FISCHBACH'S A MANUAL OF
LABORATORY AND DIAGNOSTIC TESTS.
11TH EDITION
• AUTHOR(S)FRANCES FISCHBACH;
MARGARET FISCHBACH; KATE STOUT
TEST BANK
1
Reference
Ch. 1 — Diagnostic Testing
Stem
A 62-year-old man is scheduled for fasting glucose and lipid
studies this morning. He reports drinking coffee with cream 30
minutes ago and took his usual morning insulin. Which nursing
action best addresses preanalytic factors that could invalidate
the test results?
A. Proceed with specimen collection; note the coffee and insulin
on the lab requisition.
B. Delay specimen collection until the patient has been fasting
,for the required interval and notify provider about insulin
timing.
C. Collect the specimen immediately because coffee does not
alter glucose enough to matter.
D. Ask the patient to exercise for 10 minutes then collect the
specimen to reduce stress-related glucose changes.
Correct answer
B
Rationales
• Correct (B): Fasting requirements and recent insulin use
are preanalytic variables that significantly affect glucose
and lipid results. Delaying collection to achieve an
appropriate fasting interval (and informing the provider)
preserves result validity and patient safety.
• Incorrect (A): Simply documenting the preanalytic
violation does not correct the result; the sample may be
clinically misleading and should be deferred or repeated
per policy.
• Incorrect (C): Coffee with cream (carbohydrate/fat) and
recent insulin both can alter glucose and lipid values;
proceeding risks inaccurate interpretation.
• Incorrect (D): Exercise acutely alters glucose and other
metabolic parameters; it introduces another confounder
rather than resolving the fasting violation.
,Teaching point
Confirm and enforce test preparation (fasting, medication
timing) before specimen collection.
Citation
Fischbach, F., Fischbach, M., & Stout, K. (2021). A Manual of
Laboratory and Diagnostic Tests (11th ed.). Ch. 1.
2
Reference
Ch. 1 — Diagnostic Testing
Stem
A nurse in the emergency department obtains a blood sample
from an arm with an active IV infusion. The lab reports
unexpectedly low potassium compared with the clinical picture.
What is the most likely preanalytic explanation and the nurse’s
best next step?
A. Hemolysis from technique; request a repeat sample drawn
from the same arm after discarding the first tube.
B. Contamination/dilution from the IV fluid; stop the infusion,
obtain a new specimen from a different site, and note the IV on
the requisition.
C. True hypokalemia requiring immediate potassium
replacement.
D. Lab instrument calibration error; accept the result and treat
based on it.
, Correct answer
B
Rationales
• Correct (B): Specimen contamination or dilution by IV
fluids is a common preanalytic error causing spurious
electrolyte results; collecting from a different site after
stopping the infusion (or using distal venipuncture) is
appropriate.
• Incorrect (A): Hemolysis typically causes falsely elevated
potassium, not low values; moreover, redrawing from the
same arm while IV is present risks repeat contamination.
• Incorrect (C): Treating for true hypokalemia without
addressing possible specimen error risks inappropriate
therapy; correlation with clinical signs and repeat sampling
is needed.
• Incorrect (D): Calibration errors are less likely than
preanalytic contamination here; blindly treating based on a
potentially diluted sample is unsafe.
Teaching point
Avoid drawing blood proximal to IV infusions; stop infusion and
use a different site for accurate electrolytes.
Citation
Fischbach, F., Fischbach, M., & Stout, K. (2021). A Manual of
Laboratory and Diagnostic Tests (11th ed.). Ch. 1.
LABORATORY AND DIAGNOSTIC TESTS.
11TH EDITION
• AUTHOR(S)FRANCES FISCHBACH;
MARGARET FISCHBACH; KATE STOUT
TEST BANK
1
Reference
Ch. 1 — Diagnostic Testing
Stem
A 62-year-old man is scheduled for fasting glucose and lipid
studies this morning. He reports drinking coffee with cream 30
minutes ago and took his usual morning insulin. Which nursing
action best addresses preanalytic factors that could invalidate
the test results?
A. Proceed with specimen collection; note the coffee and insulin
on the lab requisition.
B. Delay specimen collection until the patient has been fasting
,for the required interval and notify provider about insulin
timing.
C. Collect the specimen immediately because coffee does not
alter glucose enough to matter.
D. Ask the patient to exercise for 10 minutes then collect the
specimen to reduce stress-related glucose changes.
Correct answer
B
Rationales
• Correct (B): Fasting requirements and recent insulin use
are preanalytic variables that significantly affect glucose
and lipid results. Delaying collection to achieve an
appropriate fasting interval (and informing the provider)
preserves result validity and patient safety.
• Incorrect (A): Simply documenting the preanalytic
violation does not correct the result; the sample may be
clinically misleading and should be deferred or repeated
per policy.
• Incorrect (C): Coffee with cream (carbohydrate/fat) and
recent insulin both can alter glucose and lipid values;
proceeding risks inaccurate interpretation.
• Incorrect (D): Exercise acutely alters glucose and other
metabolic parameters; it introduces another confounder
rather than resolving the fasting violation.
,Teaching point
Confirm and enforce test preparation (fasting, medication
timing) before specimen collection.
Citation
Fischbach, F., Fischbach, M., & Stout, K. (2021). A Manual of
Laboratory and Diagnostic Tests (11th ed.). Ch. 1.
2
Reference
Ch. 1 — Diagnostic Testing
Stem
A nurse in the emergency department obtains a blood sample
from an arm with an active IV infusion. The lab reports
unexpectedly low potassium compared with the clinical picture.
What is the most likely preanalytic explanation and the nurse’s
best next step?
A. Hemolysis from technique; request a repeat sample drawn
from the same arm after discarding the first tube.
B. Contamination/dilution from the IV fluid; stop the infusion,
obtain a new specimen from a different site, and note the IV on
the requisition.
C. True hypokalemia requiring immediate potassium
replacement.
D. Lab instrument calibration error; accept the result and treat
based on it.
, Correct answer
B
Rationales
• Correct (B): Specimen contamination or dilution by IV
fluids is a common preanalytic error causing spurious
electrolyte results; collecting from a different site after
stopping the infusion (or using distal venipuncture) is
appropriate.
• Incorrect (A): Hemolysis typically causes falsely elevated
potassium, not low values; moreover, redrawing from the
same arm while IV is present risks repeat contamination.
• Incorrect (C): Treating for true hypokalemia without
addressing possible specimen error risks inappropriate
therapy; correlation with clinical signs and repeat sampling
is needed.
• Incorrect (D): Calibration errors are less likely than
preanalytic contamination here; blindly treating based on a
potentially diluted sample is unsafe.
Teaching point
Avoid drawing blood proximal to IV infusions; stop infusion and
use a different site for accurate electrolytes.
Citation
Fischbach, F., Fischbach, M., & Stout, K. (2021). A Manual of
Laboratory and Diagnostic Tests (11th ed.). Ch. 1.
