TheoryCSMLS Medical Lab Exam Prep
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CSMLS Medical Lab Exam Prep sample questions
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Regs Which anticoagulant is found in the lavender-top (EDTA) evacuated blood collection tube?
A. Sodium citrate
B. Lithium heparin
C. EDTA (ethylenediaminetetraacetic acid) ✓
D. Sodium fluoride
Correct — C. Lavender-top tubes contain EDTA, which prevents clotting by chelating calcium ions. These tubes are the standard choice for complete blood counts (CBC) and hematology testing because EDTA preserves cell morphology well.
Ops What is the primary function of the mitochondria within a cell?
A. Protein synthesis
B. ATP (energy) production ✓
C. Lipid storage
D. DNA transcription
Correct — B. Mitochondria are known as the powerhouse of the cell because they generate ATP through oxidative phosphorylation and the citric acid cycle. They contain their own DNA and are essential for cellular respiration.
Safety In urinalysis, which reagent strip test detects the presence of nitrites indicating bacterial infection?
A. Leukocyte esterase
B. Nitrite test ✓
C. Protein test
D. Glucose oxidase test
Correct — B. The nitrite test on a urine dipstick detects nitrites produced when certain bacteria (especially Gram-negative organisms) convert urinary nitrates to nitrites. A positive nitrite test is a strong indicator of urinary tract infection.
Roles Which of the following blood components is responsible for the transport of carbon dioxide from tissues back to the lungs?
A. Plasma albumin
B. Hemoglobin in red blood cells ✓
C. Platelets
D. Fibrinogen
Correct — B. Hemoglobin in red blood cells transports the majority of carbon dioxide (CO2) from tissues to the lungs, primarily as carbaminohemoglobin. A smaller portion is dissolved in plasma or converted to bicarbonate ions by carbonic anhydrase.
Emergency Which of the following is the correct order of draw when using evacuated blood collection tubes?
A. Lavender, light blue, red, green
B. Light blue, red/SST, green, lavender ✓
C. Red, light blue, lavender, green
D. Green, lavender, red, light blue
Correct — B. The recommended order of draw is: blood cultures, light blue (citrate), red or SST (no additive or gel), green (heparin), lavender (EDTA), gray (fluoride). This order minimizes carryover of additives between tubes that could affect test results.
Regs The Westgard rules in laboratory quality control are primarily used to:
A. Calculate reference ranges for patient populations
B. Determine when a control run should be rejected due to error ✓
C. Select appropriate culture media for specimens
D. Calibrate laboratory instruments annually
Correct — B. Westgard rules are a set of statistical rules applied to quality control data to determine whether an analytical run should be accepted or rejected based on systematic or random error. They help laboratories identify when instruments are out of control before patient results are reported.
Ops When performing a venipuncture, which needle gauge is most commonly used for routine adult blood collection?
A. 18 gauge
B. 21 gauge ✓
C. 25 gauge
D. 30 gauge
Correct — B. A 21-gauge needle is the most commonly used for routine adult venipuncture as it provides adequate blood flow without causing excessive trauma to the vein. Smaller gauges (higher numbers) are used for fragile veins or pediatric patients.
Safety Which enzyme is elevated in acute myocardial infarction and is considered the most sensitive and specific cardiac biomarker?
A. Alkaline phosphatase (ALP)
B. Alanine aminotransferase (ALT)
C. Cardiac troponin I or T ✓
D. Lactate dehydrogenase (LDH)
Correct — C. Cardiac troponins (cTnI and cTnT) are the most sensitive and specific biomarkers for myocardial injury. They are released into the blood within 3-6 hours of myocardial infarction, peak at 12-24 hours, and remain elevated for 7-14 days.
About the CSMLS Medical Lab Exam Prep test
CSMLS Medical Lab Exam Prep candidates are tested on Nursing/Medical and Regs, in the same format the real exam uses. Every question here comes with a plain-language explanation, so you learn why an answer is right instead of memorising it — with 387 questions to start on.
You will be tested on
- Safe and effective care environment
- Health promotion and maintenance
- Psychosocial and physiological integrity
- Pharmacology, infection control and patient safety
How TheoryPractice helps you pass
- Real exam-style questions with instant, detailed explanations
- Full timed mock exams that mirror the real test format
- Flashcards & quiz modes from the same question bank
- Progress tracking so you know exactly when you're ready
Topics in this question bank
Safe and effective care environment
Health promotion and maintenance
Psychosocial and physiological integrity
Pharmacology, infection control and patient safety
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