MLS ASCP EXAM RECALL QUESTIONS 2025 UPDATE| COMPREHENSIVE QUESTIONS AND
VERIFIED ANSWERS (COMPLETE SOLUTIONS) ASSURED SUCCESS|GRADE A+!! (100%
ACCURATE) GET IT RIGHT!!
Question 1
When monitoring a patient on Procainamide therapy, which of its metabolites must also be
measured to ensure therapeutic efficacy and safety?
A) Digoxin
B) N-acetylprocainamide (NAPA)
C) Theophylline
D) Phenobarbital
E) Quinidine
Correct Answer: B) N-acetylprocainamide (NAPA)
Rationale: Procainamide is metabolized by the liver into N-acetylprocainamide (NAPA).
Both the parent drug and the metabolite have anti-arrhythmic activity and potential
toxicity; therefore, both levels must be measured and added together to evaluate the
patient's clinical status.
Question 2
A fungal culture shows loose clusters of small spherical microconidia and a positive urease test.
Which organism is most likely?
A) Trichophyton rubrum
B) Microsporum canis
C) Trichophyton mentagrophytes
D) Epidermophyton floccosum
E) Candida albicans
Correct Answer: C) Trichophyton mentagrophytes
Rationale: Trichophyton mentagrophytes is characterized by grape-like clusters of
microconidia and is urease positive. This distinguishes it from T. rubrum, which typically
has tear-shaped microconidia and is urease negative.
Question 3
Beta-human chorionic gonadotropin (BHCG) is most commonly used as a tumor marker for
which of the following conditions?
A) Colon cancer
B) Prostatic adenocarcinoma
C) Choriocarcinoma
D) Hepatocellular carcinoma
E) Small cell lung cancer
Correct Answer: C) Choriocarcinoma
Rationale: While BHCG is the primary hormone of pregnancy, in oncology it serves as a
, 2
highly sensitive marker for germ cell tumors, specifically choriocarcinoma and certain
testicular cancers.
Question 4
Elevated levels of 5-Hydroxyindoleacetic acid (5-HIAA) in a 24-hour urine collection are
diagnostic for:
A) Pheochromocytoma
B) Neuroblastoma
C) Carcinoid tumors
D) Multiple myeloma
E) Renal cell carcinoma
Correct Answer: C) Carcinoid tumors
Rationale: 5-HIAA is the primary metabolite of serotonin. Carcinoid tumors, particularly
those arising in the small intestine, secrete large amounts of serotonin, leading to high levels
of 5-HIAA in the urine.
Question 5
Which biochemical test is most useful for differentiating Proteus vulgaris from Proteus
mirabilis?
A) Urease
B) Motility
C) Phenylalanine deaminase
D) Indole
E) H2S production
Correct Answer: D) Indole
Rationale: Both species are PDA and Urease positive and produce H2S. However, Proteus
vulgaris is indole positive, while Proteus mirabilis is indole negative.
Question 6
In blood bank, which substance can be used to neutralize Anti-P1 antibodies in a patient's serum?
A) Neutral saline
B) Hydatid cyst fluid
C) Human milk
D) Pigeon egg white
E) Both B and D
Correct Answer: E) Both B and D
Rationale: Anti-P1 is a common cold-reacting antibody. Hydatid cyst fluid (from
Echinococcus) and pigeon droppings/egg whites contain P1-like substances that can
neutralize the antibody, allowing for the detection of underlying alloantibodies.
, 3
Question 7
A patient is admitted with a suspected antacid overdose. Which of the following is the most
important laboratory parameter to check first?
A) Serum Sodium
B) Blood pH
C) Hemoglobin
D) Prothrombin Time
E) Bilirubin
Correct Answer: B) Blood pH
Rationale: Overdose of alkaline antacids can lead to metabolic alkalosis. Monitoring the
blood pH and bicarbonate levels is critical to assess the severity of the acid-base imbalance.
Question 8
A sample collected from a central venous catheter shows a significantly prolonged PT, PTT, and
Thrombin Time. What is the most likely cause?
A) Disseminated intravascular coagulation (DIC)
B) Vitamin K deficiency
C) Heparin contamination
D) Factor VII deficiency
E) Severe liver disease
Correct Answer: C) Heparin contamination
Rationale: Heparin is often used to "flush" or "lock" catheters. If the line is not properly
cleared before drawing blood for coagulation tests, heparin contamination will occur,
causing all clot-based tests to be prolonged, particularly the PTT and Thrombin Time.
Question 9
A mixing study is performed on a patient with a prolonged PTT. The PTT does not correct upon
mixing with normal pooled plasma. Which test should be performed next to investigate a
possible Lupus Anticoagulant?
A) PT
B) DRVVT (Dilute Russell Viper Venom Test)
C) Factor VIII assay
D) Fibrinogen
E) Bleeding Time
Correct Answer: B) DRVVT (Dilute Russell Viper Venom Test)
Rationale: Failure to correct in a mixing study suggests the presence of an inhibitor. The
DRVVT is a specific test for Lupus Anticoagulant (LA). It activates factor X directly; if LA
is present, it interferes with the phospholipid-dependent step, prolonging the time.
Question 10
Duplicate PT and PTT runs show normal PTs but consistently prolonged PTTs. Which of the
, 4
following should the technician check first?
A) The patient's hematocrit
B) The integrity of the CaCl2/phospholipid reagent delivery
C) The temperature of the incubator
D) The patient's platelet count
E) The concentration of sodium citrate
Correct Answer: B) The integrity of the CaCl2/phospholipid reagent delivery
Rationale: Since the PT (which uses different reagents) is normal, the issue is specific to the
PTT. Improper delivery of the PTT-specific activator or the calcium chloride/phospholipid
reagent will cause consistent prolongation across different patients.
Question 11
A patient is on Coumadin (warfarin) therapy. Which of the following vitamin K-dependent
factors/proteins will decrease first?
A) Factor II
B) Factor IX
C) Factor X
D) Protein C
E) Factor VII
Correct Answer: D) Protein C
Rationale: Warfarin inhibits the carboxylation of factors II, VII, IX, X and proteins C and
S. Protein C and Factor VII have the shortest half-lives (about 6 hours), meaning they
decrease the fastest when therapy begins.
Question 12
A peripheral blood smear shows a high number of stomatocytes. This morphology is most
frequently associated with which condition?
A) Iron deficiency anemia
B) Uremia
C) Liver disease (or hereditary stomatocytosis)
D) G6PD deficiency
E) Splenectomy
Correct Answer: C) Liver disease
Rationale: Stomatocytes (mouth cells) occur due to changes in the RBC membrane
permeability or lipid composition, often seen in chronic liver disease, alcoholism, or
hereditary conditions.
Question 13
Which of the following conditions is most closely associated with the presence of Burr cells
(Echinocytes) on a smear?
A) Sickle cell anemia
VERIFIED ANSWERS (COMPLETE SOLUTIONS) ASSURED SUCCESS|GRADE A+!! (100%
ACCURATE) GET IT RIGHT!!
Question 1
When monitoring a patient on Procainamide therapy, which of its metabolites must also be
measured to ensure therapeutic efficacy and safety?
A) Digoxin
B) N-acetylprocainamide (NAPA)
C) Theophylline
D) Phenobarbital
E) Quinidine
Correct Answer: B) N-acetylprocainamide (NAPA)
Rationale: Procainamide is metabolized by the liver into N-acetylprocainamide (NAPA).
Both the parent drug and the metabolite have anti-arrhythmic activity and potential
toxicity; therefore, both levels must be measured and added together to evaluate the
patient's clinical status.
Question 2
A fungal culture shows loose clusters of small spherical microconidia and a positive urease test.
Which organism is most likely?
A) Trichophyton rubrum
B) Microsporum canis
C) Trichophyton mentagrophytes
D) Epidermophyton floccosum
E) Candida albicans
Correct Answer: C) Trichophyton mentagrophytes
Rationale: Trichophyton mentagrophytes is characterized by grape-like clusters of
microconidia and is urease positive. This distinguishes it from T. rubrum, which typically
has tear-shaped microconidia and is urease negative.
Question 3
Beta-human chorionic gonadotropin (BHCG) is most commonly used as a tumor marker for
which of the following conditions?
A) Colon cancer
B) Prostatic adenocarcinoma
C) Choriocarcinoma
D) Hepatocellular carcinoma
E) Small cell lung cancer
Correct Answer: C) Choriocarcinoma
Rationale: While BHCG is the primary hormone of pregnancy, in oncology it serves as a
, 2
highly sensitive marker for germ cell tumors, specifically choriocarcinoma and certain
testicular cancers.
Question 4
Elevated levels of 5-Hydroxyindoleacetic acid (5-HIAA) in a 24-hour urine collection are
diagnostic for:
A) Pheochromocytoma
B) Neuroblastoma
C) Carcinoid tumors
D) Multiple myeloma
E) Renal cell carcinoma
Correct Answer: C) Carcinoid tumors
Rationale: 5-HIAA is the primary metabolite of serotonin. Carcinoid tumors, particularly
those arising in the small intestine, secrete large amounts of serotonin, leading to high levels
of 5-HIAA in the urine.
Question 5
Which biochemical test is most useful for differentiating Proteus vulgaris from Proteus
mirabilis?
A) Urease
B) Motility
C) Phenylalanine deaminase
D) Indole
E) H2S production
Correct Answer: D) Indole
Rationale: Both species are PDA and Urease positive and produce H2S. However, Proteus
vulgaris is indole positive, while Proteus mirabilis is indole negative.
Question 6
In blood bank, which substance can be used to neutralize Anti-P1 antibodies in a patient's serum?
A) Neutral saline
B) Hydatid cyst fluid
C) Human milk
D) Pigeon egg white
E) Both B and D
Correct Answer: E) Both B and D
Rationale: Anti-P1 is a common cold-reacting antibody. Hydatid cyst fluid (from
Echinococcus) and pigeon droppings/egg whites contain P1-like substances that can
neutralize the antibody, allowing for the detection of underlying alloantibodies.
, 3
Question 7
A patient is admitted with a suspected antacid overdose. Which of the following is the most
important laboratory parameter to check first?
A) Serum Sodium
B) Blood pH
C) Hemoglobin
D) Prothrombin Time
E) Bilirubin
Correct Answer: B) Blood pH
Rationale: Overdose of alkaline antacids can lead to metabolic alkalosis. Monitoring the
blood pH and bicarbonate levels is critical to assess the severity of the acid-base imbalance.
Question 8
A sample collected from a central venous catheter shows a significantly prolonged PT, PTT, and
Thrombin Time. What is the most likely cause?
A) Disseminated intravascular coagulation (DIC)
B) Vitamin K deficiency
C) Heparin contamination
D) Factor VII deficiency
E) Severe liver disease
Correct Answer: C) Heparin contamination
Rationale: Heparin is often used to "flush" or "lock" catheters. If the line is not properly
cleared before drawing blood for coagulation tests, heparin contamination will occur,
causing all clot-based tests to be prolonged, particularly the PTT and Thrombin Time.
Question 9
A mixing study is performed on a patient with a prolonged PTT. The PTT does not correct upon
mixing with normal pooled plasma. Which test should be performed next to investigate a
possible Lupus Anticoagulant?
A) PT
B) DRVVT (Dilute Russell Viper Venom Test)
C) Factor VIII assay
D) Fibrinogen
E) Bleeding Time
Correct Answer: B) DRVVT (Dilute Russell Viper Venom Test)
Rationale: Failure to correct in a mixing study suggests the presence of an inhibitor. The
DRVVT is a specific test for Lupus Anticoagulant (LA). It activates factor X directly; if LA
is present, it interferes with the phospholipid-dependent step, prolonging the time.
Question 10
Duplicate PT and PTT runs show normal PTs but consistently prolonged PTTs. Which of the
, 4
following should the technician check first?
A) The patient's hematocrit
B) The integrity of the CaCl2/phospholipid reagent delivery
C) The temperature of the incubator
D) The patient's platelet count
E) The concentration of sodium citrate
Correct Answer: B) The integrity of the CaCl2/phospholipid reagent delivery
Rationale: Since the PT (which uses different reagents) is normal, the issue is specific to the
PTT. Improper delivery of the PTT-specific activator or the calcium chloride/phospholipid
reagent will cause consistent prolongation across different patients.
Question 11
A patient is on Coumadin (warfarin) therapy. Which of the following vitamin K-dependent
factors/proteins will decrease first?
A) Factor II
B) Factor IX
C) Factor X
D) Protein C
E) Factor VII
Correct Answer: D) Protein C
Rationale: Warfarin inhibits the carboxylation of factors II, VII, IX, X and proteins C and
S. Protein C and Factor VII have the shortest half-lives (about 6 hours), meaning they
decrease the fastest when therapy begins.
Question 12
A peripheral blood smear shows a high number of stomatocytes. This morphology is most
frequently associated with which condition?
A) Iron deficiency anemia
B) Uremia
C) Liver disease (or hereditary stomatocytosis)
D) G6PD deficiency
E) Splenectomy
Correct Answer: C) Liver disease
Rationale: Stomatocytes (mouth cells) occur due to changes in the RBC membrane
permeability or lipid composition, often seen in chronic liver disease, alcoholism, or
hereditary conditions.
Question 13
Which of the following conditions is most closely associated with the presence of Burr cells
(Echinocytes) on a smear?
A) Sickle cell anemia
