AIM • EXAM REASONING

Question:

A 19-year-old man with chronic hemolytic anemia has jaundice, splenomegaly and numerous spherocytes. Direct antiglobulin testing is negative. Which additional red-cell index would most support the suspected membrane disorder?

Options:

Correct Answer:
Raised mean corpuscular hemoglobin concentration

Explanation: Membrane loss in hereditary spherocytosis reduces RBC surface area while intracellular hemoglobin is relatively preserved, so MCHC may increase.

Question:

A 23-year-old woman with a longstanding inherited spherocytic anemia develops recurrent right upper abdominal pain. Ultrasonography demonstrates gallstones. Which process most directly contributes to their formation?

Options:

Correct Answer:
Increased bilirubin production from erythrocyte breakdown

Explanation: Chronic extravascular hemolysis increases bilirubin production and predisposes to pigment gallstone formation.

Question:

Red cells from a teenager with sickle cell anemia initially regain their normal shape after reoxygenation. After repeated episodes, some cells remain permanently distorted. What best explains this progression?

Options:

Correct Answer:
Repeated sickling cycles causing membrane injury

Explanation: Early sickling may reverse with oxygenation, but repeated HbS polymerization damages the RBC membrane and eventually produces irreversibly sickled cells.

Question:

A 16-year-old boy with sickle cell anemia has chronic anemia and a high reticulocyte count. His blood film shows marked polychromasia. Which process accounts for this appearance?

Options:

Correct Answer:
Accelerated marrow release of reticulocytes

Explanation: Chronic hemolysis stimulates erythropoiesis; increased release of young reticulocytes produces polychromasia on the peripheral smear.

Question:

An 18-year-old man with sickle cell disease presents with sudden severe pain in his arms and legs. There is no history of trauma, and examination reveals diffuse tenderness without joint swelling. Which pathological event most directly produces the pain?

Options:

Correct Answer:
Obstruction of small vessels by rigid sickled erythrocytes

Explanation: Rigid sickled cells obstruct the microcirculation, causing tissue ischemia and the characteristic painful vaso-occlusive episode.

Question:

Genetic testing in a child with β-thalassemia identifies a mutation that permits production of a reduced amount of β-globin from the affected gene. Which designation best describes this allele?

Options:

Correct Answer:
β⁺ thalassemia allele

Explanation: A β⁺ mutation permits some β-globin synthesis, whereas a β⁰ mutation results in absent production from the affected gene.

Question:

A 21-year-old woman has hemoglobin 10.8 g/dL, MCV 62 fL and normal iron stores. Which additional CBC pattern would further favor a thalassemia trait over iron-deficiency anemia?

Options:

Correct Answer:
Relatively preserved erythrocyte count despite microcytosis

Explanation: Thalassemia trait may produce marked microcytosis despite a relatively preserved RBC count, helping distinguish it from iron deficiency.

Question:

A child with severe β-thalassemia has marked microcytosis, target cells, polychromasia and several nucleated RBCs in peripheral blood. What does the presence of nucleated RBCs most strongly indicate?

Options:

Correct Answer:
Marked erythropoietic stress with premature cell release

Explanation: Severe anemia strongly stimulates erythropoiesis, allowing immature nucleated erythroid cells to enter the peripheral circulation.

Question:

A child with severe β-thalassemia develops progressive iron accumulation despite having received relatively few transfusions. Which disease-related process can contribute to this finding?

Options:

Correct Answer:
Increased intestinal iron absorption associated with ineffective erythropoiesis

Explanation: Severe ineffective erythropoiesis increases the body’s drive to acquire iron, so intestinal absorption can contribute to iron loading even apart from transfusions.

Question:

Hemoglobin analysis is performed in a child with severe β-chain deficiency. Compared with normal adult blood, which change is expected because normal β-chain production is markedly reduced?

Options:

Correct Answer:
Greater proportion of fetal hemoglobin

Explanation: Marked β-chain deficiency reduces HbA formation, so severe β-thalassemia shows increased reliance on HbF.

Question:

A 10-year-old child with transfusion-dependent thalassemia is receiving regular packed-cell transfusions. Follow-up shows progressive iron accumulation. Which management principle most directly addresses this complication?

Options:

Correct Answer:
Instituting appropriate iron-chelation therapy

Explanation: Regular transfusions add iron that cannot be physiologically excreted; chelation is used to limit progressive iron-related organ injury.

Question:

A 20-year-old man has normal hemoglobin between episodes but develops abrupt hemolysis after eating fava beans. Which clinical pattern of G6PD deficiency best fits his presentation?

Options:

Correct Answer:
Episodic oxidant-triggered hemolysis

Explanation: Many G6PD-deficient patients remain well between attacks and develop hemolysis only when oxidative stress exceeds RBC antioxidant capacity.

Question:

A patient develops hemolysis after oxidative stress. Routine peripheral smear shows bite cells, and the laboratory wants to demonstrate the intracellular precipitates responsible for their formation. Which method is most appropriate?

Options:

Correct Answer:
Supravital staining of erythrocytes

Explanation: Heinz bodies are precipitated denatured hemoglobin and are demonstrated using an appropriate supravital stain rather than a routine smear alone.

Question:

Red cells from a patient with G6PD deficiency cannot adequately neutralize reactive oxygen species during an oxidative challenge. Failure to maintain which protective molecule in its active form is most directly responsible?

Options:

Correct Answer:
Reduced glutathione

Explanation: G6PD-generated NADPH keeps glutathione reduced; reduced glutathione protects hemoglobin and the RBC membrane from oxidative damage.

Question:

A 34-year-old man has episodic hemoglobinuria. His erythrocytes lack CD55 and CD59. Which consequence of this surface-protein defect most directly produces hemolysis?

Options:

Correct Answer:
Uncontrolled complement-mediated membrane injury

Explanation: CD55 and CD59 normally protect blood cells from complement; their loss leaves PNH erythrocytes vulnerable to intravascular complement attack.

Question:

A patient with unexplained hemolysis is investigated for PNH. The laboratory uses a fluorescent reagent that binds directly to normal GPI anchors and identifies a deficient cell population. Which investigation is being performed?

Options:

Correct Answer:
FLAER-based flow cytometric analysis

Explanation: FLAER binds GPI anchors; reduced binding on a cell population helps demonstrate the characteristic GPI-anchor deficiency of PNH.

Question:

A 40-year-old patient has flow-cytometry-confirmed PNH but reports episodes of hemolysis during both daytime and nighttime. Which interpretation is most appropriate?

Options:

Correct Answer:
PNH hemolysis may occur outside nighttime periods

Explanation: Despite its historical name, clinically important complement-mediated hemolysis in PNH is not restricted to nighttime.

Question:

A woman with hemolytic anemia has a direct antiglobulin test showing immunoglobulin attached to her erythrocytes. Hemolysis is predominantly splenic and occurs efficiently at body temperature. Which laboratory pattern best fits this mechanism?

Options:

Correct Answer:
IgG with or without complement on RBCs

Explanation: Warm autoimmune hemolysis is characteristically IgG-mediated; the DAT may demonstrate IgG alone or IgG together with complement.

Question:

A patient develops hemolytic anemia after exposure to a medication. The direct antiglobulin test supports an immune mechanism, and there was no transfusion or evidence of an inherited RBC disorder. How should this condition be classified?

Options:

Correct Answer:
Drug-associated immune hemolytic anemia

Explanation: Immune hemolysis temporally associated with medication exposure is classified as drug-associated immune hemolytic anemia.

Question:

A patient with hemolytic anemia has erythrocyte agglutination in a cool blood sample. Direct antiglobulin testing demonstrates complement on RBCs without significant IgG coating. Which immune mechanism best fits this pattern?

Options:

Correct Answer:
Cold-antibody complement-mediated hemolysis

Explanation: Cold-reactive IgM efficiently activates complement; after IgM dissociates in warmer blood, complement may remain detectable on the RBC surface.