NR 511 Differential Diagnosis & Primary Care Midterm Review 2026/2027

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NR 511 Differential Diagnosis and
Primary Care- Mid Term Review




QUESTION
What is the sensitivity of the Prostate Specific Antigen (PSA) for detecting prostate cancer?
# men with prostate cancer
# men with positive PSA
160
# men with negative PSA
40
total
200


Correct Answer:
160/200. Sensitivity is the proportion of patients with the disease that have a positive result; it
is the number of true positives divided by the total number of patients who have the disease.




pg. 1


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,NR 511 Differential Diagnosis and Primaryhttps://www.stuvia.com/user/gabrielucky
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QUESTION


A diagnostic test is used in a sample of 1000 patients. 500 of these patients have the disease,
while 500 do not. Of those 500 patients without the disease, 30 test positive, and 470 test
negative. What is the specificity of the test?


Correct Answer:
470/500.

Specificity is the proportion of patients who test negative out of the total number of patients
who do not have the disease; it is the number of true negatives overall negatives. In this
example, 500/1000 patients have the disease. Of those 500 patients without the disease, 30
test positive, and 470 test negative.



QUESTION
The Positive Predictive Value (PPV) of a test refers to which of the following?


Correct Answer:
The proportion of patients with a positive test who have the disease.




QUESTION
Which of the following depends on the prevalence of the disease?




Correct Answer:
Positive predictive value.

Predictive values depend on the prevalence of disease in the population whereas sensitivity and




pg. 2


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specificity are intrinsic properties of the test. Reliability refers to the consistency or stability of a
measure.




QUESTION
A low pretest probability of disease may lead to which of the following?




Correct Answer:
Low positive predictive value and more false-positive results.

Positive predictive value increases with prevalence; therefore, a low prevalence value yields a
low positive predictive value and implies a high false-positive rate. Negative predictive value
decreases with prevalence, and sensitivity and specificity do not vary with prevalence.




QUESTION
If you strongly suspect that a patient is positive for a specific condition but tests negative, the
negative result may be:


Correct Answer:
False-negative test results due to a low negative predictive value.

At the individual level, your clinical suspicion is equivalent to pre-test probability and high
prevalence at the population level. Negative predictive value is inversely correlated with
prevalence; therefore, your clinical suspicion translates to a low negative predictive value,
suggesting a false-negative test result.




QUESTION


pg. 3


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Which test(s) provide data relevant to the chief complaint: Fever


Correct Answer:
CBC
Check CBC with differential for neutrophil shift in suspected infection




QUESTION
Which test(s) provide data relevant to the chief complaint: Unexplained bruising


Correct Answer:
CBC
Check platelet count




QUESTION
Which test(s) provide data relevant to the chief complaint: Fatigue


Correct Answer:
Both CBC and CMP
Check RBC, Hgb and Hct for anemia, CMP for potential liver or kidney abnormalities




QUESTION
Which test(s) provide data relevant to the chief complaint: Cardiac dysrhythmias




pg. 4


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