ABPath - American Board of Pathology Chemical Pathology Questions and Answers

Question 1

A 55-year-old male presents to the emergency department with severe headache, palpitations, and sweating.
His blood pressure is 210/120 mmHg.
A 24-hour urine collection is ordered to screen for a suspected pheochromocytoma.
Which of the following analytes provides the highest diagnostic sensitivity for this condition?

Accepted Answer

Fractionated metanephrines

Answer

Vanillylmandelic acid (VMA)

Answer

Total catecholamines

Answer

Homovanillic acid (HVA)

Question 2

A 68-year-old female is admitted with chest pain. Serial high-sensitivity cardiac troponin I (hs-cTnI) levels are measured. The first result is 45 ng/L (99th percentile URL: 26 ng/L). A second result 3 hours later is 250 ng/L. According to the universal definition of myocardial infarction, what does this pattern represent?

Accepted Answer

A significant rise and fall pattern indicative of acute myocardial infarction

Answer

Chronic myocardial injury

Answer

Analytic interference in the assay

Answer

A clinically insignificant fluctuation

Question 3

A patient with uncontrolled Type 1 diabetes presents with nausea, vomiting, and altered mental status. Laboratory results are: Na+ 132 mmol/L, K+ 5.1 mmol/L, Cl- 95 mmol/L, HCO3- 10 mmol/L, Glucose 550 mg/dL. What is the calculated serum anion gap, and what is its significance?

Accepted Answer

27 mmol/L, indicating a high anion gap metabolic acidosis

Answer

12 mmol/L, which is a normal anion gap

Answer

5 mmol/L, indicating a low anion gap

Answer

17 mmol/L, which is borderline high and requires further investigation

Question 4

Which of the following laboratory findings is most consistent with hypercalcemia of malignancy?

Accepted Answer

Elevated serum calcium, low PTH, elevated PTHrP

Answer

Elevated serum calcium, elevated PTH

Answer

Low serum calcium, elevated PTH

Answer

Elevated serum calcium, low PTH, low PTHrP

Question 5

A 45-year-old patient on long-term phenytoin therapy for a seizure disorder is admitted for pneumonia and found to have a serum albumin of 2.5 g/dL (normal 3.5-5.0 g/dL). The measured total phenytoin level is 15 mcg/mL (therapeutic range 10-20 mcg/mL). Which of the following is the most appropriate interpretation and action?

Accepted Answer

The patient is at risk for toxicity; the free phenytoin level should be checked or the dose should be reduced.

Answer

The level is therapeutic; no action is needed.

Answer

The patient is likely subtherapeutic due to low albumin; the dose should be increased.

Answer

The phenytoin level is invalid and should be redrawn.

Question 6

A comatose patient is brought to the emergency room with suspected toxic ingestion. Labs show: measured osmolality 350 mOsm/kg, Na+ 140 mmol/L, BUN 28 mg/dL, Glucose 90 mg/dL. The calculated osmolality is 295 mOsm/kg. Anion gap is 25 mEq/L. What is the most likely cause of the elevated osmolal gap and anion gap?

Accepted Answer

Ethylene glycol poisoning

Answer

Isopropanol ingestion

Answer

Ethanol intoxication

Answer

Diabetic ketoacidosis