(Test Bank) Tietz Fundamentals Of Clinical Chemistry And Molecular Diagnostics

Burtis, 7

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7th Edition

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Tietz Fundamentals of Clinical Chemistry and Molecular Diagnostics 7th Edition Burtis Test Bank Chapter 01: Clinical Chemistry, Molecular Diagnostics, and Laboratory Medicine Test Bank MULTIPLE CHOICE 1. An individual working in a clinical chemistry laboratory is married to a sales representative who works for a company that sells chemistry laboratory supplies. When the laboratory manager requests a lis t of needed supplies, cost of supplies, and vendors, this individual only recommends the spouse’s company as the vendor. This is considered to be a(n): a. accounting issue. b. possible conflict of interest. c. maintenance of confidentiality issue. d. problem with resource allocation. ANS: B Concern has been raised over the interrelationships between practitioners in the medical field and commercial suppliers of drugs, devices, equipment, etc., to the medical profession. Similarly, relationships have been scrutinized between clinical laboratorians and manufacturers and providers of diagnostic equipment and supplies. These concerns led the National Institutes of Health (NIH) in 1995 to require official institutional review of financial disclosure by researchers and management of situations in which disclosure indicates potential conflicts of interest. DIF: 1 REF: Page 4 -5 OBJ: 6 | 7 2. A patient visits her physiciTanEsStaTtiBnAg NthKatShEerLpLreEsRcr.ibCeOd Mpainkill er is not working to r educe the pain following her recent surgery. A friend of the patient claims that the same painkiller “worked wonders” to reduce her pain after the same surgery. The physician states that the difference in the effect of the drug might be caused by , which is studied in pharmacogenetics. a. epidemiology b. an inherited disease c. a conflict of interest d. a genetic variation in drug-metabolizing enzymes ANS: D Pharmacogenetics is the study of the genetic variation of drug metabolism between individuals. DIF: 1 REF: Page 3 OBJ: 1 3. John works in a molecular diagnostics laboratory and receives a blood sample that has the name of a close friend printed on the bar-coded label. The genetic test that is ordered on the friend’s sample would provide diagnostic information about a disorder that has a poor prognosis, and the test is usually performed by John. He asks a fellow employee to analyze the sample for him and not divulge the results. This ethical issue concerns: a. confidentiality of patient genetic and medical information. b. a conflict of interest. c. resource allocation. d. diagnostic accuracy. ANS: A Clinical laboratorians have long been responsible for maintaining the confidentiality of all labor atory results, a situation made even more critical with the advent of increasingly powerful genetic testing. DIF: 1 REF: Page 4 OBJ: 6 | 7 4. Molecular diagnostic testing methods and results can be: a. qualitative only. b. quantitative only. c. either qualitative or quantitative. ANS: C Molecular diagnostic methods can be either qualitative or quantitative in nature, depending on the clinical need. DIF: 1 REF: Page 3 OBJ: 5 5. Clinical epidemiology, which is the study of the patterns, causes, and effects of health and disease in certain populations, has provided the clinical laboratory with methods that evaluate the effects and outcomes of laboratory testing. This allows for a more effective: a. process of determining the cost of the testing methods. b. selection and interpretation of laboratory tests. c. determination of the boundaries between the components of the clinical lab. d. conduct assessment. ANS: A Clinical epidemiologists have introduced methods to evaluate the effects and value of laboratory testing in healthcare. These developments are expected to play an increasing role in the selection and interpretation of laboratory tests. DIF: 1 REF: Page 3 OBJ: 4 6. Analysis of which one of the following by molecular diagnostic methods provides a measure of processes that are ongoing at the time of blood sampling? a. Genetic variation in an individual’s response to a drug b. Circulating plasma nucleic acids c. Malignant lymphomas d. Histocompatibility ANS: B Molecular diagnostics, given its very high sensitivity, has been applied to the study of plasma nucleic acids (or circulating nucleic acids). Plasma nucleic acids analysis has been made possible by the discovery that dying cells in the body release their DNA and RNA into the extracellular compartment and ultimately into the bloodstream, where they can be detected and analyzed. Given their short half -life in circulation (less than 24 hours), plasma nucleic acids provide a measure of processes that are ongoing at the time of blood sampling. DIF: 1 REF: Page 3 OBJ: 5 7. A healthy individual with no clinical signs or symptoms of disease visits his physician for a routine physical examination. Blood samples are collected and sent to the laboratory. The tests requested on the sample are for general laboratory analyses, inclu ding a complete blood count, a panel of general chemistry tests (including glucose, protein, cholesterol, and others), and an analysis of urine. This type of testing in laboratory medicine is directed at: a. confirming a clinical suspicion of disease. b. selecti ng a treatment for disease. c. ruling in a diagnosis. d. screening for disease in the absence of clinical signs or symptoms. ANS: D Testing in laboratory medicine may be directed at (1) confirming a clinical suspicion; (2) making, or ruling in, a diagnosis; (3) excluding, or ruling out, a diagnosis;, (4) assisting in the selection, optimization, and monitoring of treatment; (5) providing a prognosis ; (6) screening for disease in the absence of clinical signs or symptoms; or (7) establishing and mon itoring the severity of a physiologic disturbance. The field of laboratory medicine includes clinical chemistry and areas such as microbiology and hematology. The general tests ordered on this healthy individual are done to screen the physiologic systems d espite the absence of any symptoms. DIF: 2 REF: Page 2 OBJ: 2 8. The discipline involved in the selection, provision, and interpretation of diagnostic testing that uses primarily samples from patients is: a. clinical chemistry. b. hematology. c. laboratory medicine. d. molecular diagnostics. ANS: C The term “laboratory medicine” refers to the discipline involved in the (1) selection, (2) provision, and (3) interpretation of diagnostic testing that uses prima rily samples from patients. DIF: 1 REF: Page 1 OBJ: 1 | 3 9. A male laboratorian works in the clinical chemistry laboratory of a large hospital. He is approached by his friend, who is a representative of a drug company, and asked to analyze some patient samples for drug levels of a specific drug that the representative’s company sells and that these patients use. The representative wants to publish a report on the rate of drug absorption and distribution of this drug and tells his laboratorian friend that he will personally reimburse him for his time. What ethical issues come into play here? a. Resource allocation and conflict of interest b. Maintenance of confidentiality and publishing issues c. Maintenance of confidentiality, conflict of interest, and publishing issues. d. Resource allocation, maintenance of confidentiality, conflict of interest, and publishing issues. ANS: D Resource allocation, maintenance of confidentiality, conflict of interest, and publishing issues are being compromised by the representative and the laboratorian if the laboratorian follows through with the request. Using laboratory resources for a study that has not been approved by the institutional review board is a resource allocation issue, revealing results of laboratory tests is a confidentiality issue, receiving money to run laboratory tests from an individual with a direct interest in the laborator y results is a conflict of interest, and publishing the results of the testing would possibly be considered fraudulent and inappropriate. DIF: 2 REF: Page 4 -5 OBJ: 3 | 6 | 7 TRUE/FALSE 1. Molecular diagnostics testing is only used by the clinical chemistry laboratory. ANS: F The discipline of molecular diagnostics, which entered the realm of laboratory medicine in multiple forms and in multiple fields, includes but is not limited to the study of hematopoietic malignancies, such as malignant lymphomas and leukemias; the existence of nonhost nucleic acids (microorganisms, graft -donor, fetal nucleic acids during pregna ncy); and assessment of solid tumors. DIF: 1 REF: Page 3 OBJ: 1 | 5 Chapter 02: Selection and Analytical Evaluation of Methods—With Statistical Techniques Test Bank MULTIPLE CHOICE 1. A statistic is a: a. constant that describes some particular characteristic of a population. b. value calculated from the observations in a sample to describe a particular characteristic of that sample. c. complete set of all observations that might occur as a result of performing a particular procedure according to specified conditions. d. graphic device for displaying a large set of data. ANS: B A statistic is a descriptive measure of a sample; it is a value calculated from the observations in a sample to describe a particular characteristic of that sample. DIF: 1 REF: Page 10 OBJ: 3 2. A population mean (µ) is calculated by which one of the following formulae? a. xi/N b. (b − 1)/SE( b) c. (x2i − x1i) d. (x1 − )2/N ANS: A The parameter most commonly used to describe the central location of a population of N values is the population mean (): DIF: 1 REF: Page 10 OBJ: 3 | 11 3. Which one of the following is the correct formula for calculating the percent coefficient of variation of a set of measurements? a. CV = standard deviation  100% b. CV = standard deviation ÷ 100% c. CV = (standard deviation ÷ mean)  100% d. CV = (mean + standard deviation) ÷ 100% ANS: C The coefficient of variation is the measure of relative imprecision. The value of CV% is determined by calculating the ratio of the SD to the m ean multiplied by 100%. DIF: 1 REF: Page 10 OBJ: 11 4. The type of method comparison that compares the average results between two analyses with the differences between varying concentration values of the two analyses is referred to as a(n): a. Deming analysis. b. linear regression plot. c. ordinary least-squares plot. d. Bland -Altman difference plot. ANS: D When comparing values obtained with two different methodologies, the average values of the results are plotted against the differences between the values obtained from the two methods. This examines the differences at varying analyte concentrations to dete rmine whether a problem exists at a certain concentration. DIF: 2 REF: Page 19 OBJ: 1 | 6 5. How is the formula for population standard deviation ( ) stated? a. The positive square root of the mean ÷ sum of squared differences between mean and individual values b. Square root of the mean ÷ (N − 1) c. The positive square root of the [(sum of squared differences between mean and individual values) ÷ N] d. The sum of squared differences ÷ the positive square root of the mean ANS: C Standard deviation describes the dispersion (or variance) of values around a central point (typically the mean). Variance is calculated by summing the squared differences between the population mean and each individual sample value and dividing this sum by the population size. This results in a large number, thus SD is the positive square root of this variance. DIF: 1 REF: Page 10 OBJ: 1 | 11 6. Two types of error may be encountered during analysis of a substance. The type of error that occurs with a constant or predictable difference or trend, either positive or negative, and thus is related to bias, is a(n) error. a. systematic b. random c. analytical d. All of the above are correct. ANS: A Systematic error is a component of error, which in the course of a number of analyses of the same measure and/or analyte remains constant or varies in a predictable (proportional) way. This type of error will directly influence the mean value and affects bias. DIF: 2 REF: Page 7 OBJ: 1 | 7 7. A research project examining cholesterol values using a new Cholestcheck assay produces the following cholesterol values from a random sample of 14, 25-year-old women: Mean = 137 mg/dL 2 standard deviations = 6 mg/dL N = 14 The coefficient of variation percent for this assay is: a. 1.14%. b. 2.19%. c. 4.38%. d. 9.49%. ANS: B CV% is calculated by dividing a standard deviation by the mean and then multiplying that value by 100%. In this case, one standard deviation is equal to 3 mg/dL (6 mg/dL ÷ 2), which is divided by 137 and equals 0.02189. This value multiplied by 100% equals 2.189 or 2.19. DIF: 2 REF: Page 20 OBJ: 11 8. You are performing a precision study on a new chemistry analyzer in your hospital lab by analyzing a single sample many times. The study involves performing the analysis on different shifts using different calibrators and analysis by different laboratorian s. This aspect of precision is referred to as: a. repeatability. b. reproducibility c. validity. d. reliability. ANS: B One aspect of precision is reproducibility, the closeness of agreement between results of measurements performed under changed conditions of measurements (e.g., time, operators, calibrators, and reagent lots). DIF: 2 REF: Page 13 OBJ: 1 | 4 9. Following a precision study in which repeatability and reproducibility of 20 samples are assess ed, whi ch one of theTfoElSloTwBinAgNfoKrmSEulLaeLwEoRu.ldCbOeMused to det ermine the total stand ard deviation (2T)? a. 2within -run/2 + 2 b. (x2i − x1i) c. (x1 − )2/N d. 2within -run + 2 ANS: D The degree of precision is usually expressed on the basis of statistical measures of imprecision, such as the standard deviation. The total standard deviation ( 2T) may be split into within -run and between -run components using the principle of analysis of variance components (variance is the squared standard deviation): 2T = 2within -run + 2 DIF: 2 REF: Page 13 OBJ: 4 | 11 10. The ability of an analytical method to assess small variations of the concentration of an analyte, and that is often expressed as the slope of the calibration curve, is referred to as: a. analytical specificity. b. analytical sensitivity. c. limit of detection. d. analytical range. ANS: B between -run between -run between -run Analytical sensitivity is the ability of an analytical method to assess small variations of the concentration of analyte. This is often expressed as the slope of the calibration curve. DIF: 1 REF: Page 6 OBJ: 1 | 4 11. Method selection involves consideration of several different criteria. Assessment of a candidate method’s precision, accuracy, and analytical specificity are components of which one of the following categories? a. Analytical performance criteria b. Medical criteria c. Instrument parameters d. Descriptive measures criteria ANS: A In evaluation of the performance characteristics of a candidate method, precision, accuracy (trueness), analytical range, detection limit, and analytical specificity are of prime importance. These are aspects of analytical performance criteria. DIF: 1 REF: Page 7 -8 OBJ: 2 12. The statistical analysis used to compare values obtained by a new method with those obtained by an established method is: a. a Student t test. b. standard deviation. c. regression analysis. d. limit of detection. ANS: C Regression analysis is commonly applied when comparing the results of analytical method comparisons. Typically an experiment is carried out in which a series of paired values is collected when comparing a new method with an established method. DIF: 1 REF: Page 20 OBJ: 1 | 5 13. The Student t distribution: a. compares a sample mean to a population mean using the population. b. compares the means of two samples using sample statistics. c. assesses the means of samples prior to and following some intervention. d. assesses the significance of difference between more than two variables. ANS: B A Student t distribution analysis is commonly used in significance tests, such as the comparison of sample means. Therefore, if a random sample can be taken from a Gaussian population, then the sample SD can be calculated from the sample means. DIF: 2 REF: Page 11 OBJ: 1 | 3 14. A list of intervals followed by a list of frequencies is referred to as a: a. frequency histogram. b. range. c. cumulative frequency distribution. d. frequency distribution. ANS: D A frequency distribution is constructed by dividing the measurement scale into cells of equal width; counting the number, ni, of values that fall within each cell; and either drawing a histogram or listing the number of values in each cell. DIF: 1 REF: Page 9 OBJ: 1 15. The type of regression analy sis that is considered to reliably estimate the relationship between modified target values and that takes into account errors in both methods 1 and 2 is regression analysis. a. Deming b. ordinary least-squares c. nonparametric d. random error ANS: A To reliably estimate the relationship between modified target values, a regression procedure taking into account errors in both x1 and x2 is preferable (a situation termed the Deming approach ). Although the OLR procedure is commonly used in method comparison studies, it does not take errors in x1 into account but is based on the assumption that only the x2 measurements are subject to random errors. DIF: 2 REF: Page 21 OBJ: 8 16. Comparisons of measurement values between clinical laboratories require a hierarchical approach that obliges routine clinical chemistry measurements to be referred back to a reference measurement proTcEedSuTreB. TAhNisKcSoEncLeLptEiRs .knCoOwMn as: a. uncertainty. b. error. c. traceability. d. reliability. ANS: C To ensure reasonable agreement between measurements of routine methods, the concept of traceability comes into focus. Traceability is based on an unbroken chain of comparisons of measurements leading to a known reference value. A hierarchy of methods exist s with a reference measurement procedure at the top, selected measurement procedures at an intermediate level, and finally routine measurement procedures at the bottom. DIF: 2 REF: Page 28 OBJ: 1 | 9 17. To systematically assess errors associated with laboratory results, a parameter associated with the result of a measurement that characterizes the dispersion of the values reasonably attributed to the substance being measured is considered. This parameter is expressed by a formula that includes preanalytical, analytical, and traceability components and is referred to as: a. uncertainty. b. error. c. traceability. d. reliability. ANS: A To assess in a systematic way errors associated with laboratory results, the uncertainty concept has been introduced into laboratory medicine. The formal definition of uncertainty is “a parameter associated with the result of a measurement that characteriz es the dispersion of the values that could reasonably be attributed to the measurand.” DIF: 1 REF: Page 29 OBJ: 1 | 11 18. In a chemistry methods analysis, linearity refers to the: a. closeness of agreement between independent results of measurements obtained under stipulated conditions. b. closeness of agreement between the average value obtained from a large series of results of measurements and a true value. c. analyte concentration range over which measurements are within the declared tolera nces for imprecision and bias of the method. d. relationship between measured and expected values over the range of analytical measurements. ANS: D Definition: linearity refers to the relationship between measured and expected values over the range of analytical measurements. DIF: 1 REF: Page 13 OBJ: 1 | 4 19. In the calibration hierarchy, a reference measurement procedure, which is a fully understood procedure of highest analytical quality, is at the top. This procedure is associated with which one of the following types of error? a. Calibration error b. Specificity error c. Pure random error d. Systematic error ANS: C A reference measurement procedure is associated only with pure, random error, whereas a routine method typically has some additional bias related to errors in calibration and limitations with regard to specificity. DIF: 1 REF: Page 16 OBJ: 9 20. In a qualitative point -of-care test, clinical sensitivity is considered as the: a. probability of classifying a result as positive. b. probability of classifying a result as negative. c. ability of an analytical method to assess small variations of the concentration of an analyte. d. ability of an assay procedure to determine specifically the concentration of the target analyte in the presence of potentially interfering substances. ANS: A Qualitative point -of-care tests are primarily assessed on the basis of their ability to correctly classify results in relation to the cutoff value. The probability of classifying a result as positive is called the clinical sensitivity , while c lassifying a result as negative (below the cutoff) is termed the clinical specificity . DIF: 1 REF: Page 15 OBJ: 1 Chapter 03: Clinical Evaluation of Methods Test Bank MULTIPLE CHOICE 1. True negatives ÷ (false positives + true negatives) is the formula for determining: a. sensitivity. b. specificity. c. the odds ratio. d. the likelihood ratio. ANS: B Clinical specificity is the absence of a particular disease in those individuals who have a negative test result for that disease expressed as a percentage. DIF: 1 REF: Page 33 OBJ: 2 2. The proportion of a population that has the particular disease being studied is referred to as the: a. prevalence. b. predictive value. c. positive value. d. clinical sensitivity. ANS: A Prevalence is the proportion of the population (or of those being tested) with the disease. DIF: 1 REF: Page 35 OBJ: 1 3. What is the positive predictive value of a test in which 220 tested individuals with positive test results actually have the disease and 45 tested individuals with positive test results do not have the disease? a. 16.9% b. 66% c. 83% d. 120% ANS: C The predictive value for a positive test examines the number of true positives (TP) and false positives (FP). The formula for calculating the predictive value is TP/(TP + FP). In this case, 220/(220 + 45)  100% = 83%. DIF: 3 REF: Page 35 OBJ: 2 4. In regard to the number of true-positive and negative, and false -positive and negative, results in laboratory testing, the prevalence times the sensitivity is equal to the number of: a. true positives. b. false positives. c. true negatives. d. false negatives. ANS: A Prevalence is the proportion of the population (or of those being tested) with the disease while sensitivity of an assay is the fraction of those subjects with a specific disease that the assay correctly predicts. The two values multiplied together is equal to the number of true -positive results (those with the disease that the assay accurately predic ts). DIF: 2 REF: Page 36 OBJ: 5 5. Calculate the sensitivity for the following data: in a group of 80 patients diagnosed with sickle cell disease, 72 tested positively for it. The sensitivity of this test is: a. 111%. b. 100%. c. 90%. d. 75%. ANS: C Sensitivity is the presence of a particular disease in those individuals who have a positive test result for that disease expressed as a percentage. In this case, 72/(72+8)  100% = 90%. DIF: 3 REF: Page 33 OBJ: 2 6. A receiver operating characteristic (ROC) curve is a plot of: a. systematic error against random error. b. tumor marker decision levels versus upper limit of reference intervals. c. true positives versus false positives. d. specificity of one method against the specificity of another method. ANS: C In evaluating performance of different analyses for one analyte or multiple markers for one type of cancer, a plot of the performance of each analysis is made with the x-axis as the fraction of nondiseased patients who were erroneously categorized as posit ive for a specific decision threshold. This “false -positive rate” is mathematically the same as 1 − specificity. The y-axis plots the “true -positive rate” (the sensitivity). DIF: 2 REF: Page 34 -35 OBJ: 1 | 6 7. ROC curves are most useful in assessing the performance of quantitative laboratory analyses because: a. multiple tests for the same analyte can be evaluated at one time. b. they can display performance of tests over the entire range of decision values. c. they allow specific reference intervals to be determined for each analysis. d. they can evaluate combination testing in a single plot. ANS: B A graphical technique for displaying quantitative test performance is called a receiver operating characteristic (ROC) plot. An ROC curve is generated by plotting sensitivity (y-axis) versus 1 − specificity (x-axis) and allows for estimation of sensitivity and specificity for various decision cutoffs. DIF: 2 REF: Page 34 -35 OBJ: 1 | 6 8. A laboratory analysis that produces quantitative results with an infinite number of sensitivity and specificity pairs is referred to as a test. a. predictive b. qualitative c. dichotomous d. continuous ANS: D As opposed to dichotomous tests, continuous tests are those that produce quantitative results. Continuous tests have an infinite number of sensitivity and specificity pairs, as the cutoff varies from lowest to highest decision value. DIF: 1 REF: Page 34 OBJ: 4 9. Nondiseased individuals that are classified as diseased by having a positive result on a specific laboratory test are considered: a. true positives. b. false positives. c. true negatives. d. false negatives. ANS: B False positives (FP) are nondiseased individuals misclassified by a positive laboratory test result. DIF: 1 REF: Page 33 OBJ: 1 10. Combin ation testing inv olvTeEs SthTe BusAeNoKf SmEulLtiLplEe Rla.boCrOatMory tests in an attempt to de crease costs or assist in diagnosing a specific disease. One of the problems with this type of testing is that: a. false -positive results increase. b. true-negative results increase. c. the prevalence of the disease increases. d. the predictive value of a negative test increases. ANS: A The use of multiple tests can increase the probability of the occurrence of false -positive o r false -negative results, depending on how the tests are combined. DIF: 1 REF: Page 37 OBJ: 9 11. A method that can be used to calculate the probability of a disease after new information is added to previously obtained information involves: a. likelihood analysis. b. sensitivity analysis. c. Bayes theorem. d. combination testing. ANS: C Bayes theorem provides a method to calculate the probability of a disease after new information is added to previously obtained information. DIF: 1 REF: Page 36 OBJ: 7 12. To calculate the sensitivity of a laboratory test to correctly classify true positives, one must first know the number of: a. true positives and false negatives. b. true negatives and false positives. c. true positives and false positives. d. false positives and false negatives. ANS: A The sensitivity of a laboratory test reflects the fraction of those with a specified disease that the test correctly predicts. True positives are those diseased individuals who are correctly classified by the test. Sensitivity is calculated by dividing the true positives by the total of true positives plus false negatives. DIF: 2 REF: Page 33 OBJ: 2 13. To calculate the predictive value of a positive test, which of the following should be known? a. Sensitivity only b. Specificity and prevalence only c. Sensitivity and specificity only d. Sensitivity, specificity, and prevalence ANS: D Predictive values are a function of sensitivity, specificity, and prevalence. For example, to determine the predictive value of a positive test (PV+), the prevalence must be known to assess the sensitivity (true positives) of a laboratory test and the specificity (false positives) of the test. The formula for caTlcEuSlaTtiBngAtNheKPSVE+LiLnvEoRlv.esCdOivMiding the numb er of true positiv es by the number of true positives plus the number of false positives. DIF: 2 REF: Page 35 OBJ: 5 14. The probability of occurrence of a specific test value given that the disease is present divided by the probability of the same test value if the disease was absent is the: a. odds ratio. b. likelihood ratio. c. prevalence. d. predictive value. ANS: B The likelihood ratio is the probability of occurrence of a specific test value given that the disease is present divided by the probability of the same test value if the disease was absent. DIF: 1 REF: Page 33 OBJ: 1 TRUE/FALSE 1. In regard to clinical evaluation of method, a high clinical sensitivity means few false negatives. ANS: T