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Question 1

Which of the following apoproteins is inversely related to risk for coronary heart disease and is a surrogate marker for HDL?

A. Apo-A1
B. Apo-B
C. Apo-B100
D. Apo-E

Answer 1

A. Apo-A1

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Apo-A1 is the predominant apoprotein associated with the high-density lipoprotein (HDL) molecule, activates (lecithin cholesterol acyltransferase [LCAT]), and is associated with reverse cholesterol transport. As a result, it is protective against coronary artery disease.

Question 2

A patient sample is assayed for fasting triglycerides and a triglyceride value of 1036 mg/dL. This value is of immediate concern because of its association with which of the following conditions?

A. Coronary heart disease
B. Diabetes
C. Pancreatitis
D. Gout

Answer 2

C. Pancreatitis

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Marked increases in triglyceride levels, between 1000 and 2000 mg/dL have been associated with increased risk for the development of pancreatitis.

Question 3

Patients with Waldenström’s macroglobulinemia exhibit abnormally large amounts of:

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

Answer 3

A. IgM

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Waldenström’s primary macroglobulinemia (WM), or simply macroglobulinemia, is a B cell disorder characterized by the infiltration of lymphoplasmacytic cells into bone marrow and the presence of an IgM monoclonal gammopathy.

Question 4

Which test is the most sensitive in detecting early monoclonal gammopathies?

A. High-resolution serum protein electrophoresis
B. Urinary electrophoresis for monoclonal light chains
C. Capillary electrophoresis of serum and urine
D. Serum-free light chain immunoassay

Answer 4

D. Serum-free light chain immunoassay

Feedback

Measurement of free light chains is recommended along with protein electrophoresis when testing for myeloma.

Free light chains are normally present in serum because L chains are made at a faster rate than H chains.

Question 5

Which test is the most useful way to evaluate the response to treatment for multiple myeloma?

A. Measure of total immunoglobulin
B. Measurement of 24-hour urinary light chain concentration (Bence-Jones protein)
C. Capillary electrophoresis of M-protein recurrence
D. Measurement of serum-free light chains

Answer 5

D. Measurement of serum-free light chains

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Unlike electrophoresis methods, serum free light chain assays are quantitative and an increase in free light chain production with an abnormal kappa:lambda ratio occurs earliest in recurrence of myeloma.

Question 6

Which of the following is the most common application of IMMUNOELECTROPHORESIS (IEP)?

A. Identification of the absence of a normal serum protein

B. Structural abnormalities of proteins
C. Screening for circulating immune complexes
D. Diagnosis of monoclonal gammopathies

Answer 6

D. Diagnosis of monoclonal gammopathies

Question 7

PRE-ECLAMPSIA, also referred to as TOXEMIA OF PREGNANCY is marked by specific symptoms including:

A. Water retention (with swelling particularly in the feet, legs, and hands)
B. High blood pressure
C. Protein in the urine
D. All of these

Answer 7

D. All of these

Question 8

A sensitive, although not specific indicator of damage to the kidneys:

A. Urea
B. Creatinine
C. Proteinuria
D. Cystatin C

Answer 8

C. Proteinuria

Question 9

At pH 8.6, proteins are _________ charged and migrate toward the _________.

A. Negatively, anode
B. Positively, cathode
C. Positively, anode
D. Negatively, cathode

Answer 9

A. Negatively, anode

Question 10

For albumin assay, absorbance at 630 nm is less likely to be affected by bilirubin or hemoglobin in the sample. Which dye gives a much greater absorbance change at 630 nm than it would at 500 nm?

A. HABA (Hydroxyazobenzene-benzoic acid)
B. BCG (Bromcresol green)

Answer 10

B. BCG (Bromcresol green)

Question 11

Which of the following dyes is the MOST SPECIFIC for measurement of albumin?

A. Bromcresol green (BCG)
B. Bromcresol purple (BCP)
C. Tetrabromosulfophthalein
D. Tetrabromphenol blue

Answer 11

B. Bromcresol purple (BCP)

Feedback
BCP is more specific for albumin than BCG.

Question 12

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

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

Answer 12

C. Dehydration

Question 13

ARTIFACTUAL INCREASE in albumin concentration:

A. Prolonged tourniquet application
B. Dehydration
C. Nephrotic syndrome
D. Inflammation

Answer 13

A. Prolonged tourniquet application

Question 14

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 14

A. Microalbuminuria

Question 15

Most abundant amino acid in the body:

A. Glutamine
B. Lysine
C. Phenylalanine
D. Tyrosine

Answer 15

A. Glutamine

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Glutamine is the most abundant amino acid in the body, being involved in more metabolic processes than any other amino acid.

Question 16

Precursor of the adrenal hormones epinephrine, norepinephrine, and dopamine and the thyroid hormones, including thyroxine:

A. Glutamine
B. Lysine
C. Phenylalanine
D. Tyrosine

Answer 16

D. Tyrosine

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Tyrosine is a precursor of the adrenal hormones epinephrine, norepinephrine, and dopamine and the thyroid hormones, including thyroxine.

It is important in overall metabolism, aiding in the functions of the adrenal, thyroid, and pituitary glands.

Question 17

The plasma protein mainly responsible for maintaining colloidal osmotic pressure in vivo is:

A. Albumin
B. Hemoglobin
C. Fibrinogen
D. Alpha2-macroglobulin

Answer 17

A. Albumin

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Albumin is responsible for nearly 80% of the colloid osmotic pressure (COP) of the intravascular fluid, which maintains the appropriate fluid balance in the tissue.

Question 18

Sensitive marker of poor nutritional status:

A. Prealbumin
B. Fibrinogen
C. Gc-globulin
D. Orosomucoid

Answer 18

A. Prealbumin

Feedback

A low prealbumin level is a sensitive marker of poor nutritional status.

When a diet is deficient in protein, hepatic synthesis of proteins is reduced, with the resulting decrease in the level of the proteins originating in the liver, including prealbumin, albumin, and β-globulins. Because prealbumin has a short half-life of approximately 2 days, it decreases more rapidly than do other proteins.

Question 19

Nutritional assessment with poor protein-caloric status is associated with:

A. A decreased level of prealbumin
B. A low level of γ-globulins
C. An elevated ceruloplasmin concentration
D. An increased level of α1-fetoprotein

Answer 19

A. A decreased level of prealbumin

Question 20

Retinol (vitamin A) binding protein

A. Albumin
B. Alpha1-antitrypsin
C. Fibronectin
D. Prealbumin

Answer 20

D. Prealbumin

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Prealbumin is the transport protein for thyroxine and triiodothyronine (thyroid hormones); it also binds with retinol-binding protein to form a complex that transports retinol (vitamin A) and is rich in tryptophan.

Question 21

Which of the following conditions is the result of a LOW ALPHA1-ANTITRYPSIN LEVEL?

A. Asthma
B. Emphysema
C. Pulmonary hypertension
D. Sarcoidosis

Answer 21

B. Emphysema

Question 22

All are conditions associated with an elevated AFP, EXCEPT:

A. Neural tube defects
B. Spina bifida
C. Anencephaly
D. Down syndrome

Answer 22

D. Down syndrome

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Conditions associated with an elevated AFP level include spina bifida, neural tube defects, abdominal wall defects, anencephaly (absence of the major portion of the brain), and general fetal distress.

Low levels of maternal AFP indicate an increased risk for Down syndrome and trisomy 18, while it is increased in the presence of twins and neural tube defects.

Question 23

In nephrotic syndrome, the levels of serum ______ may increase as much as 10 times because its large size aids in its retention.

A. Alpha2-macroglobulin
B. Ceruloplasmin
C. Orosomucoid
D. Transferrin

Answer 23

A. Alpha2-macroglobulin

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In nephrosis, the levels of serum α2-macroglobulin may increase as much as 10 times because its large size aids in its retention. The protein is also increased in diabetes and liver disease.

Use of contraceptive medications and pregnancy increase the serum levels by 20%.

Question 24

Orosomucoid:

A. Alpha1-antitrypsin
B. Alpha1-chymotrypsin
C. Alpha1-fetoprotein
D. Alpha1-acid glycoprotein

Answer 24

D. Alpha1-acid glycoprotein

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α1-Acid Glycoprotein (Orosomucoid)
α1-Acid glycoprotein (AAG), a major plasma glycoprotein, is negatively charged even in acid solutions, a fact that gave it its name. This protein is produced by the liver and is an acute-phase reactant.

Question 25

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

A. Alpha2-macroglobulin
B. Beta2-microglobulin
C. C-reactive protein
D. Ceruloplasmin

Answer 25

B. Beta2-microglobulin

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β2-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 β2-microglobulin are associated with renal failure, lymphocytosis, rheumatoid arthritis, and systemic lupus erythematosus.

Question 26

A glycoprotein used to help predict the short-term risk of PREMATURE DELIVERY:

A. Adiponectin
B. Alpha-fetoprotein
C. Amyloid
D. Fetal fibronectin

Answer 26

D. Fetal fibronectin

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Fetal fibronectin (fFN) is a glycoprotein used to help predict the short-term risk of premature delivery.

Question 26

Variants demonstrate a wide variety of cellular interactions, including roles in cell adhesion, tissue differentiation, growth, and wound healing:

A. Beta-trace protein
B. Cystatin C
C. Fibronectin
D. Troponin

Answer 26

C. Fibronectin

Question 27

BIOCHEMICAL MARKER OF BONE RESORPTION that can be detected in serum and urine:

A. Beta-trace protein
B. Crosslinked C-telopeptides (CTX)
C. Fibronectin
D. Troponin

Answer 27

B. Crosslinked C-telopeptides (CTX)

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Cross-linked C-telopeptides (CTXs) are proteolytic fragments of collagen I formed during bone resorption (turnover).

CTX is a biochemical marker of bone resorption that can be detected in serum and urine.

Question 28

An accurate marker of CSF leakage:

A. Beta-trace protein
B. Crosslinked C-telopeptides (CTX)
C. Fibronectin
D. Troponin

Answer 28

A. Beta-trace protein

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β-Trace protein (BTP; synonym prostaglandin D synthase) is a 168–amino acid, low-molecular-mass protein in the lipocalin protein family. Recently, it was verified that BTP was established as an accurate marker of CSF leakage.

It has also been reported recently as a potential marker in detecting impaired renal function, although no more sensitive than cystatin C.

Question 29

Recently proposed new marker for the early assessment of changes to the glomerular filtration rate:

A. Adiponectin
B. Beta-trace protein
C. Cross-linked C-telopeptides (CTX)
D. Cystatin C

Answer 29

D. Cystatin C

Question 30

Supplemental tests to help differentiate a diagnosis of ALZHEIMER DISEASE from other forms of dementia:

A. Amyloid β42 (Aβ42) and Tau protein
B. Crosslinked C-telopeptides (CTX)
C. Fibronectin
D. Troponin

Answer 30

A. Amyloid β42 (Aβ42) and Tau protein

Feedback

In a symptomatic patient, low Aβ42 along with high Tau reflects an increased likelihood of Alzheimer disease, but it does not mean that the person definitely has Alzheimer disease. If a patient does not have abnormal levels of these proteins, then the dementia is more likely due to a cause other than Alzheimer disease.

Question 31

As a cardiac biomarker, this protein has been used in conjunction with troponin to help diagnose or rule out a heart attack:

A. Brain natriuretic peptide (BNP)
B. Cross-linked C-telopeptides (CTX)
C. Cystatin C
D. Myoglobin

Answer 31

D. Myoglobin

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As a cardiac biomarker, myoglobin has been used in conjunction with troponin to help diagnose or rule out a heart attack. When striated muscle is damaged, myoglobin is released, elevating the blood levels.

In an AMI, this increase is seen within 2 to 3 hours of onset and reaches peak concentration in 8 to 12 hours. Myoglobin is a small molecule freely filtered by the kidneys, allowing levels to return to normal in 18 to 30 hours after the AMI.

Because of the speed of appearance and clearance of myoglobin, it is also a useful marker for monitoring the success or failure of reperfusion.

Question 32

“Gold standard” in the diagnosis of acute coronary syndrome (ACS):

A. Brain natriuretic peptide (BNP)
B. Cross-linked c-telopeptides
C. Myoglobin
D. Troponin

Answer 32

D. Troponin

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ACUTE CORONARY SYNDROME/MYOCARDIAL INFARCTION

Cardiac troponin (cTn) represents a complex of regulatory proteins that include troponin I (cTnI) and troponin T (cTnT) that are specific to heart muscle.

cTnI and cTnT are the “gold standard” in the diagnosis of acute coronary syndrome (ACS). cTn should be measured in all patients presenting with symptoms suggestive of ACS, in conjunction with physical examination and ECG.

Question 33

Which test, if elevated, would PROVIDE INFORMATION about risk for developing coronary artery disease?

A. CK-MB
B. hs-CRP
C. Myoglobin
D. Troponin

Answer 33

B. hs-CRP

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HIGH-SENSITIVITY CRP
Considered a GOOD PREDICTOR TEST for assessing cardiovascular risk

CK-MB, TROPONIN AND MYOGLOBIN
Used to assess if a myocardial infarction HAS OCCURRED

Question 34

If elevated, which laboratory test would support a diagnosis of CONGESTIVE HEART FAILURE?

A. Albumin cobalt binding
B. B-type natriuretic peptide
C. Homocysteine
D. Troponin

Answer 34

B. B-type natriuretic peptide

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B-type (brain) natriuretic peptide (BNP) is used to determine if physical symptoms are related to congestive heart failure.

Question 35

Which two tests detect swelling of the ventricles that occurs in congestive heart failure?

A. BNP and electrocardiogram
B. BNP and echocardiogram
C. Troponin T and electrocardiogram
D. Troponin I and echocardiogram

Answer 35

B. BNP and echocardiogram

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DIAGNOSIS OF CONGESTIVE HEART FAILURE:
Until recently, this condition was diagnosed strictly on the basis of symptomatology and/or as a result of procedures such as echocardiography, but more recently a biomarker for this condition is the brain form or B-type natriuretic peptide (BNP), which has been approved as a definitive test for this condition and appears to be an excellent marker for early heart failure.

Question 36

Which of the following laboratory tests is a marker for ISCHEMIC HEART DISEASE?

A. Albumin cobalt binding
B. CK-MB isoforms
C. Free fatty acid binding protein
D. Myosin light chain

Answer 36

A. Albumin cobalt binding

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Albumin cobalt binding is a test that measures ischemia-modified albumin, which is a marker for ischemic heart disease.

Question 37

The turbid, or milky, appearance of serum after fat ingestion is termed postprandial lipemia, which is caused by the presence of what substance?

A. Bilirubin
B. Cholesterol
C. Chylomicron
D. Phospholipid

Answer 37

C. Chylomicron

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These chylomicrons enter the blood through the lymphatic system, where they impart a turbid appearance to serum.

Question 38

When the plasma appears OPAQUE AND MILKY, the triglyceride level is probably:

A. Less than 100 mg/dL
B. Less than 200 mg/dL
C. Greater than 300 mg/dL
D. Greater than 600 mg/dL

Answer 38

D. Greater than 600 mg/dL

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The appearance of the plasma or serum can be observed and noted after a minimum 12-hour fast.

If the plasma is clear, the triglyceride level is probably less than 200 mg/dL. When the plasma appears hazy or turbid, the triglyceride level has increased to greater than 300 mg/dL, and if the specimen appears
opaque and milky (lipemic, from chylomicrons), the triglyceride level is probably greater than 600 mg/dL.

Note:
1. Clear plasma: TAG < 200 mg/dL
2. Hazy or turbid plasma: TAG > 300 mg/dL
3. Opaque or milky plasma: TAG > 600 mg/dL

Question 39

Which of the following tests would most likely be included in a routine lipid profile?

A. Total cholesterol, triglyceride, fatty acid, chylomicron
B. Total cholesterol, triglyceride, HDL cholesterol, phospholipid
C. Triglyceride, HDL cholesterol, LDL cholesterol, chylomicron
D. Total cholesterol, triglyceride, HDL cholesterol, LDL cholesterol

Answer 39

D. Total cholesterol, triglyceride, HDL cholesterol, LDL cholesterol

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A “routine” lipid profile would most likely consist of the measurement of total cholesterol, triglyceride, HDL cholesterol, and LDL cholesterol.

Question 40

To produce reliable results, when should blood specimens for lipid studies be drawn?

A. Immediately after eating
B. Anytime during the day
C. In the fasting state, approximately 2 to 4 hours after eating
D. In the fasting state, approximately 12 hours after eating

Answer 40

D. In the fasting state, approximately 12 hours after eating

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Blood specimens for lipid studies should be drawn in the fasting state at least 9 to 12 hours after eating. Although fat ingestion only slightly affects cholesterol levels, the triglyceride results are greatly affected. Triglycerides peak at about 4 to 6 hours after a meal, and these exogenous lipids should be cleared from the plasma before analysis.

Question 41

Which of the following lipid tests is LEAST affected by the fasting status of the patient?

A. Cholesterol
B. Triglyceride
C. Fatty acid
D. Lipoprotein

Answer 41

A. Cholesterol

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Total cholesterol screenings are commonly performed on nonfasting individuals.

Total cholesterol is only slightly affected by the fasting status of the individual, whereas triglycerides, fatty acids, and lipoproteins are greatly affected.

Question 42

The kinetic methods for quantifying serum triglyceride employ enzymatic hydrolysis. The hydrolysis of triglyceride may be accomplished by what enzyme?

A. Amylase
B. Leucine aminopeptidase
C. Lactate dehydrogenase
D. Lipase

Answer 42

D. Lipase

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It is first necessary to hydrolyze the triglycerides to free fatty acids
and glycerol. This hydrolysis step is catalyzed by the enzyme lipase.

The glycerol is then free to react in the enzyme-coupled reaction system that includes glycerokinase, pyruvate kinase, and lactate dehydrogenase or in the enzyme-coupled system that includes glycerokinase, glycerophosphate oxidase, and peroxidase.

Question 43

The largest and the least dense of the lipoprotein particles:

A. LDL
B. HDL
C. VLDL
D. Chylomicrons

Answer 43

D. Chylomicrons

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Chylomicrons, which contain apo B-48, are the largest and the least dense of the lipoprotein particles.

HDL, the smallest and most dense lipoprotein particle, is synthesized by both the liver and the intestine.

Question 44

The smallest and most dense lipoprotein particle:

A. LDL
B. HDL
C. VLDL
D. Chylomicrons

Answer 44

B. HDL

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Chylomicrons, which contain apo B-48, are the largest and the least dense of the lipoprotein particles.

HDL, the smallest and most dense lipoprotein particle, is synthesized by both the liver and the intestine.

Question 45

An abnormal lipoprotein present in patients with biliary cirrhosis or cholestasis:

A. LDL
B. B-VLDL
C. Lp(a)
D. LpX

Answer 45

D. LpX

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Lipoprotein X is an abnormal lipoprotein present in patients with biliary cirrhosis or cholestasis and in patients with mutations in lecithin:cholesterol acyltransferase (LCAT), the enzyme that esterifies cholesterol.

Question 46

Exogenous triglycerides are transported in the plasma in what form?

A. Phospholipids
B. Cholestryl esters
C. Chylomicrons
D. Free fatty acids

Answer 46

C. Chylomicrons

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From the epithelial cells, the chylomicrons are released into the lymphatic system, which transports chylomicrons to the blood. The chylomicrons may then carry the triglycerides to adipose tissue for storage, to organs for catabolism, or to the liver for incorporation of the triglycerides into very-low-density lipoproteins (VLDLs). Chylomicrons are normally cleared from plasma within 6 hours after a meal.

Question 47

Select the lipoprotein fraction that carries most of the endogenous triglycerides.

A. VLDL
B. HDL
C. LDL
D. Chylomicrons

Answer 47

A. VLDL

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VLDL transports the majority of endogenous triglycerides, while the triglycerides of chylomicrons are derived entirely from dietary absorption.

Question 48

Each lipoprotein fraction is composed of varying amounts of lipid and protein components. The beta-lipoprotein fraction consists primarily of which lipid?

A. Fatty acid
B. Cholesterol
C. Phospholipid
D. Triglyceride

Answer 48

B. Cholesterol

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The beta-lipoprotein fraction is composed of approximately 50% cholesterol, 6% triglycerides, 22% phospholipids, and 22% protein.

The beta-lipoproteins, which are also known as the low-density lipoproteins (LDLs), are the principal transport vehicle for cholesterol
in the plasma.

Question 49

The protein composition of HDL is what percentage by weight?

A. Less than 2%
B. 25%
C. 50%
D. 90%

Answer 49

C. 50%

Feedback

About 50% of the weight of HDL is protein, largely apo A-I and apo A-II. The HDL is about 30% phospholipid and 20% cholesterol by weight.

Question 50

High levels of cholesterol leading to increased risk of coronary artery disease would be associated with which lipoprotein fraction?

A. LDL
B. VLDL
C. HDL
D. Chylomicrons

Answer 50

A. LDL

Question 51

What is the sedimentation nomenclature associated with alpha-lipoprotein?

A. Very-low-density lipoproteins (VLDLs)
B. High-density lipoproteins (HDLs)
C. Low-density lipoproteins (LDLs)
D. Chylomicrons

Answer 51

D. Chylomicrons

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The HDLs, also known as the alpha-lipoproteins, have the greatest density of 1.063-1.210 g/mL and move the fastest electrophoretically toward the anode.

Question 52

Coronary heart disease POSITIVE risk factor:

A. LDL-C concentration < 100 mg/dL
B. HDL-C concentration ≥ 60 mg/dL
C. HDL-C concentration < 40 mg/dL
D. None of these

Answer 52

C. HDL-C concentration < 40 mg/dL

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POSITIVE (INCREASED) RISK FACTORS
 Age: ≥ 45 y for men; ≥ 55 y or premature menopause for women
 Family history of premature CHD
 Current cigarette smoking
 Hypertension (blood pressure ≥ 140/90 mm Hg or taking antihypertensive medication)
 LDL-C concentration ≥ 160 mg/dL (≥ 4.1 mmol/L), with ≤ 1 risk factor
 LDL-C concentration ≥ 130 mg/dL (3.4 mmol/L), with ≥ 2 risk factors
 LDL-C concentration ≥ 100 mg/dL (2.6 mmol/L), with CH D or risk equivalent
 HDL-C concentration < 40 mg/dL (< 1.0 mmol/L)
 Diabetes mellitus = CH D risk equivalent
 Metabolic syndrome (multiple metabolic risk factors)

NEGATIVE (DECREASED) RISK FACTORS
 HDL-C concentration ≥ 60 mg/dL (≥ 1.6 mmol/L)
 LDL-C concentration < 100 mg/dL (< 2.6 mmol/L)

Question 52

The quantification of the high-density lipoprotein cholesterol level is thought to be significant in the risk assessment of what disease?

A. Pancreatitis
B. Cirrhosis
C. Coronary artery disease
D. Hyperlipidemia

Answer 52

C. Coronary artery disease

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The quantification of the HDL cholesterol level is thought to contribute in assessing the risk that an individual may develop coronary artery disease (CAD).

There appears to be an inverse relationship between HDL cholesterol and CAD. With low levels of HDL cholesterol, the risk of CAD increases.

Question 53

Which apoprotein is inversely related to risk of coronary heart disease?

A. Apoprotein A-I
B. Apoprotein B100
C. Apoprotein C-II
D. Apoprotein E4

Answer 53

A. Apoprotein A-I

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Apoprotein A-I and apo A-II are the principal apoproteins of HDL, and low apo A-I has a high correlation with atherosclerosis. Conversely, apo-B100 is the principal apoprotein of LDL, and an elevated level is a major risk factor in developing coronary heart disease.

Question 54

LDL primarily contains:

A. Apo AI
B. Apo-AII
C. Apo-B100
D. Apo-B48

Answer 54

C. Apo-B100

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LDL primarily contains apo B-100 and is more cholesterol rich than other apo B–containing lipoproteins.

Note:
Apo-AI, Apo-AII = HDL
Apo-B100 = LDL, VLDL
Apo-B48 = chylomicrons

Question 55

The VLDL fraction primarily transports what substance?

A. Cholesterol
B. Chylomicron
C. Triglyceride
D. Phospholipid

Answer 55

C. Triglyceride

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The VLDL fraction is primarily composed of triglycerides and lesser amounts of cholesterol and phospholipids.

Question 56

A commonly used precipitating reagent to separate HDL cholesterol from other lipoprotein cholesterol fractions:

A. Zinc sulfate
B. Trichloroacetic acid
C. Heparin-manganese
D. Isopropanol

Answer 56

C. Heparin-manganese

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Either a dextran sulfate-magnesium chloride mixture or a heparin sulfate-manganese chloride mixture may be used to precipitate the LDL and VLDL cholesterol fractions. This allows the HDL cholesterol fraction to remain in the supernatant.

Question 57

Which of the following is associated with Tangier disease?

A. Apoprotein C-II deficiency
B. Homozygous apo-B100 deficiency
C. Apoprotein C-II activated lipase
D. Apoprotein A-I deficiency

Answer 57

D. Apoprotein A-I deficiency

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Deficiency of apo A-I is seen in Tangier disease, a familial hypocholesterolemia.

Question 58

A patient’s total cholesterol is 300 mg/dL, his HDL cholesterol is 50 mg/dL, and his triglyceride is 200 mg/dL. What is this patient’s calculated LDL cholesterol?

A. 200
B. 210
C. 290
D. 350

Answer 58

B. 210

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Once the total cholesterol, triglyceride, and HDL cholesterol are known, LDL cholesterol can be quantified by using the Friedewald equation

LDL cholesterol = Total cholesterol — (HDL cholesterol + Triglyceride/5)

In this example, all results are in mg/dL:
LDL cholesterol
= 300 - (50 + 200/5)
= 300 - (90)
= 210 mg/dL

Question 59

The Friedewald formula is not valid for triglycerides over_____.

A. Triglycerides over 100 mg/dL
B. Triglycerides over 200 mg/dL
C. Triglycerides over 300 mg/dL
D. Triglycerides over 400 mg/dL

Answer 59

D. Triglycerides over 400 mg/dL

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LDL cholesterol may be calculated or measured directly:

1. Friedewald formula
   Indirect, not valid for triglycerides over 400mg/dL
   LDL cholesterol = total cholesterol — [HDL cholesterol + triglyceride/5]
2. Homogeneous assay uses detergents to block HDL and VLDL from reacting with the dye to form a colored chromogen product. An enzymatic cholesterol analysis is performed with only LDL cholesterol able to react.

Question 60

Select the order of mobility of lipoproteins electrophoresed on cellulose acetate or agarose at pH 8.6.

A. – Chylomicrons→pre-β →β→α+
B. – β→pre-β→α→chylomicrons +
C. – Chylomicrons →β→pre-β→α +
D. – α→β→pre-β→chylomicrons +

Answer 60

A. – Chylomicrons→pre-β →β→α+

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Although pre-β lipoprotein is lower in density than β lipoprotein, it migrates faster on agarose or cellulose acetate owing to its more negative apoprotein composition.

LIPOPROTEINS
1. By electrophoresis
From the origin: chylomicrons > beta (LDL) > prebeta (VLDL) > alpha (HDL) Anode
———
2. By ultracentrifugation
From the least dense and largest: chylomicrons > VLDL > LDL > HDL most dense and smallest

Question 61

Floating beta lipoprotein:

A. Lp(a)
B. B-VLDL

Answer 61

B. B-VLDL

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β-VLDL (‘floating β’ lipoprotein) is an abnormal lipoprotein that accumulates in type 3 hyperlipoproteinemia. It is richer in cholesterol than VLDL and apparently results from the defective catabolism of VLDL. The particle is found in the VLDL density range but migrates electrophoretically with or near LDL.

Question 62

Sinking pre-β-lipoprotein:

A. Lp(a)
B. B-VLDL

Answer 62

A. Lp(a)

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Lp(a) has a density similar to LDL, but migrates similarly to VLDL on electrophoresis. Thus it can be detected when the d > 1.006 g/mL protein is examined electrophoretically. When Lp(a) is present in concentrations exceeding 20-30 mg/dL (i.e., when it contributes more than about 10 mg/dL to the LDL-C measurement) an additional band with pre-β mobility is also observed in the d > 1.006 kg/L fraction (hence the name sinking pre-β-lipoprotein).

Question 63

Which of the following may be described as a variant form of LDL, associated with increased risk of atherosclerotic cardiovascular disease?

A. Lp(a)
B. HDL
C. Apo-AI
D. Apo-AII

Answer 63

A. Lp(a)

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Lipoprotein (a) is an apolipoprotein that is more commonly referred to as Lp(a). Although it is related structurally to LDL, Lp(a) is considered
to be a distinct lipoprotein class with an electrophoretic mobility in the prebeta region.

Lp(a) is believed to interfere with the lysis of clots by competing with plasminogen in the coagulation cascade, thus increasing the likelihood of atherosclerotic cardiovascular disease.

Question 64

Type V hyperlipoproteinemia:

A. Extremely elevated TG due to the presence of chylomicrons
B. Elevated LDL and VLDL
C. Elevated VLDL
D. Elevated VLDL and presence of chylomicrons

Answer 64

D. Elevated VLDL and presence of chylomicrons

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BLOOD LIPOPROTEIN PATTERNS IN PATIENTS WITH HYPERLIPOPROTEINEMIA
Type I: Extremely elevated TG due to the presence of chylomicrons
Type IIa: Elevated LDL
Type IIb: Elevated LDL and VLDL
Type III: Elevated cholesterol, TG; presence of B-VLDL
Type IV: Elevated VLDL
Type V: Elevated VLDL and presence of chylomicrons

Question 65

It is the result of POOR PERFUSION of the kidneys and therefore diminished glomerular filtration. The kidneys are otherwise normal in their functioning capabilities. Poor perfusion can result from dehydration, shock, diminished blood volume, or congestive heart failure.

A. Pre-renal azotemia
B. Renal azotemia
C. Post-renal azotemia

Answer 65

A. Pre-renal azotemia

Question 66

It is caused primarily by DIMINISHED GLOMERULAR FILTRATION as a consequence of acute or chronic renal disease. Such diseases include acute glomerulonephritis, chronic glomerulonephritis, polycystic kidney disease, and nephrosclerosis.

A. Pre-renal azotemia
B. Renal azotemia
C. Post-renal azotemia

Answer 66

B. Renal azotemia

Question 67

It is usually the result of any type of OBSTRUCTION in which urea is reabsorbed into the circulation. Obstruction can be caused by stones, an enlarged prostate gland, or tumors.

A. Pre-renal azotemia
B. Renal azotemia
C. Post-renal azotemia

Answer 67

C. Post-renal azotemia

Question 68

Urea is produced from:

A. The catabolism of proteins and amino acids
B. Oxidation of pyrimidines
C. The breakdown of complex carbohydrates
D. Oxidation of purines

Answer 68

A. The catabolism of proteins and amino acids

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Urea is generated by deamination of amino acids. Most is derived from the hepatic catabolism of proteins. Uric acid is produced by the catabolism of purines. Oxidation of pyrimidines produces orotic acid.

Question 69

Creatinine is formed from the

A. Oxidation of creatine
B. Oxidation of protein
C. Deamination of dibasic amino acids
D. Metabolism of purines

Answer 69

A. Oxidation of creatine

Question 70

The red complex developed in the Jaffe method todetermine creatinine measurements is a result of the complexing of creatinine with which of the following?

A. Alkaline picrate
B. Diacetyl monoxide
C. Sulfuric acid
D. Sodium hydroxide

Answer 70

A. Alkaline picrate

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The classic Jaffe reaction involves complexing of creatinine with an alkaline picrate solution to produce a red complex (Janovski complex).

Question 71

The most widely used test of overall renal function is:

A. Urea
B. Creatinine
C. Proteinuria
D. Cystatin C

Answer 71

B. Creatinine

Question 72

What substance may be measured as an alternative to creatinine for evaluating GFR?

A. Plasma urea
B. Cystatin C
C. Uric acid
D. Potassium

Answer 72

B. Cystatin C

Question 73

Uric acid is derived from the:

A. Oxidation of proteins
B. Catabolism of purines
C. Oxidation of pyrimidines
D. Reduction of catecholamines

Answer 73

B. Catabolism of purines

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Uric acid is the principal product of purine (adenosine and guanosine) metabolism.

Question 74

Which of the following is measured using glutamate dehydrogenase and is a measure of advanced stages, poor prognosis, and coma in liver disease?

A. Total bilirubin
B. Ammonia
C. Unconjugated bilirubin
D. Urea

Answer 74

B. Ammonia

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Severe liver disease is the most common cause of altered ammonia metabolism. Therefore the monitoring of ammonia levels may be used to determine prognosis.

Question 75

Blood ammonia levels are usually measured in order to evaluate:

A. Renal failure
B. Acid–base status
C. Hepatic coma
D. Gastrointestinal malabsorption

Answer 75

C. Hepatic coma

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Hepatic coma is caused by accumulation of ammonia in the brain as a result of liver failure. The ammonia increases central nervous system pH and is coupled to glutamate, a central nervous system neurotransmitter, forming glutamine. Blood and cerebrospinal fluid ammonia levels are used to distinguish encephalopathy caused by cirrhosis or other liver disease from nonhepatic causes and to monitor patients with hepatic coma.