Hematology — MCQs

Hematology Indian Medical PG Practice Questions and MCQs

Question 721: Basophilic stippling in RBCs is due to which enzyme deficiency?

A. Pyruvate kinase
B. G6PD
C. Glutathione synthase
D. Pyrimidine 5 nucleotidase (Correct Answer)

Explanation: **Explanation:** **Basophilic stippling** refers to the presence of numerous blue granules (ribosomal RNA precipitates) distributed throughout the cytoplasm of the Red Blood Cell (RBC) [3]. **Why Pyrimidine 5' Nucleotidase (P5N) is the correct answer:** Under normal physiological conditions, during the maturation of a reticulocyte into an erythrocyte, the enzyme **Pyrimidine 5' Nucleotidase** is responsible for the degradation and clearance of residual ribosomal RNA (rRNA). If this enzyme is deficient (either due to a rare congenital defect or acquired inhibition by **Lead poisoning**), pyrimidine nucleotides accumulate. This leads to the persistence and aggregation of ribosomal RNA, which manifests morphologically as coarse basophilic stippling on a peripheral blood smear [1]. **Analysis of Incorrect Options:** * **A. Pyruvate Kinase (PK):** Deficiency leads to chronic non-spherocytic hemolytic anemia. Morphologically, it is characterized by **echinocytes** (burr cells), not basophilic stippling. * **B. G6PD:** Deficiency leads to episodic hemolysis under oxidative stress [2]. Key findings include **Heinz bodies** (denatured hemoglobin) and **Bite cells** (degmacytes). * **C. Glutathione Synthase:** This is a rare defect in the ̳-glutamyl cycle causing mild hemolysis and neurological symptoms; it does not typically present with basophilic stippling. **High-Yield Clinical Pearls for NEET-PG:** * **Coarse Basophilic Stippling:** Think of two main conditions: **Lead Poisoning** (Plumbism) and **P5N Deficiency** [3]. * **Fine Basophilic Stippling:** Often seen in various anemias like Sideroblastic anemia, Thalassemia, and Megaloblastic anemia. * **Lead Poisoning Mechanism:** Lead directly inhibits the P5N enzyme, making basophilic stippling a classic diagnostic hallmark of lead toxicity [1].

Question 722: Decreased RBC production is seen in which of the following conditions?

A. Intramuscular folate administration
B. Renal failure (Correct Answer)
C. Post gastrectomy
D. Prosthetic valve hemolysis

Explanation: The correct answer is **Renal failure**. The primary mechanism behind decreased RBC production in chronic kidney disease (CKD) is the deficiency of **Erythropoietin (EPO)** [1]. EPO is a glycoprotein hormone produced by the peritubular interstitial cells of the renal cortex in response to hypoxia [1]. In renal failure, the loss of functional renal parenchyma leads to inadequate EPO production, resulting in a normocytic, normochromic anemia [1]. **Analysis of Options:** * **A. Intramuscular folate administration:** This would actually **increase** RBC production. Folate is essential for DNA synthesis; administering it to a deficient patient corrects megaloblastic maturation and stimulates erythropoiesis. * **C. Post gastrectomy:** This typically leads to anemia due to **increased loss or malabsorption** (Vitamin B12 deficiency due to loss of intrinsic factor and Iron deficiency due to loss of gastric acid) [2]. While it affects production eventually, it is classified primarily as a nutritional deficiency/malabsorption state rather than a primary failure of the bone marrow's production signal. * **D. Prosthetic valve hemolysis:** This is a classic example of **increased RBC destruction** (extravascular/mechanical hemolysis). The bone marrow is actually hyperactive in this condition, trying to compensate by increasing RBC production (reticulocytosis). **NEET-PG High-Yield Pearls:** * **Anemia of CKD:** Usually develops when GFR falls below **30-45 mL/min**. * **Target Hemoglobin:** When treating CKD patients with recombinant EPO, the target Hb is generally **10–11.5 g/dL**. Exceeding 13 g/dL increases the risk of cardiovascular events and thrombosis [1]. * **Echistocytes:** Always look for fragmented RBCs (schistocytes) on a peripheral smear in cases of prosthetic valve hemolysis (Microangiopathic Hemolytic Anemia).

Question 723: A pregnant patient in the second trimester has a hemoglobin level of 6 mg%. While IV transfusion of packed red cells was suggested, it is known that anemia can manifest as all of the following, except:

A. Headache
B. Vertigo
C. Delirium (Correct Answer)
D. Tinnitus

Explanation: **Explanation:** Anemia is characterized by a decrease in the oxygen-carrying capacity of the blood, leading to tissue hypoxia. The clinical manifestations of anemia are primarily due to compensatory mechanisms (tachycardia, increased cardiac output) and the direct effects of hypoxia on various organ systems, particularly the central nervous system (CNS). **1. Why Delirium is the Correct Answer:** Delirium is an acute, fluctuating syndrome of altered consciousness and cognitive dysfunction. While severe, acute hypoxia or metabolic disturbances can cause delirium, it is **not** a standard clinical manifestation of chronic or pregnancy-related anemia. Delirium typically suggests an underlying acute infection, drug toxicity, or severe metabolic derangement rather than simple low hemoglobin levels. **2. Analysis of Incorrect Options:** * **Headache:** This is a very common symptom of anemia. Hypoxia leads to compensatory cerebral vasodilation to maintain oxygen delivery to the brain, which can trigger headaches [1]. * **Vertigo:** Reduced oxygen delivery to the vestibular system and the brainstem can result in dizziness or vertigo [1]. * **Tinnitus:** Anemia causes a hyperdynamic circulatory state (increased blood flow velocity). This can lead to "pulsatile tinnitus," where the patient hears the sound of their own blood flow. **Clinical Pearls for NEET-PG:** * **WHO Definition of Anemia in Pregnancy:** Hb < 11 g/dL in the 1st and 3rd trimesters; < 10.5 g/dL in the 2nd trimester. * **Severe Anemia:** Defined as Hb < 7 g/dL. This patient (Hb 6 mg%) has severe anemia requiring urgent intervention. * **CNS Symptoms of Anemia:** Common symptoms include irritability, lack of concentration, faintness, and "roaring in the ears" (tinnitus). * **Hyperdynamic State:** Look for signs like a loud S1, hemic murmurs (systolic ejection murmurs), and a wide pulse pressure.

Question 724: What is the leading cause of death in Chronic Lymphocytic Leukemia (CLL)?

A. Infections (Correct Answer)
B. Bleeding
C. Meningeal and ventricular extension
D. Disseminated Intravascular Coagulation (DIC)

Explanation: **Explanation:** **1. Why Infections are the Leading Cause of Death:** In Chronic Lymphocytic Leukemia (CLL), the primary cause of mortality (responsible for 50-60% of deaths) is **infection** [1]. This susceptibility arises from a profound state of immune dysregulation characterized by: * **Hypogammaglobulinemia:** Progressive decline in serum immunoglobulin levels (IgG, IgA, and IgM) due to the suppression of normal B-cell function [1]. * **T-cell Dysfunction:** Impaired cell-mediated immunity, increasing the risk of viral (e.g., Herpes Zoster) and opportunistic infections. * **Neutropenia:** Often a result of advanced bone marrow infiltration or chemotherapy (e.g., Fludarabine). Common sites include the respiratory tract (pneumonia) and skin. **2. Why Other Options are Incorrect:** * **B. Bleeding:** While thrombocytopenia can occur due to marrow replacement or ITP (Evans Syndrome), it is a less frequent cause of death compared to sepsis [1]. * **C. Meningeal extension:** Central Nervous System (CNS) involvement is extremely rare in CLL. This is more characteristic of Acute Lymphoblastic Leukemia (ALL) or high-grade lymphomas. * **D. DIC:** Disseminated Intravascular Coagulation is a classic complication of **Acute Promyelocytic Leukemia (APL - M3)**, not CLL. **3. High-Yield Clinical Pearls for NEET-PG:** * **Richter’s Transformation:** In 3-10% of cases, CLL transforms into an aggressive **Diffuse Large B-Cell Lymphoma (DLBCL)**, marked by sudden clinical deterioration and rising LDH. * **Autoimmune Complications:** CLL is associated with **Autoimmune Hemolytic Anemia (AIHA)** and ITP [1]. * **Smudge Cells:** A classic peripheral smear finding (crushed lymphocytes). * **Staging:** Remember the **Rai** (USA) and **Binet** (Europe) staging systems for exam questions.

Question 725: Which of the following can be associated with paraproteinemias?

A. Pathological fracture
B. Visual disturbances
C. Peripheral neuropathy
D. All of the above (Correct Answer)

Explanation: Paraproteinemias (Monoclonal Gammopathies), such as Multiple Myeloma and Waldenström Macroglobulinemia, are characterized by the clonal proliferation of plasma cells or B-lymphocytes that produce an excess of monoclonal (M) protein [1]. The clinical manifestations are diverse and stem from direct organ infiltration or the systemic effects of the paraprotein. * **Pathological Fractures (Option A):** In Multiple Myeloma, plasma cells secrete osteoclast-activating factors (like RANKL and IL-6). This leads to extensive bone resorption and lytic lesions, making bones highly susceptible to fractures even with minimal trauma [1]. * **Visual Disturbances (Option B):** High levels of circulating M-protein (especially IgM in Waldenström’s) increase blood viscosity. This **Hyperviscosity Syndrome** causes sluggish blood flow, leading to retinal hemorrhages, "sausage-link" appearance of retinal veins, and blurred vision [1]. * **Peripheral Neuropathy (Option C):** Paraproteins can act as autoantibodies against myelin-associated glycoproteins (MAG) or deposit as amyloid fibrils (AL Amyloidosis) in the nerves, leading to sensory or motor deficits. Since all three manifestations are classic complications of paraproteinemias, **Option D** is the correct answer. **High-Yield Clinical Pearls for NEET-PG:** * **CRAB Criteria (Multiple Myeloma):** **C**alcium elevation, **R**enal insufficiency, **A**nemia, and **B**one lesions [1]. * **Bence-Jones Proteins:** These are free light chains found in urine; they do not show up on a standard dipstick (which detects albumin) but are detected by sulfosalicylic acid or urine electrophoresis [1]. * **Rouleaux Formation:** Seen on peripheral smear due to increased ESR caused by high protein levels [1]. * **Diagnosis:** Serum Protein Electrophoresis (SPEP) showing an **M-spike** is the initial screening test of choice [1].

Question 726: Paroxysmal nocturnal hemoglobinuria is due to what type of defect?

A. Acquired red cell defect (Correct Answer)
B. Congenital red cell defect
C. Autoimmune defect
D. Lead poisoning

Explanation: **Explanation:** **Paroxysmal Nocturnal Hemoglobinuria (PNH)** is a unique hematological disorder characterized by an **acquired intracorpuscular defect**. **1. Why "Acquired Red Cell Defect" is correct:** PNH is caused by a somatic mutation in the **PIGA gene** (Phosphatidylinositol Glycan class A) within a hematopoietic stem cell. This mutation is not inherited (congenital) but occurs during an individual's lifetime. The mutation leads to a deficiency of **GPI-anchored proteins** on the cell membrane, specifically **CD55 (DAF)** and **CD59 (MIRL)**. These proteins normally protect red cells from complement-mediated lysis. Their absence makes the RBCs abnormally sensitive to complement, leading to intravascular hemolysis. **2. Why other options are incorrect:** * **Congenital red cell defect:** Although PNH is a genetic mutation, it is **somatic**, not germline. It is not passed from parent to offspring, unlike Hereditary Spherocytosis or Thalassemia. * **Autoimmune defect:** Hemolysis in PNH is mediated by the **alternative complement pathway**, not by antibodies (immunoglobulins). Therefore, the Direct Coombs Test is characteristically **negative**. * **Lead poisoning:** This causes microcytic anemia by inhibiting enzymes in the heme synthesis pathway (ALAD and Ferrochelatase) and is associated with basophilic stippling, not complement-mediated lysis. **High-Yield Clinical Pearls for NEET-PG:** * **Triad of PNH:** Hemolytic anemia, Pancytopenia, and Venous thrombosis (often in unusual sites like the hepatic vein—Budd-Chiari syndrome). * **Gold Standard Diagnosis:** Flow cytometry showing absence of CD55 and CD59. * **Treatment:** **Eculizumab** (a monoclonal antibody against Complement C5) is the drug of choice. * **Association:** PNH is closely linked with **Aplastic Anemia** and may transform into Acute Myeloid Leukemia (AML).

Question 727: What concentration of methemoglobin appears as cyanosis?

A. 5 gm/dL
B. 2 gm/dL
C. 1.5 gm/dL (Correct Answer)
D. 12 gm/dL

Explanation: ### Explanation **1. Understanding the Correct Answer (1.5 gm/dL):** Cyanosis is a clinical sign characterized by the bluish discoloration of the skin and mucous membranes. It occurs when a specific absolute concentration of deoxygenated or abnormal hemoglobin is reached in the blood. * In the case of **Methemoglobinemia**, cyanosis becomes clinically apparent when the concentration of methemoglobin reaches **1.5 gm/dL** [1]. * Methemoglobin has a much higher "tinting" power than deoxyhemoglobin. Because it is dark/chocolate-colored, it produces visible cyanosis at a much lower absolute concentration than reduced hemoglobin. **2. Analysis of Incorrect Options:** * **5 gm/dL (Option A):** This is the threshold for **central cyanosis** caused by **reduced (deoxy) hemoglobin**. In patients with normal hemoglobin levels, cyanosis appears when at least 5 gm/dL of hemoglobin is in the deoxygenated state. * **2 gm/dL (Option B):** This is an incorrect threshold for both methemoglobin and deoxyhemoglobin. However, some texts note that sulfhemoglobinemia can cause cyanosis at levels as low as 0.5 gm/dL. * **12 gm/dL (Option D):** This level of methemoglobin (representing roughly 70-80% of total Hb in a normal adult) is typically **fatal** and far exceeds the threshold for initial clinical detection. **3. NEET-PG High-Yield Clinical Pearls:** * **The "Saturation Gap":** Suspect methemoglobinemia when there is a significant difference between the oxygen saturation measured by pulse oximetry ($SpO_2$ usually stays around 85%) and the calculated $SaO_2$ from an Arterial Blood Gas (ABG). * **Clinical Appearance:** Patients often present with "chocolate-colored blood" and cyanosis that does not improve with supplemental oxygen [1]. * **Drug Triggers:** Common culprits include Nitrites, Benzocaine, Dapsone, and Primaquine [2]. * **Antidote:** The treatment of choice is **Methylene Blue** (acts as an electron donor for NADPH-methemoglobin reductase). Note: Methylene blue is contraindicated in G6PD deficiency.

Question 728: What is the primary laboratory test used to screen for Beta-thalassemia trait?

A. Hemoglobin A2 (HbA2) (Correct Answer)
B. Hemoglobin F (HbF)
C. Osmotic fragility test
D. Coombs test

Explanation: The primary laboratory screening and diagnostic test for **Beta-thalassemia trait (minor)** is the measurement of **Hemoglobin A2 (HbA2)** levels, typically performed via High-Performance Liquid Chromatography (HPLC) or electrophoresis [1]. In Beta-thalassemia, there is a reduced synthesis of $\beta$-globin chains [2]. To compensate, the body increases the production of $\delta$-chains, which combine with $\alpha$-chains to form HbA2 ($\alpha_2\delta_2$) [3]. A **HbA2 level >3.5%** is the diagnostic hallmark of Beta-thalassemia trait. **Analysis of Incorrect Options:** * **B. Hemoglobin F (HbF):** While HbF may be slightly elevated in the trait (1–5%), it is significantly elevated in Beta-thalassemia *major*. It is not the primary screening marker for the trait. * **C. Osmotic Fragility Test:** This test is primarily used to diagnose **Hereditary Spherocytosis** (where fragility is increased). In thalassemia, cells are hypochromic and microcytic, actually showing *decreased* osmotic fragility. * **D. Coombs Test:** This is used to detect antibodies in **Autoimmune Hemolytic Anemia (AIHA)**. Thalassemia is a quantitative hemoglobinopathy, not an immune-mediated process. **High-Yield Clinical Pearls for NEET-PG:** * **Mentzer Index:** Used to differentiate Iron Deficiency Anemia (IDA) from Thalassemia trait. **MCV/RBC count <13** suggests Thalassemia; **>13** suggests IDA. * **Peripheral Smear:** Characterized by microcytic hypochromic anemia with **target cells** and basophilic stippling. * **NESTROFT:** (Naked Eye Single Tube Red Cell Osmotic Fragility Test) is often used as a cost-effective mass screening tool in field studies, but **HPLC (HbA2)** remains the gold standard for confirmation.

Question 729: Heterozygous sickle cell anemia provides protection against which of the following?

A. G6PD deficiency
B. Malaria (Correct Answer)
C. Thalassemia
D. Dengue fever

Explanation: The correct answer is **Malaria**. This phenomenon is a classic example of **heterozygote advantage** (balanced polymorphism). Individuals with sickle cell trait (HbAS) possess one normal beta-globin gene and one mutated gene ($Glu \to Val$ at position 6) [1]. This genotype provides a survival advantage against severe malaria, particularly ***Plasmodium falciparum*** [2]. **Mechanism of Protection:** 1. **Reduced Parasite Proliferation:** Sickle-prone RBCs have a shorter lifespan and tend to "sickle" when infected, leading to premature clearance by the splenic macrophages [2]. 2. **Impaired Cytoadherence:** Infected HbAS cells express fewer *P. falciparum* erythrocyte membrane protein 1 (PfEMP1) molecules, reducing the sequestration of cells in microvasculature (preventing cerebral malaria). 3. **Oxidative Stress:** The presence of HbS increases oxidative stress within the RBC, which inhibits optimal parasite growth [2]. **Analysis of Incorrect Options:** * **A & C (G6PD deficiency & Thalassemia):** These are distinct genetic hematological disorders. While they also offer some protection against malaria, they are not "protected against" by the sickle cell trait. In fact, these conditions can co-exist with HbS (e.g., Sickle-Thalassemia syndrome) [1]. * **D (Dengue fever):** Dengue is a viral hemorrhagic fever transmitted by the *Aedes* mosquito. There is no established genetic protection offered by hemoglobinopathies against viral replication or the clinical course of Dengue. **High-Yield Clinical Pearls for NEET-PG:** * **Sickle Cell Trait (HbAS):** Usually asymptomatic; patients have normal life expectancy and normal hemoglobin levels. * **The "Sickle" Trigger:** In HbAS, sickling only occurs under extreme conditions like severe hypoxia (e.g., unpressurized aircraft) or extreme dehydration. * **Screening:** Solubility test is used for screening; **Hemoglobin Electrophoresis** is the gold standard for diagnosis (HbA: 50-60%, HbS: 35-45%, HbF: <2%) [1]. * **Renal Complication:** The most common clinical manifestation of sickle cell trait is **painless hematuria** due to papillary necrosis.

Question 730: In which of the following conditions that cause polycythemia is the serum erythropoietin extremely low?

A. Dehydration
B. Renal cell carcinoma
C. Congenital heart disease
D. Polycythemia vera (Correct Answer)

Explanation: The key to answering this question lies in distinguishing between **Primary** and **Secondary Polycythemia**. **1. Why Polycythemia Vera (PV) is correct:** Polycythemia Vera is a **Primary Polycythemia**, a myeloproliferative neoplasm characterized by an autonomous overproduction of red blood cells by the bone marrow, independent of Erythropoietin (EPO) stimulation. In >95% of cases, this is due to a **JAK2 V617F mutation** [1]. Because the red cell mass is high, the body’s normal physiological feedback loop suppresses the production of EPO in the kidneys [2]. Therefore, an **extremely low or subnormal serum EPO level** is a major diagnostic criterion for PV. **2. Why the other options are incorrect:** * **Dehydration (Option A):** This causes **Relative Polycythemia**. The red cell mass is normal, but the plasma volume is decreased. EPO levels remain within the normal range. * **Renal Cell Carcinoma (Option B):** This is a cause of **Secondary Polycythemia**. Certain tumors (RCC, Hepatoma, Cerebellar Hemangioblastoma) can ectopically produce EPO, leading to **elevated** EPO levels. * **Congenital Heart Disease (Option C):** Cyanotic heart diseases cause chronic tissue hypoxia. This triggers the kidneys to increase EPO production physiologically to improve oxygen-carrying capacity [2]. Thus, EPO levels are **elevated**. **High-Yield Clinical Pearls for NEET-PG:** * **Diagnostic Triad for PV:** Increased hemoglobin/hematocrit, JAK2 mutation, and low serum EPO [1]. * **Clinical Sign:** **Aquagenic pruritus** (itching after a warm bath) is highly specific for PV [1]. * **Complication:** Patients are at high risk for both arterial and venous thrombosis (e.g., Budd-Chiari Syndrome) [1]. * **Treatment of choice:** Therapeutic phlebotomy (target Hct <45%) and low-dose aspirin.

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Anemia Evaluation and Management

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Hemoglobinopathies

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Thalassemias

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Platelet Disorders

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Coagulation Disorders

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Thrombotic Disorders

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Leukemias

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Lymphomas

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Multiple Myeloma and Plasma Cell Disorders

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Myeloproliferative Neoplasms

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Transfusion Medicine

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Hematopoietic Stem Cell Transplantation

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Hematology — MCQs

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