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Examen OCQ Biochimie Clinique > Stage Biochimie > Flashcards

Stage Biochimie Flashcards

1
Q

Why should internal QC be performed?
a. To be sure that the QC material meets specifications
b. To examine if the control material is commutable (behaves like patient samples)
c. To have a high probability that correct patient results are released
d. To be able to pass the accreditation inspection
e. To examine if my measurement procedure gives results
similar to other laboratories

A

C

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2
Q

How should I interpret results when an EQA(External Quality assessement)/PT program uses noncommutable materials?
a. When my result is within the performance specifications, I can be confident that I have no bias compared with a true value.
b. When my result is different than the all method mean, I have to recalibrate my measurement procedure.
c. When my result is close to the target value for the peers in my measurement procedure group, I can be confident my laboratory is performing as well as my peers.
d. I should compare my results with results from other measurement procedures to be confident my laboratory is not biased.
e. I should compare my results with the average of all measurement procedure groups.

A

C

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3
Q

What is the advantage of using commutable QC materials?
a. They are similar to patient samples and should therefore not be used for QC.
b. They are suitable for internal QC but not for EQA and proficiency testing.
c. They should be avoided because they are contagious.
d. Their results provide information on the accuracy for patient samples if the target value is set by an RMP.
e. Their target values are always assigned by RMPs.

A

D

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4
Q

How can a reagent lot change affect a QC target value?
a. QC target values are not affected by reagent lot changes.
b. The QC target should be used to verify acceptability of a new reagent lot.
c. The non-commutability bias can be different, so the QC target value may need to be adjusted.
d. The non-commutability bias may be different, so the SD may need to be adjusted.
e. The reagent lot should be rejected if the QC target value is not recovered.

A

C

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5
Q

How is the SD estimated for an internal QC material?
a. From measurements made during the target value assignment of a QC material
b. From the long-term SD that includes most types of variability expected to influence the measurement procedure
c. From the instructions for use provided by the measurement procedure manufacturer
d. From reports of interlaboratory summaries
e. From the range of acceptable results provided by the QC material manufacturer

A

B

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6
Q

How frequently should QC samples be measured?
a. Based on the stability of a measurement procedure and the risk of harm from a potentially erroneous result being reported
b. Based on the stability of a measurement procedure
c. Based on the magnitude of the SD used for evaluating QC results
d. Every 24 hours
e. Whenever a result is suspicious

A

A

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7
Q

How should a target value be established for a QC sample?
a. As the mean of the first 25 results
b. As the mean of the first 10 results
c. As the mean from interlaboratory comparison data
d. As the mean of at least 10 results and updated when more results are available
e. As the standard error of the mean of 10 results

A

D

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8
Q

What is the first thing to do when a QC result fails an evaluation rule?
a. Repeat the QC sample
b. Recalibrate then repeat the QC sample
c. Check if the previous QC result was acceptable or not
d. Check if the result from a different QC sample measured at the same time was acceptable or not
e. Stop reporting results for patient samples

A

E

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9
Q

What are the key attributes of a rule used to interpret QC results?
a. The rule should identify a QC result that has a 95% probability of being incorrect.
b. The rule should identify a bias that exceeds the manufacturer’s specification for the measurement procedure.
c. The rule should identify either a bias or an imprecision that exceeds the manufacturer’s specification for the measurement procedure.
d. The rule should identify an error condition that is large enough to increase the risk of an erroneous medical decision based on results for the test.
e. The rule should identify when a measurement procedure is at risk to produce an erroneous result.

A

D

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10
Q
  1. The moving average of patient sample results is useful in which of the following situations?
    a. When there are a large number of results generated in a short time interval
    b. When a physiologically homogeneous population of patients can be identified
    c. When the cost of QC samples is very expensive
    d. When the measurement procedure is very stable after long time intervals
    e. When results can vary within a patient over relatively short time intervals.
A

B

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11
Q

Which of the following usually best describes the variation in the concentration or activity of most measurands in laboratory medicine?
a. Circadian rhythms
b. Monthly cycles
c. Systematic trends
d. Random variation
e. Seasonal fluctuations

A

D

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12
Q

Which of the following describes the most appropriate way to find numerical data on the components of biological variation?
a. Determine these in your own laboratory
b. Use a search engine on the Internet
c. Use databases on specific websites
d. Ask a colleague
e. E-mail a query to an internet forum

A

C

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13
Q

Analytical performance specifications (Select all that apply):
a. Can be calculated using measurement uncertainty.
b. Can be estimated based on biological variation data.
c. Should never be estimated using state of the art of the measurement method.
d. Is not important for setting quality control rules.
e. A measurand can have different analytical performance specifications based on its intended use.

A

B, E

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14
Q

Which of the following is irrelevant to the creation of reference change values?
a. Within-subject biological variation
b. Examination bias
c. Examination imprecision
d. Pre-examination sources of variation
e. Between-subject biological variation

A

E

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15
Q

Which of the following represents the individuality of most measurands in laboratory medicine?
a. The index of individuality is high.
b. The index of individuality is low.
c. The measurand has low individuality.
d. The within-subject variation is larger than the betweensubject variation.
e. The analytical imprecision is lower than the withinsubject variation.

A

B

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16
Q

What are the consequences for the use of the reference change value (RCV) if the applied within-subject variation estimates are derived from a heterogeneously distributed data set?
a. No consequences.
b. The within-subject biological variation will be too high.
c. The RCV can only be used on specific individuals.
d. The RCV is not applicable for use in the general population.
e. The RCV indicates only analytical variation.

A

D

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17
Q

If the difference between two consecutive examination results in a patient is larger than the reference change value (RCV), what does this mean?
a. That there is a medical change in the condition of the patient
b. There is an error in the analytical system
c. That the difference is larger than what can be explained by analytical and biological variation
d. That the patient has a 95% probability of being seriously ill
e. That the patient belongs to another population

A

C

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18
Q

What are the consequences of not excluding outliers within samples of each individual when using this data to estimate biological variation?
a. The reference change value cannot be generalized.
b. You have to log transform the data.
c. The within-subject biological variation will be underestimated.
d. The within-subject biological variation will be overestimated.
e. You cannot use the data for meta-analysis.

A

D

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19
Q

The rationale to set analytical performance specifications based on biology is:
a. To minimize the analytical noise to the biological signal.
b. Because this is the best way to measure patient outcomes.
c. Because most differences between two serial results from a patient can be explained by biological variation.
d. Because otherwise it is not possible to estimate total error.
e. Because it is the easiest way.

A

A

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20
Q

Select all that apply of the following statements.
a. The Biological Variation Data Critical Appraisal Checklist (BIVAC) may be used as a tool to appraise the quality of biological variations studies.
b. The BIVAC primarily focuses on the effect of study design and statistical handling on estimates for between-subject variation.
c. An overall BIVAC grade D indicates that the publication is BIVAC compliant and that data are fit for purpose.
d. The BIVAC consists of 14 quality items.
e. The BIVAC can be used to calculate the withinsubject variation.

A

A,D

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21
Q

Which of the following processes should be followed to achieve more homogeneous populations for reference interval testing?
a. Obtain specimens from additional subjects
b. Repeat analyses on current specimens
c. Transform the current data
d. Partition the current data
e. Find additional outliers among the current data

A

D

22
Q

Which of the following characteristics represents an advantage of the nonparametric technique for determining
reference intervals?
a. It requires a smaller number of specimens than the parametric technique
b. There is no need to qualify subjects for inclusion
c. There is no need to partition the data
d. There is no need to eliminate outliers
e. A Gaussian distribution is not required

A

E

23
Q

Which of the following represents an advantage of the indirect method of determining reference intervals?
a. It can be performed on any population
b. It is less expensive
c. It requires smaller numbers of specimens
d. It does not require partitioning
e. It is most useful for specialist referral laboratories

A

B

24
Q

Which of the following distinguishes clinical decision limits from conventional reference intervals?
a. Outcomes or diagnoses for subjects need to be known
b. They are generally method-dependent
c. Specific percentages of subjects are above and below thresholds
d. They do not require partitioning
e. They are easier to establish

A

A

25
Q

“Subject-based” reference intervals
a. Are obtained from a group of
systematically defined reference individuals
b. Are the type of reference intervals referred to when the “reference interval” is used with no qualifying words
c. Are based on several specimens collected over time in single individuals
d. Represent a random sample of all individuals in the parent population
e. Are particularly useful for tests where the interindividual variability is similar to the inter-individual variability

A

C

26
Q

Ongoing review of the distribution of outpatient data:
a. Represents a standard part of a laboratory quality control program
b. Is required for lab accreditation
c. Is useful to monitor clinical decision limits
d. Can detect drift in analytical methods
e. Requires transforming the data to a Gaussian distribution

A

D

27
Q

The distribution of laboratory data from healthy individuals is often
a. Gaussian
b. Skewed to the right
c. Wider than Gaussian
d. Bimodal
e. Nonparametric

A

B

28
Q

In a patient whose calcium is significantly below the lower reference limit, which of the following tests would be expected to be outside conventional reference limits?
a. Alanine aminotransferase
b. Bilirubin
c. Parathyroid hormone
d. Cortisol
e. Prothrombin time

A

C

29
Q

Which of the following would most likely be used as an exclusion criterion for a reference interval study for serum iron?
a. Age
b. Sex
c. Ethnicity
d. Body mass index
e. Recent transfusion

A

E

30
Q

When reference limits are determined, which of the following methods requires a Gaussian distribution?
a. Nonparametric
b. Parametric
c. Interpercentile
d. Bootstrap
e. Robust

A

B

31
Q

The “active center” of an enzyme is:
a. The part of an enzyme that determines its function
b. The protein part of an enzyme without the cofactor necessary for catalysis
c. The part of an enzyme that diminishes the rate of a chemical reaction
d. A site other than the substrate binding site
e. The part of an enzyme at which substrate binding occurs

A

E

32
Q

Which statement(s) below is (are) correct?
a. Apoenzyme 1 Prosthetic group 5 Holoenzyme
b. An enzyme without the prosthetic group attached is referred to as an apoenzyme
c. A prosthetic group is a coenzyme permanently bound to an enzyme molecule
d. An enzyme can be active without the presence of activator
e. All of the above statements are correct

A

E

33
Q

The graph on which the plot of 1/velocity versus 1/substrate concentration is illustrated is referred to as a:
a. Rate plot
b. Substrate plot
c. Lineweaver-Burk plot
d. Maximum velocity plot
e. Michaelis-Menten plot

A

C

34
Q

Every enzymatic reaction follows specific kinetics as it proceeds from enzyme 1 substrate to product 1 enzyme. As substrate is consumed, the reaction rate decreases and becomes directly proportional to the amount of substrate
that is present in low concentration. This is referred to as:
a. Vmax
b. Km
c. Second-order kinetics
d. First-order kinetics
e. Zero-order kinetics

A

D

35
Q

An international unit (U) of enzyme activity is the amount of enzyme that will catalyze the reaction of:
a. One micromole of substrate per minute
b. One micromole of substrate per second
c. One mole of enzyme per hour
d. One millimole of substrate per minute
e. One millimole of substrate per second

A

A

36
Q

At the top of the traceability chain for enzyme standardization there is:
a. End-user’s field measurement procedure
b. Secondary reference material
c. Reference measurement procedure
d. Routine clinical samples
e. Manufacturer’s commercial calibrator

A

C

37
Q

Which statement regarding enzyme inhibition is correct:
a. A competitive inhibitor binds the ES complex
b. A noncompetitive inhibitor is structurally similar from the substrate
c. Competitive inhibition is always irreversible
d. A competitive inhibitor binds the active center of the enzyme
e. An irreversible inhibitor is in equilibrium with the enzyme

A

D

38
Q

Enzyme reactions are affected by:
a. Substrate concentration
b. pH
c. Enzyme concentration
d. Temperature
e. All of the above

A

E

39
Q

What is the general mechanism of an enzyme?
a. It acts by reducing the activation energy
b. It acts by increasing the activation energy
c. It acts by decreasing the pH
d. It acts by increasing the pH
e. All of the above statements are correct

A

A

40
Q

When the velocity of enzyme activity is plotted against substrate concentration, which of the following curve is obtained:
a. Parabola
b. Rectangular hyperbola
c. Straight line with positive slope
d. Straight line with negative slope
e. Ellipse

A

B

41
Q

Which of the following statements accurately describes antibodies?
a. They contain one heavy chain and two light chains
b. The variable region defines the antibody isotype
c. IgG is used most commonly in immunochemical reagents
d. Monoclonal antibodies are secreted from T-cell clones
e. Polyclonal antibodies can only be produced in mice

A

C

42
Q

Which of the following statements is correct in the context of immunologic reactions?
a. Monoclonal antibodies recognize a single epitope on an antigen
b. A hapten is as a high-MW molecule that can induce an immune response only when coupled to a high-MW molecule
c. The antigen-antibody reaction is irreversible
d. In an antigen assay, the hook effect occurs in the limited antigen phase of the antigen:antibody reaction
e. The Fc region of the immunoglobulin molecule binds to antigens

A

A

43
Q

Which of the following qualitative immunoassay techniques requires transfer of protein to a membrane?
a. Crossed immunoelectrophoresis
b. Immunofixation
c. Dot blotting
d. Double immunodiffusion assay
e. Counterimmunoelectrophoresis

A

C

44
Q

Which one of the following is true about analytical effects of circulating anti-animal antibodies?
a. They only interfere in immunoassays based on a competitive assay design
b. They do not interfere in immunoassays based on a sandwich assay design
c. They do not cause false-negative immunoassay results
d. They only cause false-positive results in ELISA assays
e. They can cause false-negative or false-positive immunoassay results

A

E

45
Q

Which of the following is an example of a homogenous assay?
a. LOCI
b. ELISA
c. Luminex xMAP
d. Electroimmunoassay
e. Western blotting

A

A

46
Q

Which one of the following types of immunoassay requires a separation step?
a. CEDIA
b. ELISA
c. EMIT
d. FPIA
e. LOCI

A

B

47
Q

Which one of the following statements best describes immunoassay
sensitivity?
a. The functional sensitivity of an immunoassay is based on detectability above the assay blank
b. The analytical sensitivity (detection limit) of an immunoassay is defined as the lowest concentration of an assay that can be measured with an interassay coefficient
of variation of 20%
c. In the sandwich assay design, the sensitivity of the label detection reaction plays a minor role in the analytical sensitivity of the assay.
d. The functional sensitivity of an immunoassay is typically a lower concentration than the analytical sensitivity (detection limit) of the immunoassay
e. Nonspecific binding limits the analytical sensitivity of an immunoassay

A

E

48
Q

Which of the following immunoassay labels offers the most sensitivity or lowest detection limit?
a. Europium chelate
b. Horseradish peroxidase
c. Alkaline phosphatase
d. I-125
e. I-131

A

B

49
Q

Which of the following statements is true?
a. A weak color signal in a competitive ELISA signifies a low level of analyte in the sample
b. A weak color signal in a sandwich ELISA signifies a high level of analyte in the sample
c. In a nephelometric immunoassay, the amount of light not obstructed by suspended immune complex
particles is measured
d. In a turbidimetric immunoassay, the amount of light scattered by suspended immune complex particles is measured
e. Protein can be detected by a Western blot

A

E

50
Q

Which of the following statements is true regarding interferences with immunoassays?
a. Immunoassays that use highly specific antibodies are not prone to interferences from exogenous compounds.
b. If an interference is suspected, you should repeat testing at another laboratory using the same assay platform.
c. Immunoassay interferences can only produce falsely low results.
d. Interferences can sometimes be uncovered by using blocking agents.
e. Only antimouse immunoglobulin antibodies have been detected in humans

A

D

51
Q
A

Examen OCQ Biochimie Clinique (15 decks)

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