Medical Laboratory Technician Exam Medical Laboratory Technician MCQ 1 — Questions and Answers
Question 1: Which tube color is used for coagulation studies such as PT and aPTT?
- Green-top (lithium heparin)
- Light blue-top (sodium citrate) (Correct answer)
- Red-top (no additive)
- Yellow-top (SPS)
Correct answer: Light blue-top (sodium citrate)
Light blue-top tubes contain sodium citrate, a calcium-chelating anticoagulant that preserves clotting factors for coagulation testing. The 9:1 blood-to-anticoagulant ratio is critical for accurate results.
Question 2: A urine dipstick shows a positive nitrite result. This finding most likely indicates the presence of:
- Renal calculi
- Gram-positive cocci
- Gram-negative bacteria (Correct answer)
- Fungal infection
Correct answer: Gram-negative bacteria
Many gram-negative bacteria (e.g., E. coli) convert dietary nitrates to nitrites via reductase enzymes. A positive nitrite result strongly suggests a urinary tract infection caused by gram-negative organisms.
Question 3: Which of the following white blood cell types is the FIRST to respond to an acute bacterial infection?
- Lymphocytes
- Monocytes
- Eosinophils
- Neutrophils (Correct answer)
Correct answer: Neutrophils
Neutrophils are the primary first-responders in acute bacterial infections. They are phagocytic cells that rapidly migrate to sites of infection, and a left shift (increase in band neutrophils) is a classic laboratory finding.
Question 4: A blood specimen with a hemoglobin of 7.0 g/dL and a mean corpuscular volume (MCV) of 115 fL is most consistent with which type of anemia?
- Iron deficiency anemia
- Anemia of chronic disease
- Megaloblastic anemia (Correct answer)
- Sickle cell anemia
Correct answer: Megaloblastic anemia
Megaloblastic anemia is characterized by a markedly elevated MCV (macrocytosis, typically >100 fL) due to impaired DNA synthesis from vitamin B12 or folate deficiency, resulting in abnormally large red blood cells.
Question 5: Which quality control rule is violated when two consecutive control values fall more than 2 standard deviations on the same side of the mean?
- Westgard 1-3s rule
- Westgard 2-2s rule (Correct answer)
- Westgard R-4s rule
- Westgard 1-2s warning rule
Correct answer: Westgard 2-2s rule
The Westgard 2-2s rule is a rejection rule triggered when two consecutive control measurements exceed 2 SD on the same side of the mean, suggesting a systematic error or bias in the analytical run.
Question 6: A Gram stain of a sputum specimen reveals purple (violet) cocci in clusters. Which organism is most likely responsible?
- Streptococcus pneumoniae
- Escherichia coli
- Staphylococcus aureus (Correct answer)
- Neisseria meningitidis
Correct answer: Staphylococcus aureus
Staphylococcus aureus is a gram-positive coccus that characteristically arranges in grape-like clusters. It retains the crystal violet dye in the Gram stain process, appearing purple, distinguishing it from gram-negative organisms.
Medical Laboratory Technician Exam Medical Laboratory Technician MCQ 1
Which tube color is used for coagulation studies such as PT and aPTT?