PEBC Diagnostic Procedures 5

Question 1

A patient on lithium therapy has a serum lithium level of 1.8 mmol/L. The therapeutic range is 0.6–1.2 mmol/L. Which symptom is most consistent with lithium toxicity?

Accepted Answer

Coarse tremor, ataxia, and confusion

Answer

Serum lithium > 1.5 mmol/L indicates serious toxicity, manifesting as coarse tremor, ataxia, confusion, and in severe cases, seizures or coma.

Question 2

Which test is the gold standard for diagnosing pulmonary embolism?

Accepted Answer

CT pulmonary angiography (CTPA)

Answer

CT pulmonary angiography is the preferred and gold standard imaging modality for diagnosing pulmonary embolism due to its high sensitivity and specificity.

Question 3

A patient's stool culture is positive for Clostridioides difficile toxin. Which test characteristic makes the PCR assay preferred over enzyme immunoassay (EIA) for toxin detection?

Accepted Answer

Higher sensitivity for detecting toxin genes

Answer

PCR-based testing detects the toxin gene with higher sensitivity than EIA toxin detection, reducing the rate of false-negative results in C. difficile infection diagnosis.

Question 4

A pharmacist is counselling a patient about their INR result of 1.1 while on warfarin for atrial fibrillation (target INR 2.0–3.0). Which is the most likely cause of a subtherapeutic INR?

Accepted Answer

Increased dietary vitamin K intake

Answer

Vitamin K competes with warfarin's mechanism, and a high dietary intake of vitamin K–rich foods reduces warfarin's anticoagulant effect, leading to a subtherapeutic INR.

Question 5

A patient is referred for a bone mineral density (BMD) test. Their T-score at the femoral neck is −2.6. How should the pharmacist interpret this result?

Accepted Answer

Osteoporosis

Answer

A T-score of −2.5 or lower is diagnostic of osteoporosis per WHO criteria; a T-score of −2.6 meets this threshold.

PEBC - Pharmacy Examining Board of Canada Practice Test

PEBC - Pharmacy Examining Board of Canada Practice Test

PEBC Diagnostic Procedures 5