Medical Laboratory Technologists Registration Assessment (Hong Kong)

Which of the following describes the chemical basis of the classic Jaffe reaction for measuring creatinine, and what is a common positive interferent?

• AReaction with copper sulfate in alkaline solution; interfered with by lipids
• BReaction with picric acid in alkaline solution; interfered with by acetoacetate
• CEnzymatic oxidation by creatinine amidohydrolase; interfered with by uric acid
• DReaction with sodium nitroprusside in acid solution; interfered with by glucose

A patient's arterial blood gas (ABG) results are as follows: pH = 7.25, pCO2 = 60 mmHg, HCO3- = 26 mEq/L. Which of the following is the correct acid-base classification?

• AUncompensated metabolic acidosis
• BFully compensated respiratory acidosis
• CUncompensated (or acute) respiratory acidosis
• DPartially compensated metabolic alkalosis

Which of the following conditions is most likely to produce a falsely decreased Hemoglobin A1c (HbA1c) level when measured by ion-exchange chromatography?

• AIron deficiency anemia
• BSplenectomy
• CPresence of Hemoglobin S or Hemoglobin C
• DChronic renal failure with erythropoietin therapy

Why is the hexokinase method considered the reference method for glucose determination over the glucose oxidase method?

• AHexokinase is highly specific for beta-D-glucose and requires no mutarotase enzyme
• BThe hexokinase coupled reaction is not affected by common reducing substances like uric a…
• CHexokinase directly produces a colored compound without requiring a secondary coupled enz…
• DHexokinase reagents are much cheaper and have a longer shelf life

Under which of the following circumstances is the Friedewald equation for calculating LDL cholesterol invalid?

• AWhen the patient's HDL cholesterol is less than 35 mg/dL
• BWhen the total cholesterol level exceeds 300 mg/dL
• CWhen the triglyceride level is greater than 400 mg/dL (or 4.52 mmol/L)
• DWhen the patient is on active statin therapy

Which of the following best explains how severe hyperproteinemia or hyperlipidemia causes pseudohyponatremia in laboratory measurements?

• AProteins and lipids bind sodium ions, preventing them from interacting with the electrode…
• BIndirect ion-selective electrodes (ISE) dilute the sample, underestimating sodium concent…
• CDirect ion-selective electrodes (ISE) are calibrated incorrectly for high-density solutio…
• DProteins alter the temperature coefficient of the measuring chamber, lowering the apparen…

In the Jendrassik-Grof method for bilirubin determination, what is the purpose of adding caffeine-benzoate reagent?

• ATo oxidize bilirubin to biliverdin for green spectrophotometric reading
• BTo solubilize and release unconjugated bilirubin from albumin, allowing it to react with…
• CTo destroy hemoglobin interference which acts as a positive chromogen
• DTo act as a pH buffer, shifting the reaction to an alkaline endpoint

Which of the following cardiac markers is the first to rise following an acute myocardial infarction (AMI), and which provides the longest diagnostic window?

• ACK-MB rises first; Troponin T provides the longest window
• BMyoglobin rises first; Troponin T/I provides the longest window
• CTroponin I rises first; Myoglobin provides the longest window
• DLDH rises first; CK-MB provides the longest window

A patient presents with a significantly elevated Alkaline Phosphatase (ALP). To differentiate whether the origin of this elevation is hepatobiliary or bone disease, which secondary enzyme test is most clinical useful?

• AAlanine aminotransferase (ALT)
• BGamma-glutamyltransferase (GGT)
• CAmylase
• DLactate dehydrogenase (LDH)

A 24-hour urine collection has a volume of 1440 mL. Urine creatinine is 100 mg/dL, and serum creatinine is 1.0 mg/dL. What is the calculated creatinine clearance (uncorrected for body surface area)?

• A10 mL/min
• B100 mL/min
• C144 mL/min
• D1000 mL/min

Which of the following laboratory results is characteristic of subclinical hypothyroidism?

• ADecreased TSH, elevated free T4
• BElevated TSH, normal free T4
• CNormal TSH, decreased free T4
• DElevated TSH, decreased free T4

For therapeutic drug monitoring of aminoglycoside antibiotics (e.g., gentamicin), when should the trough specimen be drawn?

• AExactly 30 minutes after completion of the intravenous infusion
• BImmediately before the administration of the next dose
• CMidway through the dosing interval
• DTwo hours after oral administration of the medication

Serum protein electrophoresis on agarose gel shows an intense, narrow band in the gamma-globulin region (M-spike). Which of the following is the most likely diagnosis?

• AAcute inflammation
• BAlpha-1 antitrypsin deficiency
• CMultiple myeloma
• DHepatic cirrhosis (beta-gamma bridging)

Which of the following cerebrospinal fluid (CSF) chemical patterns is most consistent with acute bacterial meningitis?

• AElevated protein, normal glucose, normal lactate
• BMarkedly elevated protein, markedly decreased glucose, elevated lactate
• CNormal protein, markedly decreased glucose, normal lactate
• DDecreased protein, elevated glucose, decreased lactate

Which tumor marker is clinically utilized for screening and monitoring of hepatocellular carcinoma (HCC) and germ cell tumors?

• ACarcinoembryonic Antigen (CEA)
• BAlpha-Fetoprotein (AFP)
• CProstate-Specific Antigen (PSA)
• DCancer Antigen 125 (CA-125)

Which of the following compounds accumulates in the urine of patients with acute intermittent porphyria (AIP) during an attack and can be detected using the Watson-Schwartz test?

• AProtoporphyrin IX
• BPorphobilinogen (PBG)
• CUroporphyrinogen III
• DDelta-aminolevulinic acid (ALA) only

Which iron panel profile is most characteristic of Anemia of Chronic Disease (ACD) / Anemia of Inflammation?

• ALow serum iron, high Total Iron Binding Capacity (TIBC), low ferritin
• BLow serum iron, low Total Iron Binding Capacity (TIBC), normal to high ferritin
• CHigh serum iron, low Total Iron Binding Capacity (TIBC), high ferritin
• DNormal serum iron, normal Total Iron Binding Capacity (TIBC), normal ferritin

Which of the following hormone patterns would be expected in a patient with primary hyperparathyroidism?

• ADecreased PTH, decreased calcium, increased phosphate
• BIncreased PTH, increased calcium, decreased phosphate
• CIncreased PTH, decreased calcium, increased phosphate
• DDecreased PTH, increased calcium, decreased phosphate

A patient is suspected of ingesting a toxic alcohol (such as methanol or ethylene glycol). Which of the following formulas is used to calculate the osmolal gap, and what value is considered clinically significant?

• AOsmolal Gap = Calculated Osmolality - Measured Osmolality; significant if > 5 mOsm/kg
• BOsmolal Gap = Measured Osmolality - Calculated Osmolality; significant if > 10 mOsm/kg
• COsmolal Gap = Measured Osmolality + Calculated Osmolality; significant if > 20 mOsm/kg
• DOsmolal Gap = Measured Osmolality / Calculated Osmolality; significant if > 1.5

Why is serum lipase considered a superior diagnostic marker for acute pancreatitis compared to serum amylase?

• AAmylase is only found in salivary glands and is not produced by the pancreas
• BLipase remains elevated longer (up to 7-14 days) and has greater clinical sensitivity and…
• CAmylase measurement requires a radioimmunoassay, whereas lipase is measured by simple col…
• DLipase levels rise within 30 minutes of onset, whereas amylase takes 24 hours to rise

A patient presents with a microcytic, hypochromic anemia. Laboratory results show: RBC Count = 5.8 x 10^12/L, Hemoglobin = 10.5 g/dL, Hematocrit = 32%, MCV = 55 fL, and RDW = 13.5%. Which of the following is the most likely diagnosis?

• AIron deficiency anemia
• BBeta-thalassemia minor (trait)
• CAnemia of chronic disease
• DSideroblastic anemia

Which of the following hemoglobin electrophoresis patterns (at alkaline pH) is most consistent with sickle cell trait (HbAS)?

• AHbA: 95%, HbA2: 2.5%, HbF: 1.5%
• BHbA: 0%, HbS: 90%, HbF: 8%, HbA2: 2%
• CHbA: 60%, HbS: 35%, HbA2: 3%, HbF: 2%
• DHbA: 0%, HbC: 95%, HbF: 3%, HbA2: 2%

A patient has an unexplained prolonged Activated Partial Thromboplastin Time (aPTT). A 1:1 mixing study is performed using normal pooled plasma. The immediate aPTT corrects from 68 seconds to 34 seconds (normal range 25-35 seconds). However, after incubation at 37°C for 2 hours, the mixture aPTT is 59 seconds. How should this mixing study be interpreted?

• ASimple coagulation factor deficiency
• BPresence of a fast-acting factor inhibitor (e.g., lupus anticoagulant)
• CPresence of a time- and temperature-dependent factor inhibitor (e.g., Factor VIII inhibit…
• DTechnically invalid test; the specimen must be recollected

Which of the following is the correct sequence of tests and results required to confirm the presence of a lupus anticoagulant (LA)?

• AScreening test (e.g., dRVVT) prolonged -> Mixing study corrects -> Confirmation test show…
• BScreening test prolonged -> Mixing study fails to correct -> Confirmation test showing sh…
• CScreening test shortened -> Mixing study corrects -> Confirmation test showing prolongati…
• DScreening test normal -> Mixing study fails to correct -> Confirmation test showing no ch…

Flow cytometric analysis of a peripheral blood specimen from a patient with suspected leukemia reveals a blast population expressing CD34, CD33, CD13, and CD117, but negative for CD3, CD19, and CD10. Which lineage does this immunophenotype represent?

• AT-lymphoblastic
• BB-lymphoblastic
• CMyeloid
• DMegakaryocytic

To differentiate Chronic Myeloid Leukemia (CML) from a leukemoid reaction, which of the following laboratory findings is most useful?

• AThe presence of toxic granulation and Döhle bodies in neutrophils
• BA markedly elevated white blood cell count
• CLeukocyte Alkaline Phosphatase (LAP) score and BCR-ABL1 cytogenetic testing
• DThe presence of a mild anemia

Which of the following correctly pairs an erythrocyte inclusion with its composition and the routine stain used for visualization?

• AHeinz bodies: denatured hemoglobin; visualized with Wright-Giemsa stain
• BHowell-Jolly bodies: DNA remnants; visualized with Wright-Giemsa stain
• CBasophilic stippling: precipitated iron; visualized with Prussian blue stain
• DPappenheimer bodies: precipitated RNA; visualized with supravital stain

Which of the following physiological factors decreases the Erythrocyte Sedimentation Rate (ESR)?

• AElevated plasma levels of fibrinogen
• BSevere anemia
• CPresence of sickle cells or spherocytes
• DPregnancy

A platelet aggregation study shows normal aggregation in response to ADP, epinephrine, and collagen, but absent aggregation with ristocetin. The addition of normal plasma (which contains Von Willebrand Factor) does not correct the abnormal ristocetin aggregation. Which of the following is the most likely diagnosis?

• AVon Willebrand Disease (vWD)
• BBernard-Soulier Syndrome
• CGlanzmann Thrombasthenia
• DAspirin ingestion

Why can testing for G6PD deficiency during or immediately after an acute hemolytic episode yield a false-negative result?

• AHemolytic toxins in the blood neutralize the assay substrate
• BYoung erythrocytes (reticulocytes) produced in response to anemia have higher G6PD enzyme…
• CFree hemoglobin released from lysed cells acts as a strong positive catalyst in the assay
• DThe G6PD enzyme becomes transiently hyperactive under acute oxidative stress

A patient's blood typing shows the following results: Forward Typing (patient's cells): Anti-A = 4+, Anti-B = 0. Reverse Typing (patient's serum): A1 cells = 1+, B cells = 4+. What is the most likely cause of this discrepancy?

• AThe patient is subgroup A2 and has developed an anti-A1 antibody
• BThe patient has acquired B antigen due to bacterial infection
• CThe patient has agammaglobulinemia
• DTechnical error of under-washing patient red blood cells

A donor's red blood cells forward type as Rh-negative (Anti-D = 0) at the immediate spin phase. However, upon addition of antihuman globulin (AHG) after incubation at 37°C (Indirect Antiglobulin Test), the result is 2+. What is the correct interpretation and disposition of this blood product?

• AThe donor is Rh-negative; the unit can be labeled and transfused as Rh-negative
• BThe donor is Weak D positive; the unit must be labeled and transfused as Rh-positive
• CThe donor has an autoantibody; the unit must be discarded
• DThe donor is Rh-positive; the unit should be transfused only to Rh-negative recipients

Which of the following clinical scenarios is the Direct Antiglobulin Test (DAT) specifically designed to detect?

• AUnexpected red cell antibodies in the recipient's serum prior to transfusion
• BIn vivo coating of the patient's red blood cells with immunoglobulins or complement
• CCompatibility between donor red cells and recipient serum
• DAntigenic profiling of donor red cells for rare blood group antigens

During emergency release of blood products for a patient in hemorrhagic shock, when the patient's blood type is unknown, which type of red cells and plasma should be selected?

• AO-positive red cells and AB-positive plasma
• BO-negative red cells and AB plasma
• CA-negative red cells and O plasma
• DO-negative red cells and O plasma

A Kleihauer-Betke test is performed on a postpartum maternal blood smear. The technician counts 20 fetal cells out of a total of 2000 red blood cells. What is the calculated percentage of fetal cells, and what is the estimated volume of fetal maternal hemorrhage (assuming a maternal blood volume of 5000 mL)?

• A0.1% fetal cells; 5 mL hemorrhage
• B1.0% fetal cells; 50 mL hemorrhage
• C2.0% fetal cells; 100 mL hemorrhage
• D10% fetal cells; 500 mL hemorrhage

Ten minutes into a red blood cell transfusion, a patient experiences fever, chills, back pain, and hypotension. The transfusion is stopped immediately. What is the first laboratory investigation sequence that must be performed on the post-transfusion specimen?

• ABacterial culture of the unit and patient's blood
• BClerical check, visual check for hemolysis in plasma, and Direct Antiglobulin Test (DAT)
• CRepeat crossmatch and antibody screen using the pre-transfusion sample only
• DHaptoglobin and serum bilirubin measurement

Which of the following clinical and laboratory findings helps distinguish Transfusion-Related Acute Lung Injury (TRALI) from Transfusion-Associated Circulatory Overload (TACO)?

• ATRALI is characterized by severe hypertension and elevated Brain Natriuretic Peptide (BNP…
• BTRALI features a normal to low BNP and normal pulmonary capillary wedge pressure (exudati…
• CTRALI is caused by red cell antibodies lysing lung tissue; TACO is caused by bacterial en…
• DOnly TRALI presents with bilateral pulmonary infiltrates on chest X-ray

A blood specimen is collected for a complete blood count (CBC). Upon running, the analyzer reports an falsely elevated mean corpuscular hemoglobin concentration (MCHC > 370 g/L) and a low red blood cell count. Visually, tiny clumps are visible in the purple-top tube. How should the technician handle this specimen?

• AReport the results as generated by the analyzer
• BDilute the sample 1:10 with distilled water and re-run
• CWarm the specimen to 37°C for 15-30 minutes and re-run immediately
• DPerform a manual platelet count to correct the RBC parameters

Which of the following blood group systems is most notoriously associated with delayed hemolytic transfusion reactions (DHTR) due to antibody titers that drop rapidly below detectable levels?

• AKidd system (Jka, Jkb)
• BKell system (K, k)
• CDuffy system (Fya, Fyb)
• DLewis system (Lea, Leb)

What is the correct storage temperature and maximum shelf life (using standard CPD anticoagulant-preservative) for packed red blood cells (PRBCs) and apheresis platelets?

• APRBCs: -20°C for 1 year; Platelets: 4°C for 35 days
• BPRBCs: 1-6°C for 21 days; Platelets: 20-24°C with continuous agitation for 5 days
• CPRBCs: 1-6°C for 42 days; Platelets: -80°C for 1 year
• DPRBCs: 20-24°C for 5 days; Platelets: 1-6°C for 35 days

During the Gram stain procedure, what is the exact mechanism by which Gram-negative bacteria lose the primary crystal violet-iodine complex during the decolorization step?

• ADecolorizer dissolves the thick peptidoglycan layer of Gram-negative cell walls
• BDecolorizer (acetone/alcohol) dissolves the lipid-rich outer membrane and increases perme…
• CDecolorizer chemically degrades the crystal violet dye molecule in Gram-negative cells
• DGram-negative cell walls contain teichoic acids which actively repel the dye complex in t…

A Gram-positive coccus is isolated from a wound culture. It is catalase-positive and coagulase-negative. To determine if this isolate is Staphylococcus saprophyticus, which antibiotic disk susceptibility test should be performed?

• AOptochin susceptibility
• BNovobiocin susceptibility
• CBacitracin susceptibility
• DPolymyxin B susceptibility

An isolate on Triple Sugar Iron (TSI) agar produces the following reaction: Alkaline slant / Acid butt (Alk/A), with gas production and a black precipitate in the medium. What does this reaction indicate regarding the organism's carbohydrate fermentation and hydrogen sulfide production?

• AFermentation of glucose, lactose, and sucrose; H2S produced
• BFermentation of glucose only; H2S produced
• CFermentation of lactose and sucrose only; H2S not produced
• DNo carbohydrate fermentation; H2S produced

A Gram-negative bacillus is isolated from a burn wound. It is oxidase-positive, produces a blue-green pigment (pyocyanin) on Mueller-Hinton agar, has a sweet, grape-like odor, and grows at 42°C. What is the most likely identification of this organism?

• AEscherichia coli
• BPseudomonas aeruginosa
• CStenotrophomonas maltophilia
• DAcinetobacter baumannii

Which of the following stains is considered a fluorochrome stain used for the rapid screening of sputum smears for Mycobacterium tuberculosis, and what color do the bacilli appear?

• AZiehl-Neelsen stain; red bacilli against blue background
• BAuramine-Rhodamine stain; bright yellow-orange fluorescent bacilli against dark background
• CKinyoun stain; blue bacilli against red background
• DGram stain; purple bacilli against pink background

Which of the following media is selective and differential for the isolation and presumptive identification of the Bacteroides fragilis group, and what is the characteristic colony appearance?

• AKanamycin-Vancomycin Laked Blood (KVLB) agar; red colonies
• BBacteroides Bile Esculin (BBE) agar; grey colonies surrounded by a dark brown/black zone
• CPhenylethyl Alcohol (PEA) agar; beta-hemolytic colonies
• DCycloserine Cefoxitin Fructose Agar (CCFA); yellow colonies with ground-glass appearance