Hematology — MCQs

The parents of a 13-month-old boy are contacted by a local social agency because the day care reported them for suspected child abuse based on 'too many bruises.' The parents deny the abuse and promptly arrange to have their child seen by a medical specialist. The child has multiple large bruises on his legs, anus, and buttocks. No skin abrasions and no 'pattern marks' are seen. PTT is prolonged and PT and bleeding time are normal. Which of the following is the most probable diagnosis?

Q447Medium

Which of the following conditions is associated with raised levels of fetal hemoglobin (HbF)?

Q448Medium

All of the following are causes of sideroblastic anemia, except?

Q449Easy

Increased Prothrombin time results from a deficiency of which factor?

Q450Medium

Decreased osmotic fragility is seen in which of the following conditions?

Hematology Indian Medical PG Practice Questions and MCQs

Question 441: A couple with a family history of beta-thalassemia major in a distant relative has come for counseling. The husband has HbA2 of 4.8% and the wife has HbA2 of 2.3%. What is the risk of them having a child with beta-thalassemia major?

A. 50%
B. 25%
C. 5%
D. 0% (Correct Answer)

Explanation: ### Explanation **1. Understanding the Correct Answer (D: 0%)** To have a child with **Beta-Thalassemia Major**, both parents must be carriers (**Beta-Thalassemia Trait/Minor**). * **The Husband:** His HbA2 is **4.8%**. In clinical practice, an HbA2 level **>3.5%** is the diagnostic hallmark of Beta-Thalassemia Trait. Thus, the husband is a carrier. * **The Wife:** Her HbA2 is **2.3%**. The normal range for HbA2 is **1.5% to 3.5%**. Since her value is within the normal range, she is not a carrier of the beta-thalassemia gene. Beta-thalassemia is an **autosomal recessive** disorder. For a child to manifest the "Major" form ($β^0/β^0$ or $β^+/β^+$), they must inherit one defective gene from each parent. Since the wife is hematologically normal, she will always pass on a normal beta-globin gene. Therefore, the risk of having a child with Thalassemia Major is **0%**. (The risk of having a child with Thalassemia Trait is 50%). **2. Why Other Options are Incorrect** * **A (50%) & B (25%):** These probabilities would only apply if both parents were carriers. If both were carriers, the risk for Major would be 25% and for Trait would be 50%. * **C (5%):** This is a distractor with no genetic basis in Mendelian inheritance for this condition. **3. NEET-PG High-Yield Pearls** * **Gold Standard Diagnosis:** Hb electrophoresis or HPLC (High-Performance Liquid Chromatography). * **HbA2 Levels:** * Normal: 1.5–3.5% * β-Thalassemia Trait: >3.5% (usually 4–8%) * Iron Deficiency Anemia: Can falsely **lower** HbA2 levels, potentially masking a Thalassemia trait. * **Mentzer Index:** MCV/RBC count. If **<13**, it suggests Thalassemia; if **>13**, it suggests Iron Deficiency Anemia.

Question 442: What is the reliable initial screening test for hemochromatosis?

A. Liver biopsy
B. TIBC
C. Transferrin saturation (Correct Answer)
D. Mutation analysis

Explanation: **Explanation:** Hereditary Hemochromatosis (HH) is an autosomal recessive disorder characterized by excessive intestinal iron absorption leading to multiorgan deposition [2]. **Why Transferrin Saturation (TS) is the correct answer:** Transferrin saturation is the **most sensitive and reliable initial screening test**. It is calculated as (Serum Iron ÷ TIBC) × 100 [3]. A fasting TS value **>45%** is highly suggestive of iron overload. While Serum Ferritin is also used, it is an acute-phase reactant and can be falsely elevated in inflammation, malignancy, or liver disease [1], making TS the preferred first-line screening tool. **Analysis of Incorrect Options:** * **Liver Biopsy (A):** Historically the "gold standard," it is now reserved for staging fibrosis or when the diagnosis is unclear despite genetic testing [1]. It is invasive and never an initial screening test. * **TIBC (B):** Total Iron Binding Capacity is typically **decreased** in hemochromatosis. While it is used to calculate TS, it is not a standalone screening test. * **Mutation Analysis (D):** Testing for the **HFE gene (C282Y and H63D)** is the confirmatory test [1]. It is performed only after biochemical evidence of iron overload (elevated TS) is established. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Triad (Bronze Diabetes):** Cirrhosis, Diabetes Mellitus, and Skin Hyperpigmentation [2]. * **Most common cause of death:** Decompensated Cirrhosis (though Hepatocellular Carcinoma risk is significantly increased) [2]. * **Arthropathy:** Characteristically involves the 2nd and 3rd metacarpophalangeal (MCP) joints with "hook-like" osteophytes. * **Treatment of choice:** Therapeutic Phlebotomy (Goal: Ferritin <50 ng/mL) [1].

Question 443: Which of the following does not cause sideroblastic anemia?

A. Isoniazid (INH)
B. Chloramphenicol
C. Myelodysplastic syndrome
D. Mercury (Correct Answer)

Explanation: **Explanation:** **Sideroblastic anemia** is characterized by the failure of iron to incorporate into the heme molecule, despite adequate iron stores. This leads to the formation of **ringed sideroblasts** in the bone marrow (erythroblasts with iron-laden mitochondria encircling the nucleus). **Why Mercury is the Correct Answer:** Mercury poisoning typically presents with neurological symptoms (tremors, erethism) and renal damage [2], but it is **not** a recognized cause of sideroblastic anemia. In contrast, **Lead** is the heavy metal classically associated with this condition because it inhibits ferrochelatase and ALA dehydratase [3]. **Analysis of Other Options:** * **Isoniazid (INH):** This is a classic cause. INH is a Vitamin B6 (pyridoxine) antagonist. Since Vitamin B6 is a required cofactor for ALA synthase (the rate-limiting enzyme in heme synthesis), its deficiency leads to sideroblastic changes. * **Chloramphenicol:** This antibiotic can cause reversible sideroblastic anemia by interfering with mitochondrial protein synthesis, which disrupts the mitochondrial function necessary for heme production. * **Myelodysplastic Syndrome (MDS):** This is the most common **acquired/clonal** cause. Specifically, the subtype Refractory Anemia with Ringed Sideroblasts (RARS) is characterized by mutations (often in the *SF3B1* gene) that lead to ineffective erythropoiesis and ringed sideroblasts. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard Investigation:** Bone marrow examination with **Perl’s Prussian Blue stain** to visualize ringed sideroblasts. * **Classic Finding:** Dimorphic blood picture (a mix of normocytic and microcytic hypochromic cells) on peripheral smear [1]. * **Treatment:** For INH-induced or hereditary cases, trial of **Pyridoxine (Vitamin B6)** is the first line. * **Other Causes:** Alcohol (most common cause of acquired non-clonal), Zinc toxicity (causes copper deficiency), and Copper deficiency.

Question 444: Which of the following is NOT a congenital cause of hypercoagulable states?

A. Protein C deficiency
B. Protein S deficiency
C. MTHFR mutation
D. Lupus anticoagulant (Correct Answer)

Explanation: The core of this question lies in distinguishing between **inherited (congenital)** and **acquired** thrombophilias. **1. Why Lupus Anticoagulant is the correct answer:** Lupus anticoagulant (LA) is an **acquired** hypercoagulable state. It is one of the three major antibodies found in **Antiphospholipid Antibody Syndrome (APS)**. Despite its name, it is a pro-thrombotic agent *in vivo*, leading to arterial and venous thrombosis, as well as recurrent pregnancy loss. It is not a genetic mutation passed down through germlines but rather an autoimmune phenomenon often associated with Systemic Lupus Erythematosus (SLE) or occurring idiopathically. **2. Why the other options are incorrect:** * **Protein C and Protein S Deficiency:** These are classic **inherited** autosomal dominant conditions [1]. These proteins are natural anticoagulants that degrade Factors Va and VIIIa [1]. Their deficiency leads to an unchecked coagulation cascade. * **MTHFR Mutation:** The Methylenetetrahydrofolate reductase (MTHFR) gene mutation is a **congenital** genetic variation. It can lead to hyperhomocysteinemia, which is a recognized risk factor for thrombosis (though its clinical significance is currently debated compared to Factor V Leiden). **High-Yield Clinical Pearls for NEET-PG:** * **Most common inherited cause of thrombophilia:** Factor V Leiden (Activated Protein C resistance). * **Most common acquired cause of thrombophilia:** Antiphospholipid Antibody Syndrome (APS). * **Warfarin-induced skin necrosis:** Classically seen in patients with **Protein C deficiency** when starting Warfarin without a heparin bridge. * **Paradoxical Lab Finding:** Lupus anticoagulant causes a **prolonged aPTT** *in vitro*, but causes **thrombosis** *in vivo*.

Question 445: Cold agglutinins are seen in which of the following conditions?

A. Influenza (Correct Answer)
B. Polyarteritis nodosa (PAN)
C. Multiple myeloma
D. Systemic lupus erythematosus (SLE)

Explanation: **Explanation:** Cold agglutinins are autoantibodies (usually **IgM**) that bind to the 'I' or 'i' antigens on the surface of red blood cells at low temperatures (typically <30°C), leading to agglutination and extravascular hemolysis [1]. **1. Why Influenza is correct:** Cold agglutinin disease is frequently secondary to specific infections. The most common triggers are ***Mycoplasma pneumoniae*** (associated with anti-I antibodies) and viral infections like **Infectious Mononucleosis (EBV)**, **Cytomegalovirus (CMV)**, and **Influenza** [2]. These pathogens can trigger a transient, polyclonal IgM response that cross-reacts with RBC antigens [2]. **2. Why the other options are incorrect:** * **Polyarteritis nodosa (PAN):** This is a systemic necrotizing vasculitis of medium-sized arteries. It is classically associated with Hepatitis B, but not with cold agglutinins. * **Multiple myeloma:** This is a plasma cell dyscrasia characterized by IgG or IgA monoclonal spikes. While it can cause anemia of chronic disease or hyperviscosity, it is not a typical cause of cold agglutinins. * **Systemic lupus erythematosus (SLE):** SLE is the classic cause of **Warm Autoimmune Hemolytic Anemia (WAIHA)**, mediated by **IgG** antibodies that react at body temperature (37°C) [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Warm AIHA:** IgG; associated with SLE, CLL, and drugs (α-methyldopa) [1]. * **Cold AIHA:** IgM; associated with *Mycoplasma*, EBV, and Lymphoma [2]. * **Blood Smear:** Look for **RBC clumps/agglutination** (unlike Rouleaux, which is linear) [2]. * **Direct Coombs Test:** In Cold AIHA, the test is positive for **C3d** (complement) but negative for IgG [1].

Question 446: The parents of a 13-month-old boy are contacted by a local social agency because the day care reported them for suspected child abuse based on 'too many bruises.' The parents deny the abuse and promptly arrange to have their child seen by a medical specialist. The child has multiple large bruises on his legs, anus, and buttocks. No skin abrasions and no 'pattern marks' are seen. PTT is prolonged and PT and bleeding time are normal. Which of the following is the most probable diagnosis?

A. Acute myelogenous leukemia
B. Disseminated intravascular coagulation
C. Vitamin K deficiency
D. Von Willebrand disease (Correct Answer)

Explanation: The clinical presentation of easy bruising in a toddler, often mistaken for child abuse, is a classic scenario for inherited bleeding disorders [1]. The key to this diagnosis lies in the coagulation profile: **Prolonged PTT** with **Normal PT and Bleeding Time**. **Why Von Willebrand Disease (vWD) is correct:** Von Willebrand Factor (vWF) serves two primary roles: it facilitates platelet adhesion to subendothelial collagen [2] and acts as a carrier protein to stabilize **Factor VIII**. In certain subtypes of vWD (particularly Type 1 or 2N), the deficiency of vWF leads to a secondary decrease in Factor VIII levels. Since Factor VIII is part of the intrinsic pathway, its deficiency results in a **prolonged PTT**. While vWD usually prolongs bleeding time (BT), BT can be normal in mild cases or specific variants [1], making vWD the most plausible diagnosis among the choices provided for a child with isolated PTT elevation and bruising. **Why other options are incorrect:** * **Acute Myelogenous Leukemia (AML):** Would typically present with systemic symptoms (fever, weight loss), hepatosplenomegaly, and pancytopenia (thrombocytopenia would prolong BT). * **Disseminated Intravascular Coagulation (DIC):** This is an acute, consumptive coagulopathy. Both PT and PTT would be prolonged, and the child would appear critically ill. * **Vitamin K Deficiency:** Affects Factors II, VII, IX, and X. Since Factor VII has the shortest half-life, the **PT is prolonged first** and more significantly than the PTT. **NEET-PG High-Yield Pearls:** * **Most common inherited bleeding disorder:** Von Willebrand Disease. * **vWF Function:** Platelet-to-collagen adhesion (via GpIb receptor) and stabilization of Factor VIII [2]. * **Ristocetin Cofactor Assay:** The gold standard diagnostic test for vWF activity (measures platelet agglutination). * **Treatment of choice:** Desmopressin (DDAVP), which releases stored vWF from Weibel-Palade bodies in endothelial cells [3].

Question 447: Which of the following conditions is associated with raised levels of fetal hemoglobin (HbF)?

A. Juvenile chronic myeloid leukemia (CML) (Correct Answer)
B. Hereditary spherocytosis
C. Congenital red cell aplasia
D. Myasthenia gravis

Explanation: ### Explanation **Correct Option: A. Juvenile chronic myeloid leukemia (CML)** Juvenile Myelomonocytic Leukemia (JMML)—historically referred to as Juvenile CML—is a rare clonal hematopoietic stem cell disorder of childhood. A hallmark diagnostic feature of JMML is a **markedly elevated fetal hemoglobin (HbF)** level, disproportionate for the child's age. This occurs because the malignant clone undergoes "fetal-like" erythropoiesis, reverting to the production of gamma-globin chains. In nearly 60–70% of cases, HbF levels are significantly raised (often >10–15%). **Analysis of Incorrect Options:** * **B. Hereditary Spherocytosis:** This is a red cell membrane defect (e.g., spectrin/ankyrin deficiency) leading to extravascular hemolysis. It does not involve a switch in globin chain synthesis; therefore, HbF levels remain normal. * **C. Congenital Red Cell Aplasia (Diamond-Blackfan Anemia):** While some patients with DBA can show an increase in HbF as a sign of "stress erythropoiesis," it is not the classic diagnostic association compared to the dramatic elevations seen in JMML. (Note: In some contexts, DBA is associated with raised HbF, but JMML remains the "textbook" association for this specific question type in hemat-oncology). * **D. Myasthenia Gravis:** This is an autoimmune neuromuscular junction disorder caused by antibodies against acetylcholine receptors. It has no primary hematological involvement or effect on hemoglobin synthesis. **High-Yield Clinical Pearls for NEET-PG:** * **JMML Triad:** Splenomegaly, skin rash (xanthomas/cafe-au-lait spots), and absence of the Philadelphia chromosome (t:9,22). * **Differential:** Unlike adult CML, JMML is **Philadelphia chromosome-negative**. * **Other causes of raised HbF:** Beta-thalassemia major, Sickle cell anemia, Hereditary Persistence of Fetal Hemoglobin (HPFH), and Aplastic anemia (during recovery). * **Drug-induced HbF:** Hydroxyurea is used in Sickle cell disease specifically because it increases HbF levels, which inhibits the polymerization of HbS [1].

Question 448: All of the following are causes of sideroblastic anemia, except?

A. Collagen vascular disease
B. Iron deficiency (Correct Answer)
C. Lead poisoning
D. Cutaneous porphyria

Explanation: Sideroblastic anemia is a group of disorders characterized by the body's inability to incorporate iron into hemoglobin, despite having adequate iron stores. This results in the formation of **ringed sideroblasts** (erythroblasts with iron-loaded mitochondria surrounding the nucleus). **Why Iron Deficiency is the correct answer:** In **Iron Deficiency Anemia (IDA)**, there is a systemic lack of iron [1], [3]. Therefore, the mitochondria cannot be overloaded with iron, and ringed sideroblasts cannot form. In fact, IDA is the polar opposite of sideroblastic anemia regarding iron status: IDA shows low serum iron and low ferritin, while sideroblastic anemia typically shows **high serum iron and high ferritin** [2]. **Analysis of Incorrect Options:** * **Lead Poisoning:** Lead inhibits two key enzymes in the heme synthesis pathway: *delta-aminolevulinic acid dehydratase (ALAD)* and *ferrochelatase*. This blockage leads to iron accumulation in mitochondria, causing sideroblastic changes. * **Cutaneous Porphyria (Porphyria Cutanea Tarda):** Porphyrias involve defects in heme synthesis. Disruptions in this pathway frequently lead to secondary iron overload and can manifest with sideroblastic features. * **Collagen Vascular Disease:** Chronic inflammatory states (like RA or SLE) can occasionally be associated with acquired sideroblastic anemia, often as part of a myelodysplastic syndrome (MDS) [2] or due to drugs used in their treatment (e.g., penicillamine). **High-Yield Clinical Pearls for NEET-PG:** 1. **Gold Standard Stain:** Prussian Blue (Perl’s) stain is used to visualize ringed sideroblasts in the bone marrow. 2. **Commonest Reversible Cause:** Alcoholism (it acts as a mitochondrial toxin). 3. **Drug-Induced:** Isoniazid (INH) causes it by interfering with Vitamin B6 (Pyridoxine) metabolism, which is a cofactor for ALA synthase. 4. **Genetic Cause:** X-linked sideroblastic anemia is most commonly due to a mutation in the *ALAS2* gene.

Question 449: Increased Prothrombin time results from a deficiency of which factor?

A. Factor IX
B. Fibrinogen (Correct Answer)
C. Factor VI
D. Factor XI

Explanation: **Explanation:** Prothrombin Time (PT) measures the integrity of the **Extrinsic** and **Common pathways** of the coagulation cascade [1]. The factors involved in these pathways are Factors **I (Fibrinogen)**, **II (Prothrombin)**, **V**, **VII**, and **X** [1]. 1. **Why Fibrinogen is correct:** Fibrinogen (Factor I) is the final substrate in the common pathway [2]. It is converted into fibrin to form a stable clot. Since PT monitors the common pathway, a significant deficiency in Fibrinogen (<100 mg/dL) will lead to a prolonged PT [1]. 2. **Why the others are incorrect:** * **Factor IX and Factor XI:** These are components of the **Intrinsic pathway** [1]. Deficiencies in these factors (e.g., Hemophilia B for Factor IX) will prolong the **Activated Partial Thromboplastin Time (aPTT)**, but the PT will remain normal. * **Factor VI:** This is a historical term. There is no "Factor VI" in the modern coagulation cascade (it was originally thought to be activated Factor V). **High-Yield Clinical Pearls for NEET-PG:** * **PT** is the most sensitive marker for **Vitamin K deficiency** and **Warfarin therapy** because it measures Factor VII, which has the shortest half-life (approx. 6 hours) [3]. * **Isolated prolonged PT:** Suggests Factor VII deficiency or early liver disease. * **Prolonged PT and aPTT:** Suggests a deficiency in the **Common Pathway** (Factors I, II, V, X) or severe Vitamin K deficiency/liver failure [1]. * **Mixing Study:** If PT/aPTT corrects with normal plasma, it indicates a **factor deficiency**; if it does not correct, it indicates the presence of an **inhibitor** (e.g., Lupus anticoagulant) [1].

Question 450: Decreased osmotic fragility is seen in which of the following conditions?

A. Hereditary spherocytosis
B. Sickle cell disease
C. Autoimmune hemolytic anemia
D. Thalassemia (Correct Answer)

Explanation: Osmotic fragility refers to the susceptibility of red blood cells (RBCs) to lysis when exposed to hypotonic solutions. This property depends primarily on the **surface area-to-volume ratio** of the cell. **Why Thalassemia is Correct:** In Thalassemia, there is a defect in globin chain synthesis, leading to "hypochromic microcytic" cells [1], [2]. These cells are thin and flat (leptocytes/target cells), which gives them a **high surface area-to-volume ratio**. Because they have "excess" membrane relative to their volume, they can absorb more water and swell significantly before the membrane stretches to the point of rupture. Thus, they are more resistant to lysis, resulting in **decreased osmotic fragility**. **Analysis of Incorrect Options:** * **Hereditary Spherocytosis (A):** This is the classic condition where osmotic fragility is **increased**. Molecular defects in membrane proteins (Ankyrin/Spectrin) cause the cell to lose membrane, resulting in a spherical shape with a **low surface area-to-volume ratio**. These cells cannot tolerate any swelling and burst easily. * **Autoimmune Hemolytic Anemia (C):** Similar to spherocytosis, partial phagocytosis of antibody-coated RBCs by splenic macrophages creates **spherocytes**, leading to **increased** osmotic fragility [4]. * **Sickle Cell Disease (B):** While sickle cells can sometimes show decreased fragility due to target cell formation, **Thalassemia** is the more classic and definitive answer for this question in the context of NEET-PG [3]. (Note: Dehydrated sickle cells may show variable results, but Thalassemia is the hallmark for decreased fragility). **NEET-PG High-Yield Pearls:** * **Increased Osmotic Fragility:** Hereditary Spherocytosis, AIHA, Hypernatremia. * **Decreased Osmotic Fragility:** Thalassemia (most common), Iron Deficiency Anemia (IDA), Sickle Cell Anemia, Liver Disease (Target cells). * **Confirmatory Test:** The **Incubated Osmotic Fragility Test** is the gold standard for diagnosing Hereditary Spherocytosis.

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Hematology — MCQs

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