Test Bank for Clinical Laboratory Chemistry
2nd Edition Sunheimer / All Chapters 1-26
/ Full Complete
Section 1: Fundamentals of Clinical Chemistry
1. Which of the following best defines the term "analyte" in clinical chemistry?
A. The instrument used to measure a substance
B. The chemical reagent added to a sample
C. The substance being measured in a biological specimen
D. The final calculated result reported to the physician
Correct Answer: C
Rationale: An analyte is the specific substance or component being measured in a
laboratory test (e.g., glucose, sodium, creatinine). It is not the instrument, reagent, or result
itself.
2. A 24-hour urine specimen is collected for measurement of a specific analyte. Which of the
following is the most critical step to ensure accurate results?
A. Keeping the specimen at room temperature
B. Recording the total volume and mixing the specimen thoroughly before aliquoting
C. Adding a preservative to the container after collection
D. Filtering the specimen before analysis
Correct Answer: B
Rationale: For 24-hour urine collections, the total volume must be accurately measured,
and the specimen must be well-mixed to ensure the aliquot is representative of the entire
collection. Preservatives are typically added before collection, not after.
3. Which of the following is an example of a primary standard?
A. A control material with an assigned value
B. A substance of known high purity used to calibrate an assay
C. A patient sample with a known diagnosis
D. A reagent blank
Correct Answer: B
Rationale: A primary standard is a highly purified substance that can be weighed accurately
,to prepare a solution of exact known concentration. It is used to calibrate or standardize
analytical methods.
4. The term "accuracy" in clinical chemistry refers to:
A. The closeness of a measured value to the true value
B. The closeness of repeated measurements to each other
C. The ability to detect small amounts of an analyte
D. The linear range of an assay
Correct Answer: A
Rationale: Accuracy is the agreement between a measured value and the true (or accepted)
value. Precision, in contrast, refers to the reproducibility of repeated measurements.
5. Which of the following units is used to express the concentration of most analytes in
clinical chemistry in the United States?
A. Milligrams per deciliter (mg/dL)
B. Millimoles per liter (mmol/L)
C. International units per liter (IU/L)
D. Nanograms per milliliter (ng/mL)
Correct Answer: A
Rationale: In the United States, mg/dL is the traditional unit for many analytes (e.g.,
glucose, cholesterol, creatinine). SI units (mmol/L) are used in many other countries and
increasingly in the U.S.
6. What is the purpose of a "blank" in spectrophotometric analysis?
A. To zero the instrument and correct for absorbance due to reagents and cuvettes
B. To provide a positive control
C. To calibrate the wavelength
D. To measure the analyte directly
Correct Answer: A
Rationale: A reagent blank contains all reagents except the sample. It is used to zero the
spectrophotometer, correcting for any absorbance from reagents, solvent, or the cuvette itself.
7. Which of the following is a pre-analytical error?
A. Using an expired reagent
B. Mislabeling a patient sample
C. Incorrectly calibrating the instrument
D. Reporting a critical value incorrectly
, Correct Answer: B
Rationale: Pre-analytical errors occur before sample analysis and include patient
identification errors, improper collection, mislabeling, and improper storage/transport. Using
expired reagents and calibration errors are analytical errors.
8. The molecular weight of glucose is 180 g/mol. What is the conversion factor to convert
mg/dL to mmol/L?
A. 0.0555
B. 18
C. 0.0111
D. 180
Correct Answer: A
Rationale: To convert mg/dL to mmol/L for glucose: (mg/dL × 10) / molecular weight =
(mg/dL × 10) / 180 = mg/dL × 0.0555. For example, 100 mg/dL × 0.0555 = 5.55 mmol/L.
9. Which of the following best describes a "critical value" in clinical chemistry?
A. Any value outside the reference interval
B. A value that requires immediate notification of the physician because it may be life-
threatening
C. The highest value on the calibration curve
D. A value that is statistically insignificant
Correct Answer: B
Rationale: A critical value (or panic value) is a result that is significantly outside the normal
range and may indicate a life-threatening condition. It requires immediate communication to
the healthcare provider.
10. Which of the following is true regarding the chain of custody for a specimen?
A. It is only required for blood bank specimens
B. It documents the chronological history of specimen handling and is required for forensic or
legal testing
C. It is optional for all clinical testing
D. It is only used for urine drug testing
Correct Answer: B
Rationale: Chain of custody is a documented record of who handled the specimen, when,
and for what purpose. It is essential for forensic, legal, and workplace drug testing to ensure
specimen integrity.
, 11. The term "turnaround time" (TAT) in the clinical laboratory refers to:
A. The time it takes to calibrate an instrument
B. The time from specimen collection to result reporting
C. The time required to perform a single test
D. The time between instrument maintenance checks
Correct Answer: B
Rationale: TAT is the total time from when a test is ordered or specimen collected until the
result is reported to the clinician. It is a key performance indicator for laboratory efficiency.
12. Which of the following is an example of a point-of-care test (POCT)?
A. Serum creatinine measured on a large automated analyzer
B. Blood glucose measured with a handheld glucometer at the patient's bedside
C. Comprehensive metabolic panel sent to a reference laboratory
D. Urine culture performed in the microbiology lab
Correct Answer: B
Rationale: POCT is performed near the patient, often by non-laboratory personnel.
Handheld glucometers are a common example. They provide rapid results but require strict
quality control.
Section 2: Laboratory Safety and Specimen Collection
13. Which of the following is the most appropriate action if a blood specimen tube breaks on
the laboratory floor?
A. Pick up the pieces with gloved hands and discard in a regular trash can
B. Evacuate the area, notify safety personnel, and use a spill kit to clean up while wearing
appropriate PPE
C. Wipe up the spill with a paper towel and discard in a biohazard bag
D. Spray the area with bleach and leave it to dry
Correct Answer: B
Rationale: A broken blood tube is a biohazard. The area should be evacuated, and trained
personnel using a spill kit and PPE should clean it. Never pick up broken glass with gloved hands.
14. Which of the following is the correct order of draw for venipuncture using the evacuated
tube system?
A. Lavender (EDTA), Gold (SST), Light Blue (Citrate), Green (Heparin)
B. Blood culture, Light Blue (Citrate), Gold (SST), Green (Heparin), Lavender (EDTA)
2nd Edition Sunheimer / All Chapters 1-26
/ Full Complete
Section 1: Fundamentals of Clinical Chemistry
1. Which of the following best defines the term "analyte" in clinical chemistry?
A. The instrument used to measure a substance
B. The chemical reagent added to a sample
C. The substance being measured in a biological specimen
D. The final calculated result reported to the physician
Correct Answer: C
Rationale: An analyte is the specific substance or component being measured in a
laboratory test (e.g., glucose, sodium, creatinine). It is not the instrument, reagent, or result
itself.
2. A 24-hour urine specimen is collected for measurement of a specific analyte. Which of the
following is the most critical step to ensure accurate results?
A. Keeping the specimen at room temperature
B. Recording the total volume and mixing the specimen thoroughly before aliquoting
C. Adding a preservative to the container after collection
D. Filtering the specimen before analysis
Correct Answer: B
Rationale: For 24-hour urine collections, the total volume must be accurately measured,
and the specimen must be well-mixed to ensure the aliquot is representative of the entire
collection. Preservatives are typically added before collection, not after.
3. Which of the following is an example of a primary standard?
A. A control material with an assigned value
B. A substance of known high purity used to calibrate an assay
C. A patient sample with a known diagnosis
D. A reagent blank
Correct Answer: B
Rationale: A primary standard is a highly purified substance that can be weighed accurately
,to prepare a solution of exact known concentration. It is used to calibrate or standardize
analytical methods.
4. The term "accuracy" in clinical chemistry refers to:
A. The closeness of a measured value to the true value
B. The closeness of repeated measurements to each other
C. The ability to detect small amounts of an analyte
D. The linear range of an assay
Correct Answer: A
Rationale: Accuracy is the agreement between a measured value and the true (or accepted)
value. Precision, in contrast, refers to the reproducibility of repeated measurements.
5. Which of the following units is used to express the concentration of most analytes in
clinical chemistry in the United States?
A. Milligrams per deciliter (mg/dL)
B. Millimoles per liter (mmol/L)
C. International units per liter (IU/L)
D. Nanograms per milliliter (ng/mL)
Correct Answer: A
Rationale: In the United States, mg/dL is the traditional unit for many analytes (e.g.,
glucose, cholesterol, creatinine). SI units (mmol/L) are used in many other countries and
increasingly in the U.S.
6. What is the purpose of a "blank" in spectrophotometric analysis?
A. To zero the instrument and correct for absorbance due to reagents and cuvettes
B. To provide a positive control
C. To calibrate the wavelength
D. To measure the analyte directly
Correct Answer: A
Rationale: A reagent blank contains all reagents except the sample. It is used to zero the
spectrophotometer, correcting for any absorbance from reagents, solvent, or the cuvette itself.
7. Which of the following is a pre-analytical error?
A. Using an expired reagent
B. Mislabeling a patient sample
C. Incorrectly calibrating the instrument
D. Reporting a critical value incorrectly
, Correct Answer: B
Rationale: Pre-analytical errors occur before sample analysis and include patient
identification errors, improper collection, mislabeling, and improper storage/transport. Using
expired reagents and calibration errors are analytical errors.
8. The molecular weight of glucose is 180 g/mol. What is the conversion factor to convert
mg/dL to mmol/L?
A. 0.0555
B. 18
C. 0.0111
D. 180
Correct Answer: A
Rationale: To convert mg/dL to mmol/L for glucose: (mg/dL × 10) / molecular weight =
(mg/dL × 10) / 180 = mg/dL × 0.0555. For example, 100 mg/dL × 0.0555 = 5.55 mmol/L.
9. Which of the following best describes a "critical value" in clinical chemistry?
A. Any value outside the reference interval
B. A value that requires immediate notification of the physician because it may be life-
threatening
C. The highest value on the calibration curve
D. A value that is statistically insignificant
Correct Answer: B
Rationale: A critical value (or panic value) is a result that is significantly outside the normal
range and may indicate a life-threatening condition. It requires immediate communication to
the healthcare provider.
10. Which of the following is true regarding the chain of custody for a specimen?
A. It is only required for blood bank specimens
B. It documents the chronological history of specimen handling and is required for forensic or
legal testing
C. It is optional for all clinical testing
D. It is only used for urine drug testing
Correct Answer: B
Rationale: Chain of custody is a documented record of who handled the specimen, when,
and for what purpose. It is essential for forensic, legal, and workplace drug testing to ensure
specimen integrity.
, 11. The term "turnaround time" (TAT) in the clinical laboratory refers to:
A. The time it takes to calibrate an instrument
B. The time from specimen collection to result reporting
C. The time required to perform a single test
D. The time between instrument maintenance checks
Correct Answer: B
Rationale: TAT is the total time from when a test is ordered or specimen collected until the
result is reported to the clinician. It is a key performance indicator for laboratory efficiency.
12. Which of the following is an example of a point-of-care test (POCT)?
A. Serum creatinine measured on a large automated analyzer
B. Blood glucose measured with a handheld glucometer at the patient's bedside
C. Comprehensive metabolic panel sent to a reference laboratory
D. Urine culture performed in the microbiology lab
Correct Answer: B
Rationale: POCT is performed near the patient, often by non-laboratory personnel.
Handheld glucometers are a common example. They provide rapid results but require strict
quality control.
Section 2: Laboratory Safety and Specimen Collection
13. Which of the following is the most appropriate action if a blood specimen tube breaks on
the laboratory floor?
A. Pick up the pieces with gloved hands and discard in a regular trash can
B. Evacuate the area, notify safety personnel, and use a spill kit to clean up while wearing
appropriate PPE
C. Wipe up the spill with a paper towel and discard in a biohazard bag
D. Spray the area with bleach and leave it to dry
Correct Answer: B
Rationale: A broken blood tube is a biohazard. The area should be evacuated, and trained
personnel using a spill kit and PPE should clean it. Never pick up broken glass with gloved hands.
14. Which of the following is the correct order of draw for venipuncture using the evacuated
tube system?
A. Lavender (EDTA), Gold (SST), Light Blue (Citrate), Green (Heparin)
B. Blood culture, Light Blue (Citrate), Gold (SST), Green (Heparin), Lavender (EDTA)
