AOA Clinical Diagnosis and Laboratory Medicine 3

Question 1

A positive tuberculin skin test (TST) with induration ≥ 5 mm is considered positive in which patient group?

Accepted Answer

HIV-positive patients

Answer

Healthcare workers with no known exposure

Answer

Individuals from low-prevalence countries

Answer

Patients older than 65

Question 2

Which diagnostic criterion confirms polycythemia vera according to WHO guidelines?

Accepted Answer

JAK2 V617F mutation with elevated hemoglobin and low EPO

Answer

Elevated serum EPO with high hemoglobin

Answer

Elevated RBC mass with normal bone marrow

Answer

High hematocrit with elevated iron stores

Question 3

Which set of laboratory values best characterizes acute pancreatitis?

Accepted Answer

Elevated lipase >3× ULN, elevated amylase, normal LFTs

Answer

Elevated lipase >3× ULN, elevated bilirubin, normal amylase

Answer

Elevated amylase only with normal lipase

Answer

Normal lipase with elevated GGT and AST

Question 4

A patient with community-acquired pneumonia has a positive urinary antigen test. Which pathogen does this test most reliably detect?

Accepted Answer

Legionella pneumophila serogroup 1

Answer

Streptococcus pneumoniae

Answer

Mycoplasma pneumoniae

Answer

Haemophilus influenzae

Question 5

In a patient with suspected systemic lupus erythematosus (SLE), which antibody is most specific for the diagnosis?

Accepted Answer

Anti-double-stranded DNA (anti-dsDNA)

Answer

ANA (antinuclear antibody)

Answer

Anti-histone antibody

Answer

Rheumatoid factor

Question 6

Which HbA1c value establishes a diagnosis of diabetes mellitus according to ADA criteria?

Accepted Answer

HbA1c ≥ 6.5%

Answer

HbA1c ≥ 5.7%

Answer

HbA1c ≥ 6.0%

Answer

HbA1c ≥ 7.0%

Question 7

A 68-year-old man has a serum PSA of 8.2 ng/mL. Which factor would most increase the suspicion for prostate cancer over benign prostatic hyperplasia (BPH)?

Accepted Answer

Free PSA fraction of 8%

Answer

PSA velocity of 0.5 ng/mL/year

Answer

Symmetric prostate enlargement on DRE

Answer

Age-adjusted PSA within normal range