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Kuwait MOH Medical Laboratory Technician practice questions

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Question 1Clinical Chemistry

In a healthy adult, which fasting plasma glucose value falls within the reference interval used for diagnosing normoglycemia by the American Diabetes Association?

  1. 92 mg/dL Correct answer.
  2. 130 mg/dL
  3. 145 mg/dL
  4. 118 mg/dL

Explanation

The ADA defines normal fasting plasma glucose as below 100 mg/dL (5.6 mmol/L). Values between 100 and 125 mg/dL indicate impaired fasting glucose, and 126 mg/dL or higher on repeat testing supports a diabetes diagnosis. Therefore only 92 mg/dL lies inside the normal reference interval.

Question 2Clinical Chemistry

Which specimen handling practice is most appropriate for a blood sample collected for measurement of plasma lactate?

  1. Store the tube at room temperature for two hours before centrifugation
  2. Collect into a plain tube without anticoagulant and allow complete clotting
  3. Place the tube immediately on ice and separate plasma promptly Correct answer.
  4. Expose the tube to air to allow equilibration with atmospheric oxygen

Explanation

Lactate rises artefactually when glycolysis continues in cells after collection, so the sample must be chilled immediately and plasma separated quickly. Cooling slows erythrocyte and leukocyte metabolism until centrifugation is complete. Prompt processing preserves the in vivo lactate concentration.

Question 3Clinical Chemistry

Which calculation correctly gives the anion gap from a routine electrolyte panel?

  1. Sodium minus the sum of chloride and bicarbonate Correct answer.
  2. Sodium plus potassium minus bicarbonate
  3. Chloride plus bicarbonate minus sodium
  4. Sodium minus chloride

Explanation

The anion gap estimates unmeasured anions by subtracting the measured anions chloride and bicarbonate from the measured cation sodium. The classic formula is Na − (Cl + HCO3), typically 8–12 mmol/L. It is used to classify metabolic acidosis into high-gap and normal-gap causes.

Question 4Clinical Chemistry

A serum sample shows visible hemolysis after centrifugation. Which analyte is most likely to be falsely increased by this hemolysis?

  1. Sodium
  2. Albumin
  3. Potassium Correct answer.
  4. Chloride

Explanation

Erythrocytes contain potassium at concentrations far above plasma, so lysis releases potassium into the serum and falsely elevates the result. Sodium and chloride are distributed differently and are less affected. Albumin is not concentrated in red cells and is not typically raised by hemolysis.

Question 5Clinical Chemistry

Which enzyme is considered the most liver-specific marker of cholestasis among the following?

  1. Alkaline phosphatase Correct answer.
  2. Creatine kinase
  3. Lactate dehydrogenase
  4. Amylase

Explanation

Alkaline phosphatase is concentrated in the canalicular membrane of hepatocytes and rises markedly when bile flow is obstructed. Its elevation in cholestasis is disproportionate to that of transaminases. The other enzymes listed originate mainly from muscle, ubiquitous tissue, or pancreas.

Question 6Clinical Chemistry

A patient with chronic kidney disease has a serum creatinine of 3.0 mg/dL. Which additional measurement is required to calculate estimated glomerular filtration rate using the CKD-EPI equation?

  1. Hemoglobin
  2. Age and sex Correct answer.
  3. Serum albumin
  4. Serum potassium

Explanation

The CKD-EPI creatinine equation incorporates serum creatinine together with age and sex to estimate glomerular filtration rate. Albumin, hemoglobin, and potassium are not variables in that equation. Without age and sex the estimate cannot be computed.

Question 7Clinical Chemistry

Which lipid fraction is the primary carrier of endogenously synthesized triglycerides from the liver to peripheral tissues?

  1. High-density lipoprotein
  2. Very-low-density lipoprotein Correct answer.
  3. Low-density lipoprotein
  4. Chylomicrons

Explanation

Very-low-density lipoprotein is assembled in the liver and transports endogenous triglycerides to peripheral tissues. Chylomicrons carry dietary fat from the intestine. LDL delivers cholesterol and HDL participates in reverse cholesterol transport.

Question 8Clinical Chemistry

Which condition typically produces a low serum total calcium with a normal albumin-corrected calcium?

  1. Hypoalbuminemia Correct answer.
  2. Vitamin D intoxication
  3. Milk-alkali syndrome
  4. Primary hyperparathyroidism

Explanation

Roughly 40 percent of calcium is albumin-bound, so low albumin lowers total calcium without changing the physiologically active ionized fraction. Correcting total calcium for albumin restores the value to normal. The other conditions raise calcium rather than lower it.

Question 9Clinical Chemistry

A patient presents with a serum sodium of 155 mmol/L and a serum glucose of 600 mg/dL. Which statement best describes the relationship between glucose and measured sodium?

  1. Hyperglycemia has no measurable effect on sodium
  2. Hyperglycemia raises measured sodium by osmotic diuresis
  3. Hyperglycemia lowers measured sodium by dilutional effect Correct answer.
  4. Hyperglycemia increases sodium by stimulating aldosterone

Explanation

Marked hyperglycemia draws water from cells into the extracellular space, diluting sodium and producing pseudohyponatremia when sodium is measured in whole plasma. The measured sodium falls as glucose rises. Corrected sodium can be estimated by adding 1.6 mmol/L for every 100 mg/dL of glucose above normal.

Question 10Clinical Chemistry

Which pattern of arterial blood gases is most consistent with uncompensated metabolic acidosis?

  1. pH 7.50, HCO3 30 mmol/L, pCO2 45 mmHg
  2. pH 7.30, HCO3 15 mmol/L, pCO2 35 mmHg Correct answer.
  3. pH 7.30, HCO3 24 mmol/L, pCO2 55 mmHg
  4. pH 7.48, HCO3 24 mmol/L, pCO2 30 mmHg

Explanation

Metabolic acidosis shows a low pH with a primary reduction in bicarbonate. The pCO2 here is near normal, indicating little respiratory compensation. The other patterns describe respiratory acidosis, respiratory alkalosis, or metabolic alkalosis.

Question 11Clinical Chemistry

Which cardiac marker is considered the most specific for myocardial injury because it is not expressed in skeletal muscle?

  1. CK-MB
  2. Creatine kinase total
  3. Troponin I Correct answer.
  4. Myoglobin

Explanation

Cardiac troponin I is encoded by a gene expressed only in myocardium, giving it high specificity for cardiac injury. CK-MB can rise with skeletal muscle damage, and myoglobin is abundant in muscle generally. Total CK is even less cardiac-specific.

Question 12Clinical Chemistry

A serum sample for bilirubin assay is left on the benchtop exposed to direct sunlight for several hours. What is the most likely effect on the measured bilirubin?

  1. Unchanged because bilirubin is stable at room temperature
  2. Falsely increased because hemoglobin is released
  3. Falsely increased because albumin binds more bilirubin
  4. Falsely decreased because bilirubin is photolabile Correct answer.

Explanation

Bilirubin is degraded by light, particularly blue and ultraviolet wavelengths, so prolonged light exposure lowers measured concentrations. Specimens should be protected from light during collection and storage. This is why neonatal bilirubin samples are wrapped in foil or amber tubes.

Question 13Clinical Chemistry

Which urea-to-creatinine ratio pattern is most suggestive of a pre-renal cause of azotemia?

  1. Elevated urea with normal creatinine Correct answer.
  2. Elevated creatinine with normal urea
  3. Both urea and creatinine decreased
  4. Both urea and creatinine elevated equally with normal ratio

Explanation

In pre-renal azotemia, reduced renal perfusion increases proximal tubular urea reabsorption while creatinine is not reabsorbed, so urea rises disproportionately. This produces a high urea-to-creatinine ratio. Intrinsic renal failure tends to raise both more proportionally.

Question 14Clinical Chemistry

A patient's serum shows a monoclonal spike on protein electrophoresis. Which follow-up test is most appropriate for quantifying the monoclonal immunoglobulin?

  1. Serum total protein
  2. C-reactive protein
  3. Serum albumin
  4. Densitometric quantification of the M-spike on serum protein electrophoresis Correct answer.

Explanation

Densitometry measures the proportion of total protein within the monoclonal band; combining this with serum total protein gives the M-protein concentration. Immunofixation identifies the immunoglobulin type, while the free light chain ratio assesses light chain imbalance. Neither replaces M-spike quantification.

Question 15Clinical Chemistry

Which preanalytical factor most strongly affects measured serum phosphate?

  1. Use of a lithium heparin tube
  2. Exposure to light
  3. Delayed separation of serum from cells Correct answer.
  4. Fasting status of the patient

Explanation

Phosphate is released from erythrocytes and platelets during clotting and storage, so prolonged contact of serum with cells raises the result. Prompt separation limits this positive interference. Light exposure and fasting status have minimal effect on phosphate.

Question 16Clinical Chemistry

Which hormone is measured to assess thyroid function at the level of the pituitary feedback loop?

  1. Thyroid-stimulating hormone Correct answer.
  2. Thyroglobulin
  3. Thyroxine-binding globulin
  4. Triiodothyronine

Explanation

Thyroid-stimulating hormone is secreted by the anterior pituitary and rises when circulating thyroid hormone falls, making it a sensitive indicator of the feedback axis. It is the first-line test for thyroid dysfunction. Thyroglobulin and binding globulin serve different purposes.

Question 17Clinical Chemistry

Which finding is most consistent with primary hypothyroidism?

  1. Low TSH with low free T4
  2. High TSH with high free T4
  3. Low TSH with high free T4
  4. High TSH with low free T4 Correct answer.

Explanation

In primary hypothyroidism the thyroid gland fails, so free T4 falls and the pituitary responds with increased TSH. The combination of high TSH and low free T4 is the classic pattern. Low TSH with low free T4 points instead to central hypothyroidism.

Question 18Clinical Chemistry

Which statement correctly describes the relationship between ionized calcium and pH?

  1. Alkalosis decreases the fraction of calcium bound to albumin
  2. pH has no effect on calcium binding
  3. Ionized calcium falls as pH rises Correct answer.
  4. Acidosis increases protein-bound calcium

Explanation

Hydrogen ions and calcium compete for binding sites on albumin. As pH rises and hydrogen ions decrease, more calcium binds to albumin, so ionized calcium falls. Conversely, acidosis releases calcium from albumin and raises the ionized fraction.

Question 19Clinical Chemistry

A laboratory reports a serum osmolality of 300 mOsm/kg while the calculated osmolality from sodium, glucose, and urea is 270 mOsm/kg. Which explanation best accounts for this discrepancy?

  1. Improper calibration of the freezing-point osmometer
  2. Presence of an unmeasured osmotically active substance Correct answer.
  3. Sample contamination with distilled water
  4. Normal analytical variation of less than 5 mOsm/kg

Explanation

An osmolal gap of about 30 mOsm/kg exceeds normal analytical variation and suggests an unmeasured solute such as ethanol, methanol, ethylene glycol, or isopropanol. The gap is calculated as measured minus calculated osmolality. Identifying the gap guides toxicological investigation.

Question 20Clinical Chemistry

Which enzyme pattern is most characteristic of acute hepatocellular injury?

  1. Isolated creatine kinase elevation
  2. Marked alkaline phosphatase elevation with mild ALT rise
  3. Isolated amylase elevation
  4. Marked ALT and AST elevation with mild alkaline phosphatase rise Correct answer.

Explanation

Hepatocellular injury releases transaminases, so ALT and AST rise disproportionately while alkaline phosphatase changes little. Cholestatic patterns show the opposite, with alkaline phosphatase predominating. This distinction helps localize the type of liver disease.

Question 21Clinical Chemistry

Which analytical principle underlies the Jaffe reaction for creatinine measurement?

  1. Binding of creatinine to a specific antibody
  2. Formation of a colored complex between creatinine and picrate in alkaline solution Correct answer.
  3. Enzymatic oxidation of creatinine to creatine by creatininase
  4. Reduction of creatinine by glucose oxidase

Explanation

The Jaffe method uses alkaline picrate, which reacts with creatinine to form a red-orange complex measured photometrically. The reaction is not entirely specific because non-creatinine chromogens such as glucose and ketones can interfere. Modern enzymatic methods reduce this interference.

Question 22Clinical Chemistry

A patient with diabetic ketoacidosis has a serum bicarbonate of 10 mmol/L and a blood pH of 7.20. Which compensatory response is expected?

  1. Increased bicarbonate reabsorption by the kidney
  2. Renal retention of hydrogen ions
  3. Hyperventilation lowering pCO2 Correct answer.
  4. Hypoventilation raising pCO2

Explanation

Metabolic acidosis stimulates the respiratory center, producing hyperventilation that lowers pCO2 and partially restores pH. This respiratory compensation begins within minutes. Renal compensation through bicarbonate reabsorption develops over days and does not correct an acute ketoacidosis.

Question 23Clinical Chemistry

A serum sample from a patient receiving high-dose intravenous vitamin C gives a falsely low result for which analyte when measured by a peroxidase-based assay?

  1. Glucose
  2. Creatinine Correct answer.
  3. Uric acid
  4. Total protein

Explanation

High concentrations of ascorbic acid consume hydrogen peroxide in peroxidase-coupled reactions, reducing color development and producing falsely low results. Creatinine assays using Trinder-type peroxidase detection are particularly susceptible. This interference is a known cause of spurious creatinine values.

Question 24Clinical Chemistry

A patient with severe pancreatitis has a serum calcium of 7.2 mg/dL and an albumin of 3.0 g/dL. Correcting for albumin, which interpretation is most accurate?

  1. The corrected calcium is elevated, suggesting hypercalcemia
  2. The corrected calcium remains low, suggesting true hypocalcemia Correct answer.
  3. Albumin correction cannot be applied in pancreatitis
  4. The corrected calcium is normal, indicating no true hypocalcemia

Explanation

Corrected calcium equals measured calcium plus 0.8 times the difference between 4.0 and the albumin in g/dL, giving 7.2 + 0.8 = 8.0 mg/dL, still below the reference interval. Saponification of fat in pancreatitis binds calcium and causes true hypocalcemia. This finding is a marker of severe disease.

Question 25Clinical Chemistry

Which situation produces a falsely elevated measured osmolality by freezing-point depression but not by vapor-pressure osmometry?

  1. Presence of volatile alcohols such as ethanol Correct answer.
  2. Severe hyperproteinemia
  3. Marked hyperglycemia
  4. Presence of large amounts of lipid in the sample

Explanation

Volatile solutes such as ethanol contribute to osmolality measured by freezing-point depression but evaporate during vapor-pressure osmometry, so the two methods disagree. This discrepancy can be used to detect volatile ingestion. Non-volatile solutes like glucose and electrolytes affect both methods similarly.

Question 26Clinical Chemistry

In a fasting serum sample, which lipoprotein fraction normally contains the highest concentration of cholesterol in a healthy adult?

  1. High-density lipoprotein (HDL)
  2. Very-low-density lipoprotein (VLDL)
  3. Chylomicrons
  4. Low-density lipoprotein (LDL) Correct answer.

Explanation

In fasting adults, LDL carries roughly 60-70% of total serum cholesterol, making it the dominant cholesterol-carrying fraction. HDL carries about 20-30%, while VLDL and chylomicrons carry mostly triglyceride and little cholesterol. Chylomicrons are also essentially absent after a proper fast.

Question 27Clinical Chemistry

A serum sample is hemolyzed during phlebotomy. Which measured analyte is most likely to be falsely elevated as a direct result of red cell contents entering the plasma?

  1. Sodium
  2. Potassium Correct answer.
  3. Albumin
  4. Chloride

Explanation

Red blood cells contain potassium at a concentration many times higher than plasma, so hemolysis releases potassium into the sample and produces a spuriously high result. Sodium, chloride, and albumin are distributed differently and are far less affected by mild hemolysis. This is why potassium results from hemolyzed specimens should be interpreted with caution or rejected.

Question 28Clinical Chemistry

A patient with a fasting serum glucose of 130 mg/dL on two separate occasions has a glycated hemoglobin (HbA1c) of 6.0%. How should these results be interpreted for diabetes classification?

  1. Both results are normal and no further testing is needed
  2. Both results are diagnostic of diabetes because HbA1c of 6.0% exceeds the diagnostic cutoff
  3. The fasting glucose meets the diagnostic threshold for diabetes, while the HbA1c falls in the prediabetes range Correct answer.
  4. The HbA1c is diagnostic of diabetes while the fasting glucose indicates prediabetes

Explanation

A fasting plasma glucose of 126 mg/dL or higher is diagnostic of diabetes, so 130 mg/dL on two occasions meets that criterion. HbA1c values of 5.7-6.4% indicate prediabetes, and 6.0% falls in that interval. Discordant results like this are common and the fasting glucose criterion alone is sufficient to classify the patient.

Question 29Clinical Chemistry

An arterial blood gas from a patient with persistent vomiting shows pH 7.48, pCO2 46 mmHg, and bicarbonate 34 mmol/L. Which acid-base disturbance does this pattern represent?

  1. Metabolic alkalosis with respiratory compensation Correct answer.
  2. Respiratory acidosis with metabolic compensation
  3. Metabolic acidosis with respiratory compensation
  4. Respiratory alkalosis with metabolic compensation

Explanation

The elevated pH indicates alkalosis, and the elevated bicarbonate identifies the metabolic origin. Vomiting causes loss of gastric acid and a rise in bicarbonate. The raised pCO2 reflects hypoventilation as respiratory compensation, which is expected in a primary metabolic alkalosis.

Question 30Clinical Chemistry

A serum sample for free (ionized) calcium is collected in a plain tube and left unopened for four hours before analysis. What is the most likely effect on the measured ionized calcium?

  1. It will remain unchanged because ionized calcium is unaffected by storage
  2. It will fall because calcium binds to albumin as the sample pH rises Correct answer.
  3. It will rise because calcium is released from red cells
  4. It will fall because calcium is consumed by clot formation

Explanation

When blood is left in a sealed tube, carbon dioxide accumulates and the pH rises; the resulting alkalosis increases the negative charge on albumin, so more calcium binds and ionized calcium falls. This is why ionized calcium should be measured promptly or in a sample handled to preserve pH. The effect is a shift in calcium distribution, not consumption or red cell release.

Question 31Hematology and Coagulation

Which anticoagulant is the standard choice for a complete blood count (CBC) specimen in a Kuwait MOH hematology laboratory?

  1. Lithium heparin
  2. Sodium fluoride/oxalate
  3. K2 or K3 EDTA Correct answer.
  4. Sodium citrate 3.2%

Explanation

EDTA binds calcium and also preserves cell morphology and platelet counts well, so it is the reference anticoagulant for automated CBC and blood film work. It is used at roughly 1.8 mg/mL of blood, and overfilling or underfilling the tube distorts results.

Question 32Hematology and Coagulation

A blood film shows a neutrophil with a dark blue, irregular nuclear appendage attached by a thin chromatin thread. What is this structure called?

  1. Auer rod
  2. Howell-Jolly body
  3. Toxic granulation
  4. Barr body (drumstick) Correct answer.

Explanation

The drumstick is a condensed X chromosome seen as a small lobed appendage on the nucleus of neutrophils in females. It is counted as a sex-chromatin marker and must be distinguished from a sessile nodule, which lacks the thin stalk.

Question 33Hematology and Coagulation

Which red cell index is calculated directly from the measured hemoglobin and red cell count, and is expressed in picograms?

  1. MCHC
  2. RDW
  3. MCV
  4. MCH Correct answer.

Explanation

MCH equals hemoglobin concentration divided by red cell count, giving the average hemoglobin content per cell in picograms. It falls in iron deficiency and microcytic anemia and is derived rather than directly measured.

Question 34Hematology and Coagulation

A patient's EDTA sample shows platelet clumping on the film and a low automated platelet count of 45 x 10^9/L, while the patient has no bleeding. What is the most appropriate next step?

  1. Perform a bleeding time test
  2. Request a bone marrow aspirate immediately
  3. Repeat the count on a citrate tube and correct for dilution Correct answer.
  4. Report the count as true thrombocytopenia

Explanation

Platelet clumping in EDTA is a common preanalytical artefact caused by EDTA-dependent agglutinins, producing a spuriously low count. Recollecting in citrate and applying the dilution correction factor confirms whether true thrombocytopenia exists.

Question 35Hematology and Coagulation

In the international normalized ratio (INR) calculation, which value is used as the denominator?

  1. The activated partial thromboplastin time
  2. The mean normal prothrombin time Correct answer.
  3. The patient's prothrombin time divided by the mean normal prothrombin time
  4. The thrombin time

Explanation

The INR is the ratio of the patient prothrombin time to the geometric mean normal prothrombin time, raised to the power of the ISI. The mean normal PT is established locally from at least 20 healthy donors using the same thromboplastin lot.

Question 36Hematology and Coagulation

A 30-year-old woman has microcytic hypochromic red cells, a low serum ferritin and a raised total iron-binding capacity. Which condition best fits these findings?

  1. Thalassemia trait
  2. Sideroblastic anemia
  3. Anemia of chronic disease
  4. Iron deficiency anemia Correct answer.

Explanation

Low ferritin with raised TIBC and microcytic hypochromic indices is the classic pattern of iron deficiency anemia. Ferritin reflects depleted stores, and the transferrin rise represents the compensatory increase in iron-binding capacity.

Question 37Hematology and Coagulation

Which hemoglobin is the major adult form and consists of two alpha and two beta globin chains?

  1. HbA Correct answer.
  2. HbA2
  3. HbF
  4. HbH

Explanation

HbA makes up about 95 to 97 percent of adult hemoglobin and comprises two alpha and two beta chains. HbA2 and HbF are minor adult fractions, and HbH is a pathological tetramer of beta chains.

Question 38Hematology and Coagulation

On a peripheral film, a red cell shows an even, slate-grey or blue-grey tint throughout the cytoplasm without a distinct punctate pattern. This appearance is described as:

  1. Polychromasia Correct answer.
  2. Basophilic stippling
  3. Howell-Jolly bodies
  4. Pappenheimer bodies

Explanation

Polychromasia is the diffuse blue-grey tint of a young red cell that still contains residual RNA, and it indicates reticulocytosis. It differs from stippling, which is punctate, and from inclusion bodies, which are discrete structures.

Question 39Hematology and Coagulation

Which of the following best describes the principle of impedance platelet counting in an automated analyzer?

  1. Cells are separated by density gradient before counting
  2. Cells are sized by the change in electrical resistance as they pass an aperture Correct answer.
  3. Platelets are counted by light absorbance at 540 nm
  4. Platelets are counted by monoclonal antibody fluorescence only

Explanation

In impedance counting, cells suspended in electrolyte pass through an aperture and generate a voltage pulse proportional to cell volume. Platelets are discriminated from red cells by their smaller pulse size, though very large platelets or fragments can cause errors.

Question 40Hematology and Coagulation

A prolonged APTT that corrects fully after mixing with normal plasma at 37 degrees Celsius for 2 hours suggests which cause?

  1. A direct thrombin inhibitor
  2. A clotting factor deficiency Correct answer.
  3. A lupus anticoagulant
  4. Heparin contamination

Explanation

Correction of a prolonged APTT by normal plasma indicates a deficiency of one or more intrinsic or common pathway factors, because normal plasma supplies the missing factor. Failure to correct points toward an inhibitor such as a lupus anticoagulant or a drug effect.

Question 41Hematology and Coagulation

Which test is most appropriate to monitor unfractionated heparin therapy?

  1. Prothrombin time
  2. Activated partial thromboplastin time Correct answer.
  3. Thrombin time
  4. Fibrinogen assay

Explanation

Unfractionated heparin potentiates antithrombin and prolongs the intrinsic pathway, so the APTT is used to monitor its therapeutic range. The target is usually an APTT ratio of 1.5 to 2.5 times control, or an anti-Xa level in some laboratories.

Question 42Hematology and Coagulation

A patient has a hemoglobin of 70 g/L, MCV of 118 fL and a peripheral film showing oval macrocytes and hypersegmented neutrophils. Which deficiency is most likely?

  1. Chronic blood loss
  2. Alpha thalassemia trait
  3. Vitamin B12 or folate deficiency Correct answer.
  4. Iron deficiency

Explanation

Megaloblastic anemia from vitamin B12 or folate deficiency produces oval macrocytes and neutrophil hypersegmentation, with a raised MCV. The nuclear-cytoplasmic asynchrony reflects impaired DNA synthesis in the marrow.

Question 43Hematology and Coagulation

Which finding on a blood film is most characteristic of hereditary spherocytosis?

  1. Numerous spherocytes with loss of central pallor Correct answer.
  2. Bite cells and blister cells
  3. Sickle-shaped cells
  4. Target cells with a central bullseye

Explanation

Hereditary spherocytosis results from membrane protein defects that cause loss of membrane surface area, producing dense round cells with no central pallor. Spherocytes are also seen in immune hemolysis, so the family history and osmotic fragility or EMA binding test help confirm the diagnosis.

Question 44Hematology and Coagulation

In a patient with suspected disseminated intravascular coagulation, which combination of results is most typical?

  1. Normal platelets, normal PT, isolated raised fibrinogen
  2. Thrombocytopenia, prolonged PT and APTT, low fibrinogen, raised D-dimer Correct answer.
  3. Raised platelets, shortened PT, raised fibrinogen
  4. Thrombocytosis with normal coagulation screen

Explanation

DIC consumes platelets and coagulation factors while activating fibrinolysis, so platelets and fibrinogen fall, clotting times lengthen and D-dimer rises. Serial monitoring of these parameters guides replacement therapy.

Question 45Hematology and Coagulation

What is the main purpose of adding citrated anticoagulant at a fixed 1:9 ratio of citrate to blood in coagulation tubes?

  1. To activate the contact pathway
  2. To chelate calcium and prevent clotting while preserving factor activity Correct answer.
  3. To lyse red cells before testing
  4. To preserve platelet function for aggregation studies

Explanation

Sodium citrate binds ionised calcium, which is required for coagulation factor activation, and recalcification during testing restores clotting. The fixed ratio ensures reproducible dilution, so underfilled tubes give falsely prolonged clotting times.

Question 46Hematology and Coagulation

A patient with chronic kidney disease has normocytic normochromic anemia with a low reticulocyte count and normal iron studies. Which mechanism best explains the anemia?

  1. Reduced erythropoietin production Correct answer.
  2. Acute blood loss
  3. Autoimmune red cell destruction
  4. Vitamin B12 malabsorption

Explanation

The kidneys produce erythropoietin, so chronic kidney disease reduces erythropoietic drive and gives a hypoproliferative normocytic normochromic anemia. Reticulocytes are inappropriately low for the degree of anemia, and iron studies are typically unremarkable.

Question 47Hematology and Coagulation

Which laboratory finding best distinguishes immune thrombocytopenia from decreased platelet production?

  1. Low platelet count with raised reticulocyte count
  2. Low platelet count with prolonged bleeding time
  3. Low platelet count with increased mean platelet volume and large platelets on film Correct answer.
  4. Low platelet count with normal mean platelet volume

Explanation

In immune thrombocytopenia, destruction drives marrow to release young, larger platelets, so the mean platelet volume is often raised and large platelets appear on the film. Reduced production usually gives smaller or normal-sized platelets with a hypoproliferative marrow.

Question 48Hematology and Coagulation

Which hemoglobin separation technique is considered the reference method for quantifying HbA2 and identifying hemoglobin variants?

  1. Capillary tube centrifugation
  2. Sickling test
  3. High-performance liquid chromatography Correct answer.
  4. Cellulose acetate electrophoresis at alkaline pH

Explanation

Cation-exchange HPLC separates hemoglobins by charge with high resolution and reliable quantification of HbA2 and HbF, making it the reference method in many laboratories. It also flags abnormal variants for further study.

Question 49Hematology and Coagulation

What is the typical reference range for the prothrombin time in a healthy adult when using a sensitive thromboplastin reagent?

  1. About 11 to 14 seconds Correct answer.
  2. About 25 to 35 seconds
  3. About 5 to 8 seconds
  4. About 60 to 70 seconds

Explanation

Prothrombin time in healthy adults is usually around 11 to 14 seconds, depending on the thromboplastin reagent and analyzer. Each laboratory must establish its own reference interval and mean normal PT for INR calculation.

Question 50Hematology and Coagulation

A 45-year-old man has polycythemia with a raised red cell mass, low erythropoietin and an acquired JAK2 V617F mutation. Which diagnosis is most likely?

  1. Polycythemia vera Correct answer.
  2. Thalassemia intermedia
  3. Relative polycythemia from dehydration
  4. Secondary polycythemia due to hypoxia

Explanation

Polycythemia vera is a myeloproliferative neoplasm with an autonomous red cell increase, suppressed erythropoietin and a clonal JAK2 mutation in most cases. The low erythropoietin distinguishes it from secondary polycythemia driven by hypoxia.