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Egyptian Board Clinical Pathology study materials
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Egyptian Board Clinical Pathology practice questions

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Question 1Chemical Pathology (Clinical Biochemistry)

A 24-year-old man with type 1 diabetes presents with nausea, deep sighing respiration and a fruity odour on the breath. Capillary glucose is 28 mmol/L and blood ketones are 5.2 mmol/L. Which acid-base picture is most consistent with this presentation?

  1. Mixed metabolic alkalosis and respiratory acidosis
  2. High anion gap metabolic acidosis with compensatory respiratory alkalosis Correct answer.
  3. Primary respiratory alkalosis with renal compensation
  4. Normal anion gap metabolic acidosis with a raised chloride

Explanation

Diabetic ketoacidosis accumulates acetoacetate and beta-hydroxybutyrate, which are unmeasured anions, so the anion gap rises and bicarbonate falls. The resulting metabolic acidosis drives hyperventilation (Kussmaul breathing), lowering PaCO2 as respiratory compensation.

Question 2Chemical Pathology (Clinical Biochemistry)

Which laboratory measurement is the most reliable single indicator of long-term glycaemic control over the preceding two to three months?

  1. Random capillary glucose
  2. Urinary glucose on a first-morning sample
  3. Fasting plasma glucose
  4. Glycated haemoglobin (HbA1c) Correct answer.

Explanation

HbA1c reflects glucose exposure over the erythrocyte lifespan, giving an integrated picture of glycaemia over roughly 8 to 12 weeks. Single glucose measurements and urine glucose are affected by acute fluctuations and renal threshold.

Question 3Chemical Pathology (Clinical Biochemistry)

A patient with chronic kidney disease has a serum creatinine of 320 micromol/L. Which statement best explains why serum creatinine is an imperfect marker of glomerular filtration rate?

  1. It is freely filtered and completely reabsorbed, so it overestimates glomerular filtration
  2. It is produced by the liver and is unaffected by renal function
  3. It is secreted by the renal tubules and rises only after filtration has ceased
  4. Its generation depends on muscle mass, so it may appear normal despite reduced filtration Correct answer.

Explanation

Creatinine is generated from muscle creatine, so production varies with muscle mass, age, sex and diet. A low-muscle patient can have a near-normal creatinine despite substantially reduced glomerular filtration. Tubular secretion also makes creatinine slightly overestimate filtration.

Question 4Chemical Pathology (Clinical Biochemistry)

Which set of findings best fits primary hypothyroidism of autoimmune origin?

  1. High TSH with high free T4 and a thyroid-binding globulin excess
  2. High TSH with low free T4 and positive anti-thyroid peroxidase antibodies Correct answer.
  3. Low TSH with low free T4 and a pituitary mass
  4. Low TSH with high free T4

Explanation

In primary hypothyroidism the thyroid gland fails, so free T4 falls and the pituitary drives TSH up. Hashimoto thyroiditis is the commonest cause and is marked by anti-thyroid peroxidase antibodies.

Question 5Chemical Pathology (Clinical Biochemistry)

A 55-year-old woman has a serum calcium of 2.85 mmol/L (reference 2.15-2.55), a phosphate of 0.70 mmol/L and an inappropriately normal PTH. Which diagnosis is most likely?

  1. Hypoparathyroidism
  2. Chronic kidney disease with secondary hyperparathyroidism
  3. Vitamin D deficiency
  4. Primary hyperparathyroidism Correct answer.

Explanation

Hypercalcaemia with hypophosphataemia and a non-suppressed PTH is the classic biochemical signature of primary hyperparathyroidism. PTH raises calcium by bone resorption and renal reabsorption while promoting phosphate excretion.

Question 6Chemical Pathology (Clinical Biochemistry)

In a patient with suspected acute pancreatitis, which enzyme pattern is most supportive of the diagnosis?

  1. Creatine kinase elevated more than three times the upper reference limit
  2. Alkaline phosphatase elevated more than three times the upper reference limit
  3. Lipase elevated more than three times the upper reference limit Correct answer.
  4. Troponin elevated more than three times the upper reference limit

Explanation

Serum lipase rises within hours of pancreatic injury and a value above three times the upper reference limit is widely used as a diagnostic criterion. Lipase is more pancreas-specific and stays elevated longer than amylase.

Question 7Chemical Pathology (Clinical Biochemistry)

A 19-year-old presents with episodic palpitations and sweating. Plasma metanephrines are markedly elevated. Which pre-analytical factor is most important to control when interpreting this result?

  1. Dietary fibre intake on the day of sampling
  2. Serum sodium concentration
  3. Posture and prior catecholamine-releasing stressors such as vigorous exercise Correct answer.
  4. Time since the last meal only

Explanation

Catecholamine and metanephrine concentrations are sensitive to posture, stress, exercise and drugs, so sampling conditions must be standardised. Supine rest before sampling reduces false elevations from sympathetic activation.

Question 8Chemical Pathology (Clinical Biochemistry)

Which laboratory pattern is most characteristic of SIADH (syndrome of inappropriate antidiuretic hormone secretion)?

  1. Euvolaemic hyponatraemia with high urine osmolality and high urine sodium Correct answer.
  2. Hypovolaemic hyponatraemia with low urine sodium
  3. Hyperkalaemia with metabolic acidosis
  4. Hypernatraemia with dilute urine

Explanation

SIADH causes water retention, so serum sodium falls while urine remains inappropriately concentrated. The patient is clinically euvolaemic and urine sodium is typically high because of volume expansion and natriuretic factors.

Question 9Chemical Pathology (Clinical Biochemistry)

A 62-year-old man with known alcoholic liver disease has a prolonged prothrombin time. Which additional test best distinguishes a vitamin K deficiency from hepatocellular synthetic failure?

  1. Factor VIII activity Correct answer.
  2. Reticulocyte count
  3. Serum amylase
  4. Serum magnesium

Explanation

Factor VIII is produced by the vascular endothelium rather than the liver, so it is preserved or raised in hepatocellular failure while vitamin K-dependent factors fall. In vitamin K deficiency, factor VIII is unaffected and the prothrombin time corrects with vitamin K.

Question 10Chemical Pathology (Clinical Biochemistry)

Which finding best supports a diagnosis of haemolysis in a patient with anaemia?

  1. Isolated rise in alkaline phosphatase with normal bilirubin
  2. Raised conjugated bilirubin with normal haptoglobin and low lactate dehydrogenase
  3. Low unconjugated bilirubin with raised haptoglobin
  4. Raised unconjugated bilirubin with low haptoglobin and raised lactate dehydrogenase Correct answer.

Explanation

Intravascular and extravascular haemolysis release haemoglobin, which binds and depletes haptoglobin, while red cell breakdown raises unconjugated bilirubin and LDH. This triad is the standard biochemical signature of haemolysis.

Question 11Chemical Pathology (Clinical Biochemistry)

A patient with type 2 diabetes has an eGFR of 25 mL/min/1.73m2. Which change in laboratory monitoring is most appropriate?

  1. Use urinary glucose as the primary marker of control
  2. Stop measuring electrolytes because they are unaffected by renal function
  3. Interpret HbA1c with caution because anaemia and altered red cell survival affect it Correct answer.
  4. Rely on serum creatinine alone because it remains accurate at all levels of renal function

Explanation

In advanced chronic kidney disease, anaemia, erythropoietin deficiency and altered red cell survival reduce the reliability of HbA1c. Creatinine-based estimates also lose accuracy, so cystatin C or measured clearance may be preferred.

Question 12Chemical Pathology (Clinical Biochemistry)

Which is the most appropriate first-line biochemical test when screening for suspected phaeochromocytoma?

  1. Plasma renin activity
  2. Serum cortisol at midnight
  3. Plasma free metanephrines Correct answer.
  4. Serum aldosterone

Explanation

Plasma free metanephrines are the most sensitive initial test for phaeochromocytoma because they are produced continuously within the tumour. Cortisol, renin and aldosterone address different endocrine axes.

Question 13Chemical Pathology (Clinical Biochemistry)

A 34-year-old woman has a serum sodium of 128 mmol/L, serum osmolality of 262 mOsm/kg and a normal measured glucose. Which additional measurement is most useful in confirming true hypotonic hyponatraemia?

  1. Serum alkaline phosphatase
  2. Serum creatine kinase
  3. Serum total protein
  4. Serum osmolality compared with calculated osmolality to detect unmeasured osmoles Correct answer.

Explanation

Comparing measured with calculated osmolality detects osmolar gaps caused by unmeasured solutes such as mannitol, ethanol or glycine. This distinguishes true hypotonic hyponatraemia from pseudohyponatraemia or translocational hyponatraemia.

Question 14Chemical Pathology (Clinical Biochemistry)

Which biochemical abnormality is most typical of untreated Addison disease?

  1. Hyponatraemia with hyperkalaemia and metabolic acidosis Correct answer.
  2. Hypoglycaemia with respiratory alkalosis
  3. Hypercalcaemia with hyperphosphataemia
  4. Hypernatraemia with hypokalaemia and alkalosis

Explanation

Aldosterone deficiency causes sodium loss and potassium retention, producing hyponatraemia and hyperkalaemia. Loss of glucocorticoid and mineralocorticoid activity also causes a mild metabolic acidosis.

Question 15Chemical Pathology (Clinical Biochemistry)

A patient with suspected nephrotic syndrome has a 24-hour urinary protein of 5.2 g. Which additional biochemical finding is most consistent with this syndrome?

  1. Raised serum albumin with normal lipids
  2. Low LDL cholesterol with low triglycerides
  3. Hyperalbuminaemia with raised total protein
  4. Hypoalbuminaemia with hyperlipidaemia Correct answer.

Explanation

Heavy urinary protein loss depletes serum albumin and stimulates hepatic lipoprotein synthesis, producing hyperlipidaemia. Oedema results from reduced oncotic pressure and sodium retention.

Question 16Chemical Pathology (Clinical Biochemistry)

Which enzyme pattern is most suggestive of cholestatic liver injury rather than hepatocellular injury?

  1. Alkaline phosphatase and gamma-glutamyl transferase raised out of proportion to aminotransferases Correct answer.
  2. Alanine aminotransferase raised out of proportion to alkaline phosphatase
  3. Isolated rise in serum amylase
  4. Isolated rise in creatine kinase

Explanation

Cholestasis induces alkaline phosphatase and gamma-glutamyl transferase on canalicular membranes, so these rise disproportionately. Aminotransferases predominate when hepatocytes themselves are injured.

Question 17Chemical Pathology (Clinical Biochemistry)

A 70-year-old man has a serum calcium of 3.1 mmol/L and a markedly raised PTH. Which additional finding would most strongly suggest parathyroid carcinoma rather than benign adenoma?

  1. A mildly raised PTH with mild hypercalcaemia
  2. A very high PTH with severe hypercalcaemia and a palpable neck mass Correct answer.
  3. A normal PTH with hypophosphataemia
  4. A suppressed PTH with hypercalcaemia

Explanation

Parathyroid carcinoma typically produces much higher calcium and PTH values than adenomas and may present with a palpable neck mass. Benign adenomas usually cause mild hypercalcaemia with modestly elevated PTH.

Question 18Chemical Pathology (Clinical Biochemistry)

Which laboratory finding is expected in a patient with untreated diabetic ketoacidosis?

  1. Normal anion gap with hyperchloraemia only
  2. Raised anion gap with reduced bicarbonate and raised beta-hydroxybutyrate Correct answer.
  3. Reduced anion gap with raised bicarbonate
  4. Raised bicarbonate with respiratory acidosis

Explanation

Ketone bodies are unmeasured anions, so the anion gap increases as bicarbonate is consumed in buffering. Beta-hydroxybutyrate is the predominant ketone and is measured directly in modern assays.

Question 19Chemical Pathology (Clinical Biochemistry)

A patient has a serum TSH of 0.02 mIU/L with a free T4 of 38 pmol/L (reference 10-22). Which explanation best fits this pattern?

  1. Central hypothyroidism
  2. Primary hypothyroidism
  3. Iodine deficiency
  4. Graves disease or another cause of thyrotoxicosis Correct answer.

Explanation

High free T4 with a suppressed TSH indicates thyrotoxicosis, in which thyroid hormone excess feeds back to inhibit pituitary TSH. Graves disease is a common cause, with stimulating TSH-receptor antibodies.

Question 20Chemical Pathology (Clinical Biochemistry)

Which analyte requires careful handling because its concentration in serum rises artefactually when glycolysis is not inhibited after collection?

  1. Creatinine
  2. Albumin
  3. Sodium
  4. Glucose Correct answer.

Explanation

Erythrocytes and leucocytes continue to consume glucose after collection, so tubes must contain fluoride or be processed promptly. Delayed separation lowers measured glucose and can cause a missed diagnosis of diabetes.

Question 21Chemical Pathology (Clinical Biochemistry)

A patient with a known monoclonal gammopathy has a serum sodium of 129 mmol/L measured by indirect ion-selective electrode. Which phenomenon most likely explains this?

  1. Pseudohyponatraemia from hyperproteinaemia Correct answer.
  2. True sodium depletion from vomiting
  3. Diabetes insipidus
  4. Hyperaldosteronism

Explanation

Very high protein or lipid concentrations displace the aqueous phase, so indirect ion-selective electrode methods report falsely low sodium. Direct ion-selective electrode or measurement of osmolality helps confirm pseudohyponatraemia.

Question 22Chemical Pathology (Clinical Biochemistry)

Which test is the most appropriate to confirm suspected vitamin B12 deficiency in a patient with macrocytic anaemia and neurological symptoms?

  1. Serum methylmalonic acid and homocysteine Correct answer.
  2. Serum iron
  3. Serum ferritin
  4. Serum folate only

Explanation

Methylmalonic acid and homocysteine rise early in vitamin B12 deficiency and are more sensitive than serum B12 alone. Methylmalonic acid is the more specific marker because it is not affected by folate deficiency.

Question 23Chemical Pathology (Clinical Biochemistry)

Which statement about troponin measurement in suspected acute coronary syndrome is most accurate?

  1. A single normal high-sensitivity troponin excludes myocardial infarction at presentation
  2. Troponin is specific for skeletal muscle injury
  3. Troponin rises only after 24 hours and remains elevated for one week
  4. Serial high-sensitivity troponin measurements with a delta value improve diagnostic accuracy Correct answer.

Explanation

High-sensitivity troponin assays detect very small rises early, and serial sampling with a delta value distinguishes acute myocardial injury from chronic elevation. A single value at presentation may be normal in early infarction.

Question 24Chemical Pathology (Clinical Biochemistry)

A patient with severe vomiting has a serum bicarbonate of 34 mmol/L and a pH of 7.50. Which acid-base disturbance is present?

  1. Metabolic alkalosis Correct answer.
  2. Normal acid-base status
  3. Respiratory acidosis
  4. Metabolic acidosis

Explanation

Vomiting loses gastric hydrogen and chloride, generating a metabolic alkalosis with a raised bicarbonate and alkaline pH. Compensation is hypoventilation, which raises PaCO2.

Question 25Chemical Pathology (Clinical Biochemistry)

In a patient with suspected primary hyperaldosteronism, which pattern of results is expected?

  1. Raised aldosterone with suppressed renin and hypokalaemia Correct answer.
  2. Raised aldosterone with raised renin and hyperkalaemia
  3. Low aldosterone with low renin
  4. Low aldosterone with raised renin

Explanation

Autonomous aldosterone secretion expands volume, suppresses renin and drives potassium excretion, producing hypertension with hypokalaemia. The aldosterone-to-renin ratio is the standard screening test.

Question 26Chemical Pathology (Clinical Biochemistry)

A fasting serum sample is left on the bench overnight before centrifugation. Which analyte is most likely to be falsely elevated compared with a promptly separated sample?

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

Explanation

Potassium is predominantly intracellular, so prolonged contact of serum with cells allows leakage across the red cell membrane and spurious hyperkalaemia. Prompt separation or use of a lithium heparin tube limits this pre-analytical error. Sodium, chloride and bicarbonate are largely extracellular and change much less.

Question 27Chemical Pathology (Clinical Biochemistry)

Which formula correctly describes the relationship used to calculate the anion gap in a routine electrolyte profile?

  1. (Sodium + chloride) minus (potassium + bicarbonate)
  2. (Chloride + bicarbonate) minus (sodium + potassium)
  3. (Sodium + potassium) minus (chloride + bicarbonate) Correct answer.
  4. (Sodium + bicarbonate) minus (chloride + potassium)

Explanation

The anion gap estimates unmeasured anions by subtracting the measured anions chloride and bicarbonate from the measured cations sodium and potassium. Some laboratories omit potassium, but the principle of cations minus anions is unchanged. It is used to classify metabolic acidosis into high-gap and normal-gap causes.

Question 28Chemical Pathology (Clinical Biochemistry)

A 58-year-old woman with type 2 diabetes has a fasting plasma glucose of 8.9 mmol/L. Which additional measurement is required before this sample can be used to diagnose diabetes mellitus?

  1. A 24-hour urinary glucose excretion
  2. A repeat confirmatory glucose measurement on another day Correct answer.
  3. A random plasma glucose during the same clinic visit
  4. A simultaneous serum insulin level

Explanation

In an asymptomatic patient, a single abnormal fasting glucose must be confirmed by repeat testing on a separate occasion, using the same or another standard test such as HbA1c. A single value in a symptomatic patient with classic hyperglycaemic symptoms can be diagnostic. Insulin and urinary glucose do not establish the diagnosis.

Question 29Chemical Pathology (Clinical Biochemistry)

Which laboratory finding is the most reliable indicator of adequate iron stores in a patient with chronic inflammation?

  1. Serum iron within the reference interval
  2. Mean corpuscular volume within the reference interval
  3. Transferrin saturation above 20%
  4. Serum ferritin within the reference interval Correct answer.

Explanation

Ferritin is the main storage protein and a normal ferritin makes iron deficiency unlikely even in inflammation, where ferritin behaves as an acute-phase reactant and may be raised. Serum iron and transferrin saturation fall in inflammation because of hepcidin-mediated sequestration, so they cannot exclude deficiency. MCV changes only late and is not a store marker.

Question 30Chemical Pathology (Clinical Biochemistry)

A 47-year-old man has a serum calcium of 2.95 mmol/L with a suppressed PTH. Which measurement is the most appropriate next step to identify the cause?

  1. Serum alkaline phosphatase
  2. Serum phosphate
  3. Serum parathyroid hormone-related peptide Correct answer.
  4. 24-hour urinary calcium

Explanation

Hypercalcaemia with a suppressed PTH points to a non-parathyroid cause, and malignancy is the commonest. PTH-related peptide mediates humoral hypercalcaemia of malignancy and directly identifies that mechanism. Phosphate, alkaline phosphatase and urinary calcium give supportive but non-specific information.

Question 31Chemical Pathology (Clinical Biochemistry)

A 30-year-old woman has a serum sodium of 118 mmol/L, serum osmolality of 250 mOsm/kg and urine osmolality of 620 mOsm/kg while clinically euvolaemic. Which diagnosis best fits this pattern?

  1. Primary polydipsia
  2. Diabetes insipidus
  3. Syndrome of inappropriate antidiuretic hormone secretion Correct answer.
  4. Osmotic diuresis from uncontrolled diabetes

Explanation

Hypo-osmolar, euvolaemic hyponatraemia with inappropriately concentrated urine indicates SIADH once thyroid and adrenal function are normal. The concentrated urine excludes primary polydipsia and diabetes insipidus, in which urine osmolality is low. Osmotic diuresis causes volume depletion with low urine osmolality relative to plasma.

Question 32Chemical Pathology (Clinical Biochemistry)

A 66-year-old man with known chronic kidney disease has a serum potassium of 6.4 mmol/L and a normal ECG. Which finding would most strongly suggest that the hyperkalaemia is spurious?

  1. A raised serum creatinine consistent with his known kidney disease
  2. A low serum bicarbonate of 19 mmol/L
  3. A normal serum potassium in a plasma sample collected without prolonged tourniquet use Correct answer.
  4. A mildly raised serum phosphate

Explanation

Spurious hyperkalaemia from haemolysis, prolonged tourniquet use or delayed separation is confirmed when a carefully collected plasma sample gives a normal result. The other findings are all expected consequences of chronic kidney disease and do not indicate artefact. Repeat sampling with attention to technique is the practical confirmatory step.

Question 33Chemical Pathology (Clinical Biochemistry)

A 24-year-old man has a serum sodium of 132 mmol/L, serum osmolality of 268 mOsm/kg and a markedly raised total protein with normal lipids. Which mechanism best explains the hyponatraemia?

  1. Hypertonic hyponatraemia from hyperglycaemia
  2. Pseudohyponatraemia from hyperproteinaemia Correct answer.
  3. Hyponatraemia from adrenal insufficiency
  4. True hypotonic hyponatraemia from water excess

Explanation

Marked hyperproteinaemia increases the non-aqueous fraction of plasma, so indirect ion-selective electrode methods report a falsely low sodium while measured osmolality remains normal. The normal osmolality excludes true hypotonic hyponatraemia. Direct ion-selective electrode measurement or measurement on a blood gas analyser confirms the artefact.

Question 34Chemical Pathology (Clinical Biochemistry)

A 52-year-old woman has a serum TSH of 6.8 mIU/L with a free T4 within the reference range on two occasions. Which interpretation is most appropriate?

  1. Euthyroid sick syndrome
  2. Subclinical hypothyroidism Correct answer.
  3. Overt primary hypothyroidism
  4. Central hypothyroidism

Explanation

Subclinical hypothyroidism is defined by a raised TSH with a free T4 that remains within the reference range. Overt hypothyroidism requires a low free T4 in addition. Central hypothyroidism would show a low or inappropriately normal TSH, and sick euthyroid syndrome is seen in acute illness.

Question 35Chemical Pathology (Clinical Biochemistry)

A 41-year-old man with a history of recurrent renal stones has a serum calcium of 2.72 mmol/L and a PTH of 11 pmol/L. Which additional finding would best support primary hyperparathyroidism rather than familial hypocalciuric hypercalcaemia?

  1. A 24-hour urinary calcium excretion within the reference range or high Correct answer.
  2. A serum magnesium of 0.85 mmol/L
  3. A low 24-hour urinary calcium excretion
  4. A family history of hypercalcaemia in a young relative

Explanation

Primary hyperparathyroidism usually produces normal or high urinary calcium, whereas familial hypocalciuric hypercalcaemia shows inappropriately low urinary calcium with a low calcium-to-creatinine clearance ratio. The urinary calcium excretion therefore helps discriminate the two. Magnesium and family history are supportive but not discriminating.

Question 36Chemical Pathology (Clinical Biochemistry)

A 68-year-old woman with a monoclonal gammopathy has a total protein of 104 g/L and an albumin of 30 g/L. Which calculation best estimates the globulin fraction?

  1. Total protein divided by albumin
  2. Total protein minus albumin Correct answer.
  3. Albumin minus total protein
  4. Total protein multiplied by albumin

Explanation

The globulin concentration is estimated by subtracting the albumin from the total protein, giving 74 g/L here, which is markedly raised and consistent with a paraprotein. The globulin fraction includes immunoglobulins and other transport proteins. A paraprotein is then characterised by serum electrophoresis and immunofixation.

Question 37Chemical Pathology (Clinical Biochemistry)

A 55-year-old man has a serum bicarbonate of 14 mmol/L, a pH of 7.28 and a raised anion gap. Which additional finding would most suggest a mixed high-gap and normal-gap metabolic acidosis?

  1. A chloride concentration lower than expected for the fall in bicarbonate
  2. A chloride concentration higher than expected for the fall in bicarbonate Correct answer.
  3. A raised serum potassium only
  4. A respiratory rate of 12 breaths per minute

Explanation

In a pure high-gap acidosis, the fall in bicarbonate is matched by a rise in unmeasured anions and chloride stays near normal. A chloride higher than predicted indicates coexisting normal-gap (hyperchloraemic) acidosis. A low chloride would suggest a mixed high-gap and metabolic alkalosis.

Question 38Chemical Pathology (Clinical Biochemistry)

A 62-year-old man with known cirrhosis has a serum sodium of 126 mmol/L and a serum osmolality of 262 mOsm/kg. Which laboratory finding would best support hypervolaemic hyponatraemia due to cirrhosis rather than SIADH?

  1. A low urine sodium with clinical ascites and oedema Correct answer.
  2. A high urine sodium with clinical euvolaemia
  3. A normal serum cortisol
  4. A low serum uric acid with normal thyroid function

Explanation

Cirrhosis activates the renin-angiotensin-aldosterone axis, so urine sodium is typically low and the patient is hypervolaemic with ascites or oedema. SIADH occurs in a euvolaemic patient with inappropriately high urine sodium. Uric acid and cortisol help exclude other causes but do not discriminate these two.

Question 39Chemical Pathology (Clinical Biochemistry)

A 35-year-old woman with a history of recurrent hypoglycaemia has a fasting glucose of 2.4 mmol/L, a raised insulin and a suppressed C-peptide. Which explanation best fits these results?

  1. Adrenal insufficiency
  2. Factitious hypoglycaemia from a sulfonylurea
  3. Exogenous insulin administration Correct answer.
  4. Insulinoma

Explanation

Exogenous insulin suppresses endogenous secretion, so C-peptide is low while immunoreactive insulin is high. In an insulinoma both insulin and C-peptide are raised. Sulfonylureas stimulate endogenous insulin release and therefore raise C-peptide, and adrenal insufficiency causes low insulin with low C-peptide.

Question 40Chemical Pathology (Clinical Biochemistry)

A 44-year-old man has a serum creatinine of 180 micromol/L and a 24-hour urinary creatinine excretion of 14 mmol. Which parameter is required to calculate his creatinine clearance?

  1. His urinary protein excretion
  2. His serum albumin
  3. A timed urine volume Correct answer.
  4. His body surface area only

Explanation

Creatinine clearance is calculated from urinary creatinine concentration multiplied by urine volume divided by serum creatinine and the collection time, so a timed volume is essential. Body surface area allows indexing of the result but does not permit the calculation itself. Albumin and protein excretion are unrelated to clearance calculation.

Question 41Haematology and Blood Transfusion Medicine

A 30-year-old woman has a haemoglobin of 8.5 g/dL, MCV 68 fL, and a peripheral smear showing hypochromic microcytic red cells with target cells. Serum ferritin is normal and haemoglobin electrophoresis shows an elevated HbA2. What is the most likely diagnosis?

  1. Beta-thalassaemia trait Correct answer.
  2. Anaemia of chronic disease
  3. Sideroblastic anaemia
  4. Iron deficiency anaemia

Explanation

A microcytic hypochromic picture with a normal ferritin and a raised HbA2 is the classic signature of beta-thalassaemia trait. Iron deficiency would lower ferritin, and the anaemia of chronic disease is usually normocytic with low iron and low TIBC.

Question 42Haematology and Blood Transfusion Medicine

Which laboratory finding is most characteristic of immune thrombocytopenia (ITP) in an otherwise healthy adult?

  1. Prolonged APTT with a normal platelet count
  2. Pancytopenia with hypocellular marrow
  3. Isolated thrombocytopenia with a normal peripheral blood film apart from reduced platelets Correct answer.
  4. Schistocytes with a raised LDH

Explanation

ITP is a diagnosis of exclusion characterised by isolated thrombocytopenia with otherwise normal blood counts and film. Marrow is cellular with increased megakaryocytes, and coagulation screen is normal.

Question 43Haematology and Blood Transfusion Medicine

A patient with acute myeloid leukaemia has a blast population that stains positive with myeloperoxidase and Sudan Black B. Which lineage does this confirm?

  1. Megakaryocytic
  2. Myeloid Correct answer.
  3. Lymphoid
  4. Erythroid

Explanation

Myeloperoxidase and Sudan Black B positivity indicate primary granules and therefore myeloid differentiation. Lymphoblasts are MPO negative, while erythroid and megakaryocytic blasts require other markers such as glycophorin A or CD41.

Question 44Haematology and Blood Transfusion Medicine

Which red cell index pattern is expected in a patient with combined iron deficiency and thalassaemia trait?

  1. Low MCV with a Mentzer index below 13 Correct answer.
  2. Low MCV with a Mentzer index above 13
  3. Raised MCV with normal MCH
  4. Macrocytosis with a raised reticulocyte count

Explanation

The Mentzer index (MCV divided by red cell count) below 13 favours thalassaemia, whereas values above 13 favour iron deficiency. In combined deficiency the microcytosis persists and the index often remains low.

Question 45Haematology and Blood Transfusion Medicine

A patient with chronic kidney disease has a normocytic normochromic anaemia with a low reticulocyte count. Which finding best supports inadequate erythropoietin production as the cause?

  1. Raised serum haptoglobin
  2. Raised reticulocyte count with polychromasia
  3. Positive direct antiglobulin test
  4. Low serum erythropoietin relative to the degree of anaemia Correct answer.

Explanation

In CKD the kidney fails to mount an appropriate erythropoietin response, so the level is low relative to the haemoglobin. A normal or high EPO in the face of anaemia would suggest other causes.

Question 46Haematology and Blood Transfusion Medicine

Which parameter on an automated analyser is most useful for detecting red cell fragmentation in a patient with suspected microangiopathy?

  1. Red cell distribution width Correct answer.
  2. Reticulocyte haemoglobin content
  3. Mean corpuscular haemoglobin concentration
  4. Red cell count

Explanation

Fragmentation produces anisocytosis, which widens the red cell distribution width. The RDW is a sensitive but non-specific indicator of a mixed red cell population such as schistocytes.

Question 47Haematology and Blood Transfusion Medicine

A patient with sickle cell disease presents with a haemoglobin of 5 g/dL, a reticulocyte count of 2%, and aplastic marrow. What is the most likely diagnosis?

  1. Acute splenic sequestration
  2. Parvovirus B19-induced aplastic crisis Correct answer.
  3. Acute chest syndrome
  4. Hyperhaemolytic transfusion reaction

Explanation

Parvovirus B19 infects erythroid progenitors and causes a transient red cell aplasia, so reticulocytes fall and haemoglobin drops sharply. Splenic sequestration causes a falling haemoglobin with a rising reticulocyte count and a large spleen.

Question 48Haematology and Blood Transfusion Medicine

Which finding on the blood film is most consistent with a diagnosis of hereditary spherocytosis?

  1. Numerous spherocytes with increased osmotic fragility Correct answer.
  2. Bite cells with Heinz bodies
  3. Target cells with an elevated HbA2
  4. Basophilic stippling with coarse granules

Explanation

Hereditary spherocytosis is caused by membrane protein defects leading to spherocytes that are osmotically fragile. The osmotic fragility test is increased and EMA binding is reduced.

Question 49Haematology and Blood Transfusion Medicine

A patient has a prolonged APTT that corrects with a 50:50 mix of normal plasma incubated for two hours. What is the most likely explanation?

  1. A factor VIII inhibitor
  2. Factor VIII deficiency Correct answer.
  3. Factor XIII deficiency
  4. A lupus anticoagulant

Explanation

A factor deficiency corrects on mixing because the missing factor is supplied by normal plasma. The two-hour incubation allows time-dependent inhibitors to act, so persistent prolongation would suggest an inhibitor.

Question 50Haematology and Blood Transfusion Medicine

Which laboratory finding is most consistent with disseminated intravascular coagulation?

  1. Prolonged PT and APTT with raised D-dimer and low fibrinogen Correct answer.
  2. Normal PT and APTT with a raised platelet count
  3. Isolated prolonged bleeding time with normal platelet count
  4. Prolonged PT with normal platelets and fibrinogen

Explanation

DIC consumes coagulation factors and platelets while activating fibrinolysis, so PT and APTT prolong, D-dimer rises and fibrinogen falls. Serial testing is usually needed to confirm the trend.