10 free, exam-style Medical Laboratory Scientist (MLS) practice questions with answers and explanations. No signup required. Work through them below, then take the full free MLS practice test to study every exam domain.
A 55-year-old patient has a WBC of 185,000/μL with the differential showing all stages of granulocyte maturation (myeloblasts through segmented neutrophils), basophilia, and a low LAP (leukocyte alkaline phosphatase) score. This is MOST consistent with:
Correct answer: B - Chronic myelogenous leukemia (CML)
A patient presents with jaundice. Lab results show: total bilirubin 12 mg/dL, direct bilirubin 10 mg/dL, ALP markedly elevated, GGT elevated, ALT mildly elevated. These findings are MOST consistent with:
Correct answer: C - Obstructive jaundice
A patient has: Prolonged PT, prolonged APTT, low fibrinogen (55 mg/dL), elevated D-dimer, low platelets (35,000), and schistocytes on smear. This is MOST consistent with:
Correct answer: C - Disseminated intravascular coagulation (DIC)
A CSF Gram stain from a neonate shows gram-positive short rods. The organism grows on blood agar with beta-hemolysis and is catalase-positive, motile at 25°C, and bile esculin-positive. The MOST likely identification is:
Correct answer: B - Listeria monocytogenes
A patient develops fever, hypotension, back pain, and hemoglobinuria 15 minutes into a transfusion of packed RBCs. The MOST likely diagnosis is:
Correct answer: B - Acute hemolytic transfusion reaction
A patient's hepatitis panel shows: HBsAg positive, Anti-HBs negative, Anti-HBc IgM positive, Anti-HBc total positive, HBeAg positive. This is MOST consistent with:
Correct answer: B - Acute HBV infection
A patient in the ICU has the following results: BUN 85 mg/dL, Creatinine 8.5 mg/dL, Potassium 6.2 mEq/L, Phosphorus 7.8 mg/dL, Calcium 7.0 mg/dL. These results are MOST consistent with:
Correct answer: B - Acute or chronic renal failure
A stool specimen from a child with bloody diarrhea is cultured on SMAC agar. Colorless (non-sorbitol-fermenting) colonies are isolated. The organism is indole-positive and produces Shiga toxin. The MOST likely identification is:
Correct answer: B - E. coli O157:H7
A transfusion reaction workup reveals: the post-transfusion DAT is positive, the pre-transfusion DAT was negative, the visual hemolysis check is positive (pink serum), and ABO recheck of both patient and unit shows no discrepancy. An eluate from the patient's post-transfusion RBCs shows anti-Jka. The MOST likely event is:
Correct answer: B - Delayed hemolytic transfusion reaction due to anti-Jka
A CSF sample from a patient with suspected bacterial meningitis shows: WBC 2,500/μL (predominantly neutrophils), protein 250 mg/dL, glucose 20 mg/dL (serum glucose 100 mg/dL). This profile is MOST consistent with:
Correct answer: B - Bacterial meningitis
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