG in that they consist of two light chains and
two heavy chains of the respective type. IgM is a
macromolecule with a pentamer type of structure. IgM consists of five sets of two heavy-chain
and two light-chain units, with the basic units
being linked to each other by peptide fragments.

Question 16

Of the five immunoglobulin classes, IgG is the most structurally simple, consisting of how many light chains/heavy chains, respectively?

A. 5/2
B. 1/1
C. 2/5
D. 2/2

Answer 16

A. 5/2

The immunoglobulin class IgA is found in
both plasma and body secretions, with the two
types being differentiated by their sedimentation
coefficients. Plasma IgA has an average sedimentation coefficient of 7S, and secretory IgA has a sedimentation coefficient of US. Secretory IgA is present in saliva, tears, and secretions of nasal, gastrointestinal, and tracheolbronchial origin. Secretory IgA is dimeric in structure and
possesses a glycoprotein secretory component attached to its heavy chains and a J polypeptide. The principal immunoglobulin found in secretions is IgA, with only trace amounts of IgG being present. The presence of IgM, IgD, or IgE in secretions has not been detected.

Question 17

Which immunoglobulin class is able to cross the placenta from the mother to the fetus?

A. IgA
B. IgD
C. IgE
D. IgG

Answer 17

D. IgG

The only immunoglobulin class that is able
to cross the placenta from the mother’s circulation to the fetus is IgG. Therefore, at birth, there
is very little immunoglobulin present in the
infant except for the maternal IgG. After birth, as
the infant comes in contact with antigens, the
levels of IgG, IgA, and IgM slowly increase

Question 18

Which of the following is an acute-phase reactant protein able to inhibit enzymatic proteolysis and having the highest concentration of any of the plasma proteolytic inhibitors?

A. C-reactive protein
B. Haptoglobin
C. a2-Macroglobulin
D. a1-Antitrypsin

Answer 18

D. a1-Antitrypsin

A1-Antitrypsin is an acute-phase reactant protein whose concentration increases in response to
inflammation, a i-Antitrypsin inhibits the selfdestruction of one’s own tissue by forming inactive complexes with proteolytic enzymes. In
this way the enzymes are inhibited, and tissue
destruction through self-digestion is avoided. a-
Antitrypsin has been found to have the highest
concentration in serum of any of the plasma proteolytic inhibitors. It is an effective inhibitor of
the enzymes chymotrypsin, plasmin, thrombin,
collagenase, and elastase. The primary effect of
aj-antitrypsin may be seen in the respiratory tract
and the closed spaces of the body where physiological pH values are maintained, a j-Antitrypsin
is least effective in the stomach and intestines.

Question 19

Which of the following is a copper transport protein that migrates as an alpha2-globulin?

A. Ceruloplasmin
B. Haptoglobin
C. Transferrin
D. Fibrinogen

Answer 19

A. Ceruloplasmin

Ceruloplasmin, a metalloprotein, is the principal transport protein of copper in the plasma. In the plasma, copper is primarily bound to
ceruloplasmin, with only very small amounts of copper bound to albumin or in a dialyzable free state. When subjected to an electric field, ceruloplasmin migrates as an alpha2-globulin

Question 20

Which of the following proteins is normally produced by the fetus but is found in increased amounts in the amniotic fluid in cases of spina bifida?

A. a1-antitrypsin
B. a1-Acid glycoprotein
C. a1-Fetoprotein
D. a2-Macroglobulin

Answer 20

C. a1-Fetoprotein

The liver of a fetus and the yolk sac produce
a protein known as arfetoprotein (AFP). The
concentration of AFP in the blood of a fetus
reaches a maximum concentration at approximately 16 to 18 weeks gestation. Blood levels decline from this point and finally disappear
approximately 5 weeks after birth. In cases of open spina bifida or anencephaly, the fetus leaks large amounts of AFP into the amniotic fluid. By means of an amniocentesis, the amount of AFP
present in the amniotic fluid may be quantified by enzyme-labeled immunoassay and other immunoassay techniques

Question 21

The physician is concerned that a pregnant patient may be at risk for delivering prematurely. What would be the best biochemical marker to measure to assess the situation?

A. Inhibin A
B. a1-Fetoprotein
C. Fetal fibronectin
D. Human chorionic gonadotropin

Answer 21

C. Fetal fibronectin

Fibronectin is an adhesive glycoprotein that
functions with collagen to support cell adhesion.
It is a normal constituent in the placenta and
amniotic fluid. As labor begins, a change occurs
in cell adhesion that affects the placenta and
uterine wall. The level of fetal fibronectin
increases in the secretions of the cervix and
vagina. When this occurs prematurely, the
increase in fetal fibronectin is used to predict
risk of premature birth. Inhibin A, a1-fetoprotein, human chorionic gonadotropin, and unconjugated estriol are used together in the quadruple test to assess risk for such disorders as Down
syndrome

Question 22

Bence Jones proteinuria is a condition characterized by the urinary excretion of what type of light chain?

A. Kappa light chains
B. Lambda light chains
C. Both kappa and lambda light chains
D. Either kappa or lambda light chains

Answer 22

D. Either kappa or lambda light chains

The immunoglobulins are composed of both heavy and light chains. In Bence Jones proteinuria, there is an overproduction of one type of light chain by a single clone of plasma cells. Therefore, the plasma cells produce either an excessive amount of kappa light chains or an excessive amount of lambda light chains. The light-chain
type produced is in such abundance that the renal threshold is exceeded, resulting in the excretion of free light chains of the kappa or lambda type in the urine. The type of light chain excreted in the urine
may be identified by performing immunoelectrophoresis on a concentrated urine specimen. In addition, immunoturbidimetric and immunonephelometric methods may also be used.

Question 23

Which of the following is not characteristic of multiple myeloma?

A. Monoclonal band in the gamma region
B. Hypercalcemia
C. Hyperalbuminemia
D. Hyperglobulinemia

Answer 23

C. Hyperalbuminemia

In multiple myeloma there is an abnormal
proliferation of plasma cells. These plasma cells
produce a homogeneous immunoglobulin protein
that stains as a well-defined peak in the gamma
region. Because of the presence of this monoclonal protein, the serum total protein will be elevated. Bone destruction is commonly seen in this disorder, with the plasma cells forming densely
packed groups in the lytic areas. Hypercalcemia
is primarily the result of bone destruction

Question 24

What technique is used to quantify specific immunoglobulin classes?

A. Immunonephelometry
B. Serum protein electrophoresis
C. Isoelectric focusing
D. Immunoelectrophoresis

Answer 24

A. Immunonephelometry

Immunonephelometric and immunoturbidimetric techniques are used to quantify specific immunoglobulin classes. Nephelometric techniques used to quantify the immunoglobulins are based on the measurement of light scatter by the antigen-antibody complexes formed. This method also calls for the comparison of
unknowns with standards. Although radial immunodiffusion can be used to quantify the immunoglobulins, it is not a method of choice.
Serum protein electrophoresis, immunoelectrophoresis, and isoelectric focusing cannot be used to quantify the immunoglobulins

Question 25

Portal cirrhosis is a chronic disease of the liver. As observed on an electrophoretic serum protein pattern, what is a predominant characteristic of this disease?

A. Monoclonal band in the gamma-globulin region
B. Polyclonal band in the gamma-globulin region
C. Bridging effect between the beta- and gamma-globulin bands
D. Increase in the alpha2-globulin band

Answer 25

C. Bridging effect between the beta- and gamma-globulin bands

Portal cirrhosis is a chronic disease of the
liver in which fibrosis occurs as a result of tissue
necrosis and diffuse small nodules form as liver
cells regenerate, with a concomitant distortion
of liver structure. The cause of this disorder may
include alcoholism, malnutrition, or submassive
hepatic necrosis. When a serum protein electrophoresis is performed, the characteristic pattern seen in portal cirrhosis is an elevation of both the gamma- and beta-globulin regions, with
these two regions showing a bridging or fusing appearance. This beta-gamma bridging effect is due to an increased level of IgA, which migrates with beta mobility. It should also be noted that
the albumin level is depressed

Question 26

The abnormal metabolism of several of the amino acids has been linked with disorders classified as inborn errors of metabolism. What technique is used to differentiate among several different amino acids?

A. Electrophoresis
B. Microbiological analysis
C. Enzyme immunoassay
D. Chromatography

Answer 26

D. Chromatography

Although microbiological analysis and chemical analysis may be employed to detect and quantify a specific amino acid, chromatographic analysis is preferred as a screening technique for amino acid abnormalities or when differentiation among several amino acids is necessary. Thin-layer chromatography, either
one- or two-dimensional, is being used in conjunction with a mixture of ninhydrin-collidine for color development. To quantify amino acids
high-performance liquid chromatography, ionexchange chromatography, and tandem mass spectrometry are used.

Question 27

Serum protein electrophoresis is routinely performed on the serum obtained from a clotted blood specimen. If a plasma specimen is substituted for serum, how will the electrophoresis be affected?

A. Electrophoresis cannot be performed
because the anticoagulant will retard the mobilities of the protein fractions.
B. Electrophoresis cannot be performed because the anticoagulant will cause migration of the protein fractions in the direction of the cathode.
C. Electrophoresis will show an extra fraction in the beta-gamma region.
D. Electrophoresis will show an extra fraction in the prealbumin area.

Answer 27

C. Electrophoresis will show an extra fraction in the beta-gamma region.

Protein electrophoresis is performed on a
serum specimen. If plasma is substituted for
serum, the electrophoresis will show an extra
fraction in the beta-gamma region, because fibrinogen is a beta2-globulin. This extra fraction represents the protein fibrinogen that is present in a plasma specimen. Fibrinogen contributes
approximately 0.2-0.4 g/dL to the total protein
concentration.

Question 28

In serum protein electrophoresis, when a barbital buffer of pH 8.6 is employed, what protein fraction will migrate the fastest toward the anode?

A. Albumin
B. Alpha!-globulin
C. Beta-globulin
D. Gamma-globulin

Answer 28

A. Albumin

When serum proteins are exposed to a buffer
solution of pH 8.6, the proteins take on a net
negative charge. The negatively charged proteins
will migrate toward the anode (+) when exposed
to an electrical field. Albumin migrates the
fastest toward the anode whereas the gammaglobulins remain close to the point of application and actually move slightly in a cathodic (-)
direction because of the effects of endosmosis.
The order of migration of the serum proteins,
starting at the anode with the fastest-moving
fraction, is albumin, alpha)-globulin, alpha2-
globulin, beta-globulin, and gamma-globulin

Question 29

In which of the following disorders would the maternal serum level of a1-fetoprotein not be elevated?

A. Neural tube defect
B. Spinabifida
C. Fetal distress
D. Down syndrome

Answer 29

D. Down syndrome

a1-Fetoprotein, synthesized by the fetus,
peaks at 13 weeks and declines at 34 weeks of
gestation. When concern exists for the wellbeing of the fetus, maternal serum AFP is measured between 15 and 20 weeks of gestation. An increased AFP level in maternal serum is associated with such disorders as neural tube defects, spina bifida, and fetal distress. A decreased AFP level in maternal serum is characteristic of
Down syndrome.

Question 30

A male patient, 48 years old, mentions during his annual physical that he has been having difficulty urinating. The physician performs a rectal examination, and he orders a total prostate-specific antigen (PSA) and free PSA. The patient has the tests done the following week, and the total PSA result is 3.1 ng/mL and the free PSA is 0.3 ng/mL. What do these
results suggest?

A. Both are normal, no disease present
B. Benign prostatic hypertrophy
C. Increased risk of prostate cancer
D. Free PSA is low and does not correlate
with total PSA

Answer 30

C. Increased risk of prostate cancer

The normal range for total PSA is sometimes
referenced as less than 4.0 ng/mL. Early detection guidelines endorse a lower cutoff for total PSA up to 2.5 ng/mL and recommend that values >2.5 ng/mL should be followed up by performing a biopsy. Men with prostate cancer tend to have lower % free PSA (free PSA/total PSA) than men with benign disease; thus lower % free PSA is associated with a higher risk of prostate cancer. In the case presented, the patient’s total PSA was 3.1 ng/mL with a free PSA of 0.3
ng/mL, which is 10% free PSA. This low percentage is suggestive of a higher probability of cancer, whereas a percentage >25% is associated with lower risk of cancer.

Question 31

Which of the following is not associated with carcinoembryonic antigen?

A. Increased levels seen with malignancies of the lungs
B. Quantified by using capillary electrophoresis
C. Used to monitor treatment of colon cancer
D. Glycoprotein in nature

Answer 31

B. Quantified by using capillary electrophoresis

Carcinoembryonic antigen (CEA), a glycoprotein, is found in increased amounts in serum when malignant tumors of the colon, lung,
pancreas, stomach, and breast are present. Care must be exercised in treating CEA as a diagnostic test, because elevated values are also seen in smokers, hepatitis patients, and patients with
several other nonmalignant disorders. Clinically, CEA is more valuable in prognosis and treatment monitoring. Enzyme immunoassay and
other types of immunoassays are available for the quantification of CEA

Question 32

In cases of hepatoma, which protein not normally found in adult serum is synthesized by liver cells?

A. A1-Acid glycoprotein
B. A1-Fetoprotein
C. a2-Macroglobulin
D. Carcinoembryonic antigen

Answer 32

B. A1-Fetoprotein

AFP is normally produced only by the fetus,
with blood levels disappearing shortly after
birth. However, in the adult, such conditions as
hepatoma or teratoma stimulate the production
of this primitive protein by the tumor cells. The
quantification of AFP may be used both diagnostically and as a monitor of chemotherapy.

Question 33

Which of the following is false about PSA?

A. Serum quantified using immunoassays
B. Single-chain glycoprotein
C. Used as a tumor marker
D. Not elevated in benign prostatic hyperplasia

Answer 33

D. Not elevated in benign prostatic hyperplasia

PSA is a single-chain glycoprotein whose function aids in the liquefaction of seminal coagulum. PSA is found specifically in the
prostate gland, and elevated levels are associated with prostate cancer and benign prostatic hyperplasia (BPH). Thus, combining the quantification of PSA with the performance of the digital rectal examination is more beneficial for prostate cancer detection. Immunoassays using enzyme, fluorescent, and chemiluminescent labels are available to quantify PSA

Question 34

Which of the following is an oncofetal antigen that is elevated in nonmucinous epithelial ovarian cancer?

A. CA 549
B. CA 125
C. CA 19-9
D. CA 15-3

Answer 34

B. CA 125

CA 125 is an oncofetal antigen, glycoprotein
in nature, that is produced by ovarian epithelial
cells. The majority of individuals with nonmucinous epithelial ovarian cancer exhibit elevated levels of CA 125. CA 125 is also increased in
other malignancies, including endometrial, breast, colon, pancreas, and lung cancers. Several benign disorders also exhibit CA 125 elevated levels. It appears that the primary usefulness of CA 125 is in monitoring the success of therapy in treating ovarian carcinoma.

Question 35

Which of the following is a sialylated Lewis blood group antigen associated with colorectal carcinoma?

A. CA 19-9
B. CA 15-3
C. CA549
D. CEA

Answer 35

A. CA 19-9

CA 19-9 is an oncofetal protein that is a sialylated Lewis blood group antigen. It is found in increased levels in colorectal carcinoma as well as in gastric, hepatobiliary, and pancreatic cancers. CA 19-9 is also elevated in several benign disorders, including pancreatitis, extra-hepatic cholestasis, and cirrhosis. The combination use of
CA 19-9 and CEA (carcinoembryonic antigen) is helpful in monitoring the recurrence of colorectal cancer

Question 36

Which of the following disorders is not
associated with an elevation of serum
a1-fetoprotein?

A. Testicular germ cell tumors
B. Prostatic carcinoma
C. Pancreatic carcinoma
D. Gastric carcinoma

Answer 36

B. Prostatic carcinoma

Elevations of serum levels of AFP are found
in a number of malignant as well as benign disorders. Although AFP is considered the most specific laboratory test for hepatocellular carcinoma, increased levels are also found in benign liver disease, including viral hepatitis, chronic active hepatitis, and cirrhosis. Other malignant disorders associated with increased levels of
AFP include testicular and ovarian germ cell tumors, pancreatic carcinoma, gastric carcinoma, and colonic carcinoma. Thus, AFP is not
a tissue-specific tumor marker. AFP is not elevated in prostatic cancer, which is characterized by an elevation in PSA. The use of AFP in conjunction with human chorionic gonadotropin (hCG) is effective in monitoring treatment and identifying recurrence of testicular cancer.

Question 37

Which of the following is not associated
with human chorionic gonadotropin?

A. B subunit confers immunogenic
specificity
B. Used to confirm pregnancy
C. Used as a tumor marker
D. Found in hepatoma

Answer 37

D. Found in hepatoma

hCG is a dimer consisting of alpha and beta polypeptide chains, with the (3 subunit conferring immunogenic specificity. Although hCG is
more commonly associated with testing to confirm pregnancy, it is also associated with certain forms of cancer. (3-hCG is used as a tumor marker for hydatidiform mole, gestational choriocarcinoma, and placental-site trophoblastic tumor. hCG’s utility also extends to monitoring the success of therapy in testicular and ovarian
germ cell tumors. In addition, increased levels of hCG have been identified in hematopoietic malignancy, melanoma, gastrointestinal tract neoplasms, sarcoma, and lung, breast, and renal cancers.

Question 38

Although serum elevations are not generally seen in early stages, which of the following tumor markers are elevated in more advanced stages of breast cancer?

A. CEA and AFP
B. AFP and C A 125
C. PSA and CA 15-3
D. CA 15-3 and CA 549

Answer 38

D. CA 15-3 and CA 549

CA 15-3 and CA 549 are oncofetal antigens that are glycoprotein in nature. CA 15-3 is found on mammary epithelium. Increased serum levels of CA 15-3 are found in breast, pancreatic, lung,
colorectal, and liver cancers. CA 549 is found in the cell membrane and luminal surface of breast tissue. Increased serum levels of CA 549 are found in breast, lung, prostate, and colon cancers. Although both CA 15-3 and CA 549 are elevated in more advanced stages of breast
cancer, neither is helpful in detecting early stages of breast cancer