DHA Laboratory Medicine & Clinical Diagnostics

Question 1

A patient on warfarin therapy for atrial fibrillation has an INR of 5.8 with no active bleeding. What is the MOST appropriate initial management?

Accepted Answer

Hold warfarin and monitor; administer oral vitamin K 1–2.5 mg if needed

Answer

Administer intravenous vitamin K 10 mg immediately

Answer

Give fresh frozen plasma (FFP) urgently

Answer

Continue warfarin at the same dose and recheck in 1 week

Question 2

A patient's HbA1c is reported as 8.5%. According to standard diabetes management guidelines, what does this value indicate?

Accepted Answer

Average blood glucose of approximately 197 mg/dL over the past 2–3 months

Answer

Average blood glucose of approximately 126 mg/dL — at the diagnostic threshold

Answer

Average blood glucose of approximately 240 mg/dL over the past 2–3 months

Answer

Normal glycemic control — target achieved

Question 3

A patient presents 4 hours after chest pain onset. Troponin I is elevated at 2.8 ng/mL (upper reference limit 0.04 ng/mL). ECG shows ST elevation in V1–V4. The CORRECT interpretation is:

Accepted Answer

ST-elevation myocardial infarction (STEMI) — activate cath lab immediately

Answer

Elevated troponin confirms heart failure — start diuresis

Answer

Result is a false positive; troponin rises only after 12 hours

Answer

Unstable angina — admit for observation and serial ECGs only

Question 4

When collecting blood cultures from a patient with suspected bacteremia, which practice is MOST important to minimize contamination?

Accepted Answer

Disinfect the venipuncture site with chlorhexidine or alcohol and allow it to fully dry before puncture

Answer

Collect samples immediately after antibiotic administration

Answer

Use the same venipuncture site for all bottles to minimize patient discomfort

Answer

Collect only one set of blood cultures to reduce volume drawn

Question 5

A complete blood count (CBC) shows: WBC 1.8 × 10⁹/L, Hgb 7.2 g/dL, Platelets 45 × 10⁹/L. This pattern of pancytopenia MOST suggests which underlying condition?

Accepted Answer

Bone marrow failure or infiltration (e.g., aplastic anemia, leukemia)

Answer

Iron deficiency anemia

Answer

Polycythemia vera

Answer

Dehydration with hemoconcentration

Question 6

A urinalysis shows: specific gravity 1.030, pH 5.0, protein 2+, glucose 3+, nitrites positive, leukocyte esterase positive, RBC 10–15/hpf. Which combination of findings MOST strongly suggests urinary tract infection WITH underlying diabetes?

Accepted Answer

Glucose 3+ combined with nitrites positive and leukocyte esterase positive

Answer

Specific gravity 1.030 and pH 5.0

Answer

Protein 2+ and RBC 10–15/hpf

Answer

High specific gravity and low pH alone