AMT MLS Examination part II
Strategy Blueprint
AMT MLS Board Certification Comprehensive Success Examination
A comprehensive,350-question mock exam aligned with the American Medical
Technologists (AMT) Medical Laboratory Scientist (MLS) exam content outline.
This practice test integrates core laboratory topics—including Hematology,
Hemostasis, Urinalysis, Clinical Chemistry, Microbiology, Blood Bank, and
Quality Control—complete with answer keys and detailed explanations.
1. A clinical laboratory scientist observes small, refractile inclusions located near the
periphery of red blood cells on a Wright-stained peripheral smear. A supravital stain
(New Methylene Blue) confirms these inclusions as precipitated hemoglobin. What are
these inclusions?
A) Howell-Jolly bodies
B) Heinz bodies
C) Pappenheimer bodies
D) Basophilic stippling
Answer: B) Heinz bodies
Rationale: Heinz bodies are inclusions of denatured, precipitated hemoglobin attached
to the erythrocyte membrane, characteristically induced by oxidative stress (such as in
G6PD deficiency). They are not visible on a standard Wright stain (appearing only as
refractile areas or bite cells) but are clearly visualized using supravital stains like New
Methylene Blue or Crystal Violet.
2. A patient presenting with severe microcytic, hypochromic anemia displays an elevated
hemoglobin \(A_{2}\) level of 5.2% on hemoglobin electrophoresis. This finding is
diagnostic for:
A) Iron deficiency anemia
B) Beta-thalassemia minor
C) Sickle cell trait (Hb AS)
D) Alpha-thalassemia trait
Answer: B) Beta-thalassemia minor
Rationale: Normal adult hemoglobin \(A_{2}\) levels are less than 3.5%. In beta-
thalassemia minor, a decrease in beta-globin chain synthesis causes a compensatory
increase in delta-chain synthesis, leading to an elevated \(HbA_{2}\) fraction
(\(>3.5\%\)). Iron deficiency anemia is associated with normal or decreased \(HbA_{2}\)
levels.
,3. While performing a manual differential on a peripheral blood smear, the MLS notes that
nearly all neutrophils exhibit hyposegmented, bi-lobed nuclei shaped like dumbbells or
spectacles, while the chromatin is densely clumped. What is this benign genetic
variation?
A) Chédiak-Higashi anomaly
B) Pelger-Huët anomaly
C) May-Hegglin anomaly
D) Alder-Reilly anomaly
Answer: B) Pelger-Huët anomaly
Rationale: Pelger-Huët anomaly is an autosomal dominant benign condition
characterized by the failure of granulocyte nuclei to segment normally. The cells
function perfectly but mimic a left shift (increased bands). It can be distinguished from a
true left shift by the characteristic spectacle shape ("pince-nez") and heavy chromatin
clumping.
4. A patient’s automated complete blood count indicates a markedly low platelet count of
32,000/\(\mu \)L. Upon reviewing the peripheral blood smear collected in an EDTA tube,
the MLS notes massive platelet satellitism and clumping around neutrophils. What is the
next immediate action?
A) Report the critical low platelet count immediately to the physician
B) Request a new specimen collected in a sodium citrate (blue top) tube and re-run
C) Perform a manual platelet count on the original EDTA sample
D) Dilute the original sample 1:10 with sterile normal saline
Answer: B) Request a new specimen collected in a sodium citrate (blue top) tube
and re-run
Rationale: Platelet satellitism and clumping in an EDTA tube is an in vitro artifact
caused by EDTA-dependent autoantibodies that alter platelet surface membranes.
Drawing the blood into a sodium citrate tube eliminates this phenomenon. The platelet
count from the citrate tube must then be multiplied by 1.1 to correct for the liquid
anticoagulant dilution.
5. A coagulation profile reveals a prolonged Prothrombin Time (PT) and a normal activated
Partial Thromboplastin Time (aPTT). This combination indicates a functional deficiency
in which coagulation factor?
A) Factor VIII
B) Factor IX
C) Factor VII
D) Factor X
Answer: C) Factor VII
Rationale: The Prothrombin Time (PT) evaluates the extrinsic and common pathways of
the coagulation cascade. Factor VII is the unique diagnostic component of the extrinsic
pathway. A deficiency in Factor VII prolongs the PT while leaving the intrinsic-based
aPTT completely normal.
6. A patient on continuous intravenous unfractionated heparin therapy is monitored daily.
Which of the following tests is standard for monitoring this therapy?
A) Prothrombin Time (PT)
B) Activated partial thromboplastin time (aPTT)
, C) Bleeding time
D) Thrombin time alone
Answer: B) Activated partial thromboplastin time (aPTT)
Rationale: Unfractionated heparin enhances the activity of antithrombin III, which
primarily inactivates factors IIa (thrombin) and Xa in the intrinsic and common pathways.
The aPTT is highly sensitive to these shifts and serves as the standard tool for
monitoring therapeutic heparin titration.
7. Microscopic analysis of a patient's urine sediment reveals yellow-brown, spherical
crystals with long, irregular spicules, described as "thorny apples," in alkaline urine.
Identify these crystals:
A) Ammonium biurate
B) Calcium carbonate
C) Cholesterol
D) Tyrosine
Answer: A) Ammonium biurate
Rationale: Ammonium biurate crystals are yellow-brown spheres covered with sharp
spicules ("thorny apples"). They occur characteristically in old or poorly preserved urine
specimens that have transitioned to an alkaline pH due to bacterial ammonia
production.
8. A macroscopic urine examination reveals a dark, amber-colored specimen that
produces a thick, long-lasting yellow foam when shaken. This reaction indicates the
presence of:
A) Glucose
B) Protein alone
C) Bilirubin
D) Ketones
Answer: C) Bilirubin
Rationale: While significant proteinuria can cause a white, shifting foam when shaken,
the presence of conjugated bilirubin imparts a distinctive, vibrant yellow-amber color to
the foam due to the pigment's physical properties.
9. A routine chemical urinalysis yields a positive result on the blood pad, but microscopic
analysis of the sediment reveals zero red blood cells per high-power field. Which
condition explains this discrepancy?
A) Yeast contamination misidentified as RBCs
B) Intravascular hemolysis resulting in hemoglobinuria
C) Severe radiographic contrast media interference
D) High ascorbic acid concentration
Answer: B) Intravascular hemolysis resulting in hemoglobinuria
Rationale: The urine dipstick chemical pad detects the pseudoperoxidase activity of
hemoglobin, reacting to both intact RBCs (which lyse on the pad) and free hemoglobin.
If free hemoglobin is excreted (hemoglobinuria) or if RBCs lyse in dilute/alkaline urine,
the chemical test remains positive despite the absence of intact red cells under the
microscope.
, 10. A lumbar puncture is performed on a patient with suspected subarachnoid hemorrhage.
The fluid is collected sequentially into three tubes. If the intracranial bleeding is due to a
true in vivo subarachnoid hemorrhage rather than a traumatic tap, what will the MLS
observe?
A) Tube 1 is bloodier than Tube 3, and the supernatant is completely clear
B) All three tubes are equally bloody, and the supernatant is xanthochromic
C) Fluid clots solidly within 5 minutes of collection
D) The red cell count drops to zero in Tube 3
Answer: B) All three tubes are equally bloody, and the supernatant is
xanthochromic
Rationale: In a true subarachnoid hemorrhage, blood has been present in the CSF long
enough for RBCs to break down into bilirubin, making the centrifuged supernatant
yellowish (xanthochromic), and the blood is evenly distributed across all tubes. A
traumatic tap shows a progressive clearing of blood from Tube 1 to Tube 3 and a clear
supernatant.
11. A chemistry analyzer utilizing an enzymatic method for urea measurement measures
the decrease in absorbance at 340 nm as NADH is oxidized to NAD+. This reactions
utilizes which coupled enzyme?
A) Hexokinase
B) Urease and glutamate dehydrogenase
C) Uricase
D) Glycerol kinase
Answer: B) Urease and glutamate dehydrogenase
Rationale: In this standard methodology, urease hydrolyzes urea into ammonia and
ammonium carbonate. Glutamate dehydrogenase then uses this ammonia to convert
alpha-ketoglutarate to glutamate, consuming NADH in the process. The rate of
decrease in NADH absorbance is directly proportional to the urea concentration.
12. A patient's chemistry profile demonstrates a serum calcium level of 6.2 mg/dL. Before
calling this in as a critical value, the MLS should evaluate which other analyte to
calculate the corrected calcium?
A) Phosphorus
B) Albumin
C) Magnesium
D) Creatinine
Answer: B) Albumin
Rationale: Approximately 40–50% of circulating serum calcium is bound to plasma
proteins, primarily albumin. If a patient has severe hypoalbuminemia, the total
measured serum calcium will appear low even though the physiologically active ionized
calcium is normal. Formula: \(\text{Corrected Calcium} = \text{Measured Total Ca} + 0.8
\times (4.0 - \text{Patient Albumin})\).
13. A serum lipid panel returns a total cholesterol of 250 mg/dL, an HDL of 40 mg/dL, and
triglycerides of 150 mg/dL. Using the Friedewald equation, calculate the patient's LDL
cholesterol concentration:
A) 180 mg/dL
B) 210 mg/dL
Strategy Blueprint
AMT MLS Board Certification Comprehensive Success Examination
A comprehensive,350-question mock exam aligned with the American Medical
Technologists (AMT) Medical Laboratory Scientist (MLS) exam content outline.
This practice test integrates core laboratory topics—including Hematology,
Hemostasis, Urinalysis, Clinical Chemistry, Microbiology, Blood Bank, and
Quality Control—complete with answer keys and detailed explanations.
1. A clinical laboratory scientist observes small, refractile inclusions located near the
periphery of red blood cells on a Wright-stained peripheral smear. A supravital stain
(New Methylene Blue) confirms these inclusions as precipitated hemoglobin. What are
these inclusions?
A) Howell-Jolly bodies
B) Heinz bodies
C) Pappenheimer bodies
D) Basophilic stippling
Answer: B) Heinz bodies
Rationale: Heinz bodies are inclusions of denatured, precipitated hemoglobin attached
to the erythrocyte membrane, characteristically induced by oxidative stress (such as in
G6PD deficiency). They are not visible on a standard Wright stain (appearing only as
refractile areas or bite cells) but are clearly visualized using supravital stains like New
Methylene Blue or Crystal Violet.
2. A patient presenting with severe microcytic, hypochromic anemia displays an elevated
hemoglobin \(A_{2}\) level of 5.2% on hemoglobin electrophoresis. This finding is
diagnostic for:
A) Iron deficiency anemia
B) Beta-thalassemia minor
C) Sickle cell trait (Hb AS)
D) Alpha-thalassemia trait
Answer: B) Beta-thalassemia minor
Rationale: Normal adult hemoglobin \(A_{2}\) levels are less than 3.5%. In beta-
thalassemia minor, a decrease in beta-globin chain synthesis causes a compensatory
increase in delta-chain synthesis, leading to an elevated \(HbA_{2}\) fraction
(\(>3.5\%\)). Iron deficiency anemia is associated with normal or decreased \(HbA_{2}\)
levels.
,3. While performing a manual differential on a peripheral blood smear, the MLS notes that
nearly all neutrophils exhibit hyposegmented, bi-lobed nuclei shaped like dumbbells or
spectacles, while the chromatin is densely clumped. What is this benign genetic
variation?
A) Chédiak-Higashi anomaly
B) Pelger-Huët anomaly
C) May-Hegglin anomaly
D) Alder-Reilly anomaly
Answer: B) Pelger-Huët anomaly
Rationale: Pelger-Huët anomaly is an autosomal dominant benign condition
characterized by the failure of granulocyte nuclei to segment normally. The cells
function perfectly but mimic a left shift (increased bands). It can be distinguished from a
true left shift by the characteristic spectacle shape ("pince-nez") and heavy chromatin
clumping.
4. A patient’s automated complete blood count indicates a markedly low platelet count of
32,000/\(\mu \)L. Upon reviewing the peripheral blood smear collected in an EDTA tube,
the MLS notes massive platelet satellitism and clumping around neutrophils. What is the
next immediate action?
A) Report the critical low platelet count immediately to the physician
B) Request a new specimen collected in a sodium citrate (blue top) tube and re-run
C) Perform a manual platelet count on the original EDTA sample
D) Dilute the original sample 1:10 with sterile normal saline
Answer: B) Request a new specimen collected in a sodium citrate (blue top) tube
and re-run
Rationale: Platelet satellitism and clumping in an EDTA tube is an in vitro artifact
caused by EDTA-dependent autoantibodies that alter platelet surface membranes.
Drawing the blood into a sodium citrate tube eliminates this phenomenon. The platelet
count from the citrate tube must then be multiplied by 1.1 to correct for the liquid
anticoagulant dilution.
5. A coagulation profile reveals a prolonged Prothrombin Time (PT) and a normal activated
Partial Thromboplastin Time (aPTT). This combination indicates a functional deficiency
in which coagulation factor?
A) Factor VIII
B) Factor IX
C) Factor VII
D) Factor X
Answer: C) Factor VII
Rationale: The Prothrombin Time (PT) evaluates the extrinsic and common pathways of
the coagulation cascade. Factor VII is the unique diagnostic component of the extrinsic
pathway. A deficiency in Factor VII prolongs the PT while leaving the intrinsic-based
aPTT completely normal.
6. A patient on continuous intravenous unfractionated heparin therapy is monitored daily.
Which of the following tests is standard for monitoring this therapy?
A) Prothrombin Time (PT)
B) Activated partial thromboplastin time (aPTT)
, C) Bleeding time
D) Thrombin time alone
Answer: B) Activated partial thromboplastin time (aPTT)
Rationale: Unfractionated heparin enhances the activity of antithrombin III, which
primarily inactivates factors IIa (thrombin) and Xa in the intrinsic and common pathways.
The aPTT is highly sensitive to these shifts and serves as the standard tool for
monitoring therapeutic heparin titration.
7. Microscopic analysis of a patient's urine sediment reveals yellow-brown, spherical
crystals with long, irregular spicules, described as "thorny apples," in alkaline urine.
Identify these crystals:
A) Ammonium biurate
B) Calcium carbonate
C) Cholesterol
D) Tyrosine
Answer: A) Ammonium biurate
Rationale: Ammonium biurate crystals are yellow-brown spheres covered with sharp
spicules ("thorny apples"). They occur characteristically in old or poorly preserved urine
specimens that have transitioned to an alkaline pH due to bacterial ammonia
production.
8. A macroscopic urine examination reveals a dark, amber-colored specimen that
produces a thick, long-lasting yellow foam when shaken. This reaction indicates the
presence of:
A) Glucose
B) Protein alone
C) Bilirubin
D) Ketones
Answer: C) Bilirubin
Rationale: While significant proteinuria can cause a white, shifting foam when shaken,
the presence of conjugated bilirubin imparts a distinctive, vibrant yellow-amber color to
the foam due to the pigment's physical properties.
9. A routine chemical urinalysis yields a positive result on the blood pad, but microscopic
analysis of the sediment reveals zero red blood cells per high-power field. Which
condition explains this discrepancy?
A) Yeast contamination misidentified as RBCs
B) Intravascular hemolysis resulting in hemoglobinuria
C) Severe radiographic contrast media interference
D) High ascorbic acid concentration
Answer: B) Intravascular hemolysis resulting in hemoglobinuria
Rationale: The urine dipstick chemical pad detects the pseudoperoxidase activity of
hemoglobin, reacting to both intact RBCs (which lyse on the pad) and free hemoglobin.
If free hemoglobin is excreted (hemoglobinuria) or if RBCs lyse in dilute/alkaline urine,
the chemical test remains positive despite the absence of intact red cells under the
microscope.
, 10. A lumbar puncture is performed on a patient with suspected subarachnoid hemorrhage.
The fluid is collected sequentially into three tubes. If the intracranial bleeding is due to a
true in vivo subarachnoid hemorrhage rather than a traumatic tap, what will the MLS
observe?
A) Tube 1 is bloodier than Tube 3, and the supernatant is completely clear
B) All three tubes are equally bloody, and the supernatant is xanthochromic
C) Fluid clots solidly within 5 minutes of collection
D) The red cell count drops to zero in Tube 3
Answer: B) All three tubes are equally bloody, and the supernatant is
xanthochromic
Rationale: In a true subarachnoid hemorrhage, blood has been present in the CSF long
enough for RBCs to break down into bilirubin, making the centrifuged supernatant
yellowish (xanthochromic), and the blood is evenly distributed across all tubes. A
traumatic tap shows a progressive clearing of blood from Tube 1 to Tube 3 and a clear
supernatant.
11. A chemistry analyzer utilizing an enzymatic method for urea measurement measures
the decrease in absorbance at 340 nm as NADH is oxidized to NAD+. This reactions
utilizes which coupled enzyme?
A) Hexokinase
B) Urease and glutamate dehydrogenase
C) Uricase
D) Glycerol kinase
Answer: B) Urease and glutamate dehydrogenase
Rationale: In this standard methodology, urease hydrolyzes urea into ammonia and
ammonium carbonate. Glutamate dehydrogenase then uses this ammonia to convert
alpha-ketoglutarate to glutamate, consuming NADH in the process. The rate of
decrease in NADH absorbance is directly proportional to the urea concentration.
12. A patient's chemistry profile demonstrates a serum calcium level of 6.2 mg/dL. Before
calling this in as a critical value, the MLS should evaluate which other analyte to
calculate the corrected calcium?
A) Phosphorus
B) Albumin
C) Magnesium
D) Creatinine
Answer: B) Albumin
Rationale: Approximately 40–50% of circulating serum calcium is bound to plasma
proteins, primarily albumin. If a patient has severe hypoalbuminemia, the total
measured serum calcium will appear low even though the physiologically active ionized
calcium is normal. Formula: \(\text{Corrected Calcium} = \text{Measured Total Ca} + 0.8
\times (4.0 - \text{Patient Albumin})\).
13. A serum lipid panel returns a total cholesterol of 250 mg/dL, an HDL of 40 mg/dL, and
triglycerides of 150 mg/dL. Using the Friedewald equation, calculate the patient's LDL
cholesterol concentration:
A) 180 mg/dL
B) 210 mg/dL
