Drug-Induced Blood Dyscrasias Indian Medical PG Practice Questions and MCQs
Practice Indian Medical PG questions for Drug-Induced Blood Dyscrasias. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Drug-Induced Blood Dyscrasias Indian Medical PG Question 1: Which of the following statements best describes the underlying mechanism of heparin-induced thrombocytopenia?
- A. Low molecular weight heparin can also cause heparin-induced thrombocytopenia.
- B. Vitamin K is not an antidote for heparin-induced thrombocytopenia.
- C. Heparin-induced thrombocytopenia can occur after several days of heparin therapy.
- D. Antibodies are formed against heparin-platelet factor 4 complexes. (Correct Answer)
Drug-Induced Blood Dyscrasias Explanation: **_Antibodies are formed against platelet factor 4._**
- The underlying mechanism of **heparin-induced thrombocytopenia (HIT)** involves the formation of antibodies against complexes of **heparin and platelet factor 4 (PF4)** [2].
- These antibodies bind to the **heparin-PF4 complexes** on the surface of platelets, leading to platelet activation, aggregation, and consumption, which results in thrombocytopenia and a prothrombotic state [2].
*Low molecular weight heparin can also cause heparin-induced thrombocytopenia.*
- While **low molecular weight heparin (LMWH)** has a lower incidence of causing HIT compared to unfractionated heparin, it can still trigger the condition [1], [2].
- This is because LMWH, like unfractionated heparin, can form complexes with PF4, leading to the same immune response in susceptible individuals [2].
*Vitamin K is not an antidote for heparin-induced thrombocytopenia.*
- **Vitamin K** is the antidote for warfarin overdose, which works by reversing its anticoagulant effects [3].
- It has no role as an antidote for HIT because HIT is an **immune-mediated reaction** involving platelet activation, not a direct anticoagulant effect that can be reversed by Vitamin K [2].
*Heparin-induced thrombocytopenia can occur after several days of heparin therapy.*
- HIT typically manifests after **5 to 10 days of heparin exposure**, as it takes time for the immune system to produce antibodies against the heparin-PF4 complexes [2].
- However, in patients with prior exposure to heparin, HIT can occur much sooner, even within **24 hours**, due to pre-existing antibodies.
Drug-Induced Blood Dyscrasias Indian Medical PG Question 2: A patient of schizophrenia is being treated with clozapine. For which rare but serious side effects should he be monitored?
- A. Seizures
- B. Agranulocytosis (Correct Answer)
- C. Hepatomegaly
- D. Renal bleed
Drug-Induced Blood Dyscrasias Explanation: ***Agranulocytosis*** - **Agranulocytosis** is a severe and potentially fatal reduction in white blood cells (specifically neutrophils) that can occur with clozapine use [2, 3]. - This is the **rare but serious side effect** that requires mandatory monitoring, occurring in **0.8-2%** of patients. - Patients on clozapine require routine **complete blood count (CBC)** monitoring: **weekly for the first 6 months**, then biweekly for months 6-12, then monthly thereafter . - This is the primary reason clozapine has restricted use despite being the most effective antipsychotic for treatment-resistant schizophrenia. *Seizures* - While clozapine can lower the **seizure threshold** (especially at higher doses), seizures occur in **1-2%** of patients and are **dose-dependent** . - Seizures are a known side effect that warrants dosage adjustment, but they are **not as rare** as agranulocytosis and do not require the same intensive blood monitoring protocol. - Management involves dose reduction or adding anticonvulsants. *Hepatomegaly* - **Hepatic dysfunction** can occur with clozapine, but **hepatomegaly** (enlarged liver) itself is not one of its rare, life-threatening side effects requiring specific monitoring above other, more severe issues. - Liver enzyme elevation may be monitored, but this is not the primary "rare but serious" concern. *Renal bleed* - **Renal complications** or **renal bleeding** are not recognized as significant or specifically monitored rare side effects of clozapine. - Clozapine's major concerns primarily involve hematologic (agranulocytosis), cardiovascular (myocarditis), and metabolic systems.
Drug-Induced Blood Dyscrasias Indian Medical PG Question 3: Which of the following types of leukemia is administered prophylactic methotrexate for CNS prophylaxis –
- A. AML
- B. CLL
- C. CML
- D. ALL (Correct Answer)
Drug-Induced Blood Dyscrasias Explanation: ***ALL***
- **Acute Lymphoblastic Leukemia (ALL)** has a high propensity for **central nervous system (CNS) involvement**, necessitating prophylactic intrathecal methotrexate to prevent CNS relapse [1].
- Prophylactic treatment of the CNS is a standard component of ALL treatment protocols due to the risk of leukemic cell infiltration into the brain and spinal cord [1].
*AML*
- **Acute Myeloid Leukemia (AML)** has a lower incidence of CNS involvement compared to ALL, so prophylactic CNS treatment is generally not routine unless specific risk factors are present.
- While CNS involvement can occur in AML, it is more commonly treated with systemic chemotherapy that has CNS penetration or intrathecal treatment only when CNS disease is confirmed.
*CLL*
- **Chronic Lymphocytic Leukemia (CLL)** rarely involves the CNS, and prophylactic CNS treatment is not part of standard management.
- When CNS involvement does occur in CLL, it is an aggressive, late-stage complication and typically requires specific, targeted therapy rather than prophylaxis.
*CML*
- **Chronic Myeloid Leukemia (CML)** has an extremely low risk of CNS involvement, especially in the chronic phase, and therefore, prophylactic CNS treatment is not administered.
- CNS involvement in CML is usually seen during a blast crisis and is rare, making prophylaxis unnecessary.
Drug-Induced Blood Dyscrasias Indian Medical PG Question 4: Which of the following statements is true regarding drug-induced lupus erythematosus (DILE)?
- A. CNS manifestations are common in DILE.
- B. Renal involvement is common in DILE.
- C. Antihistone antibodies are commonly found in DILE. (Correct Answer)
- D. All patients with antibodies progress to systemic lupus erythematosus.
Drug-Induced Blood Dyscrasias Explanation: ***Antihistone antibodies are commonly found in DILE.***
- The presence of **antihistone antibodies** is a hallmark of drug-induced lupus erythematosus, detected in a majority of cases.
- This antibody profile helps differentiate DILE from idiopathic systemic lupus erythematosus (SLE), where other autoantibodies like anti-dsDNA are more prominent.
*CNS manifestations are common in DILE.*
- **Central nervous system (CNS) involvement** is rare in DILE, distinguishing it from idiopathic SLE where neuropsychiatric symptoms are more prevalent.
- While headaches and mild cognitive changes can occur, severe manifestations like seizures or psychosis are not typical of DILE.
*Renal involvement is common in DILE.*
- **Renal involvement**, such as glomerulonephritis, is highly uncommon in DILE, unlike idiopathic SLE where it is a significant cause of morbidity.
- If significant renal disease is present in a patient suspected of DILE, it warrants a re-evaluation for idiopathic SLE or another diagnosis.
*All patients with antibodies progress to systemic lupus erythematosus.*
- Not all patients who develop antibodies, such as **antihistone antibodies**, will progress to full-blown DILE or systemic lupus erythematosus.
- The condition typically resolves upon discontinuation of the offending drug, and the presence of antibodies alone is not sufficient for diagnosis, requiring clinical symptoms.
Drug-Induced Blood Dyscrasias Indian Medical PG Question 5: Which of the following hematological problems may be precipitated by parvovirus?
- A. Aplastic crisis (Correct Answer)
- B. Hemolytic crisis
- C. Thrombocytopenia
- D. Pancytopenia
Drug-Induced Blood Dyscrasias Explanation: ***Aplastic crisis***
- Parvovirus B19 preferentially infects and destroys **erythroid progenitor cells** in the bone marrow, leading to a temporary halt in red blood cell production [1].
- This can precipitate an **aplastic crisis**, especially in individuals with underlying chronic hemolytic anemias (e.g., **sickle cell disease** or **hereditary spherocytosis**), where red blood cell lifespan is already shortened [2].
*Hemolytic crisis*
- A hemolytic crisis involves an **accelerated destruction of red blood cells**, leading to a sudden drop in hemoglobin.
- While parvovirus can indirectly worsen anemia, it primarily affects red cell production rather than directly increasing their destruction, acting more as a trigger for a production problem than a hemolytic one [1].
*Thrombocytopenia*
- **Thrombocytopenia** is characterized by a low platelet count, which can lead to bleeding disorders.
- While viral infections can sometimes cause mild myelosuppression affecting platelets, parvovirus B19 is not typically associated with severe or primary thrombocytopenia.
*Pancytopenia*
- **Pancytopenia** is a reduction in all three blood cell lines (red blood cells, white blood cells, and platelets).
- While parvovirus can cause a transient aplastic crisis (affecting red cells), it rarely causes a severe, sustained suppression of all cell lines to be classified as true pancytopenia, though some transient leukopenia may occur [1].
Drug-Induced Blood Dyscrasias Indian Medical PG Question 6: A patient with a history of penicillin allergy is admitted with bacterial meningitis. After receiving intravenous antibiotics, she develops a severe reaction. Which of the following drugs is most likely responsible for her condition?
- A. Chloramphenicol
- B. Gentamicin
- C. Doxycycline
- D. Vancomycin (Correct Answer)
Drug-Induced Blood Dyscrasias Explanation: ***Vancomycin***
- **Vancomycin infusion reaction** (formerly "red man syndrome") is a common adverse effect, especially with rapid intravenous administration, characterized by **flushing, rash, pruritus**, and sometimes **hypotension** or **angioedema**.
- This reaction results from **non-IgE-mediated mast cell degranulation**, leading to histamine release, and is not directly related to penicillin allergy but can be mistaken for an allergic reaction.
*Gentamicin*
- Gentamicin is an **aminoglycoside** and is not typically associated with severe immediate hypersensitivity reactions like the one described.
- Its main toxicities include **nephrotoxicity** and **ototoxicity**, often occurring with prolonged use or high concentrations.
*Chloramphenicol*
- Chloramphenicol is associated with serious but less common adverse effects such as **bone marrow suppression** (aplastic anemia) or **grey baby syndrome** in neonates.
- It does not commonly cause acute, severe hypersensitivity reactions presenting as a rash and flushing.
*Doxycycline*
- Doxycycline is a **tetracycline antibiotic** and is generally well-tolerated, though it can cause photosensitivity, gastrointestinal upset, and esophageal irritation.
- Like the other incorrect options, it does not typically induce acute, severe infusion reactions mimicking an allergic response in the way vancomycin does, especially in a penicillin-allergic patient.
Drug-Induced Blood Dyscrasias Indian Medical PG Question 7: The most classic dietary trigger for acute hemolytic anemia in G6PD deficiency is which of the following?
- A. Viral upper respiratory infections only
- B. Vitamin C supplements
- C. Fava beans (Correct Answer)
- D. Folic acid deficiency
Drug-Induced Blood Dyscrasias Explanation: **Fava beans**
- **Fava beans** contain high concentrations of **vicine and convicine**, which are converted into **divicine and isouramil**. These compounds produce **reactive oxygen species** that overwhelm the erythrocyte's antioxidant defense mechanisms, especially in individuals with **G6PD deficiency** [2].
- In individuals with **G6PD deficiency**, the inability to produce sufficient **NADPH** results in inadequate levels of **reduced glutathione**, making red blood cells vulnerable to **oxidative stress** induced by these fava bean metabolites, leading to **hemolysis** [1, 3].
*Viral upper respiratory infections only*
- While **infections (bacterial or viral)** can trigger **hemolytic crises** in G6PD deficient individuals by causing **oxidative stress** and inflammation, they are not a dietary trigger [3, 4].
- The question specifically asks for a **dietary trigger**, which excludes infections as the primary cause.
*Vitamin C supplements*
- While **large doses of vitamin C (ascorbic acid)** can act as a **pro-oxidant** and potentially induce some oxidative stress, it is generally not considered a classic or strong trigger for acute hemolytic anemia in G6PD deficiency at typical supplement doses.
- **Fava beans** are far more potent and well-documented as a dietary trigger for this condition [2].
*Folic acid deficiency*
- **Folic acid deficiency** does not directly cause acute hemolytic anemia in G6PD deficiency; it typically leads to **megaloblastic anemia** due to impaired DNA synthesis [4].
- While folic acid supplementation is often given to G6PD deficient patients with chronic hemolysis to support increased red blood cell production, its deficiency does not induce oxidative hemolysis.
Drug-Induced Blood Dyscrasias Indian Medical PG Question 8: Drug Induced Lupus is caused by all except
- A. Hydralazine
- B. Sulphonamides
- C. Isoniazid
- D. Procaine (Correct Answer)
Drug-Induced Blood Dyscrasias Explanation: ***Procaine***
- While **procainamide**, a derivative of procaine, is a known cause of **drug-induced lupus (DIL)**, **procaine** itself is not typically implicated.
- Procaine is a **local anesthetic** and its mechanism of action does not commonly lead to the immunological reactions seen in DIL.
*Hydralazine*
- **Hydralazine** is a well-established cause of **drug-induced lupus (DIL)**, particularly with higher doses and prolonged use.
- It frequently results in the development of **anti-histone antibodies**, a hallmark of DIL.
*Sulphonamides*
- Various **sulphonamide antibiotics** (e.g., sulfasalazine, sulfamethoxazole) are known to induce **lupus-like syndromes**.
- These drugs can trigger immune responses leading to symptoms characteristic of **systemic lupus erythematosus (SLE)**.
*Isoniazid*
- **Isoniazid**, an anti-tuberculosis medication, is a recognized cause of **drug-induced lupus (DIL)**.
- It often leads to the formation of **anti-histone antibodies** and clinical manifestations resembling spontaneous lupus.
Drug-Induced Blood Dyscrasias Indian Medical PG Question 9: Ulipristal acetate (progesterone receptor modulator) should not be prescribed as emergency contraceptive in women with
- A. liver dysfunction (Correct Answer)
- B. glaucoma
- C. coagulopathy
- D. kidney failure
Drug-Induced Blood Dyscrasias Explanation: ***Correct: liver dysfunction***
- **Ulipristal acetate** is extensively metabolized in the **liver** by the CYP450 enzyme system, predominantly CYP3A4.
- In individuals with **severe hepatic impairment**, the metabolism of ulipristal acetate can be impaired, leading to increased plasma concentrations and potential adverse effects.
- **Severe liver dysfunction** is a documented contraindication in product labeling.
*Incorrect: glaucoma*
- There is **no known contraindication** for ulipristal acetate use in individuals with **glaucoma**.
- Its mechanism of action primarily involves progesterone receptors and does not directly impact intraocular pressure.
*Incorrect: coagulopathy*
- Ulipristal acetate does **not significantly affect blood coagulation** parameters or platelet function.
- It is not contraindicated in individuals with **coagulopathy**, unlike some estrogen-containing contraceptives.
*Incorrect: kidney failure*
- While urinary excretion of ulipristal acetate metabolites occurs, the **primary elimination pathway is fecal** (approximately 90%).
- **Kidney failure** is not considered a contraindication, and dose adjustments are generally not required.
Drug-Induced Blood Dyscrasias Indian Medical PG Question 10: Which of the following drugs can lead to pemphigus?
- A. Carbamazepine
- B. Penicillamine (Correct Answer)
- C. Isoniazid
- D. Furosemide
Drug-Induced Blood Dyscrasias Explanation: ***Penicillamine***
- **Penicillamine** is a well-known drug that can induce **pemphigus**, often through mechanisms involving alterations in **desmosome structure** or function.
- The drug's sulfhydryl groups are thought to interfere with the integrity of **desmoglein proteins**, leading to blister formation.
*Isoniazid*
- **Isoniazid** is a first-line antituberculosis drug primarily associated with **hepatotoxicity** and **peripheral neuropathy**.
- It is not typically implicated in the development of **pemphigus**.
*Carbamazepine*
- **Carbamazepine** is an anticonvulsant that can cause various cutaneous reactions, most notably **Stevens-Johnson syndrome (SJS)** and **toxic epidermal necrolysis (TEN)**.
- While it can cause severe skin reactions, **pemphigus** is not a common side effect of carbamazepine.
*Furosemide*
- **Furosemide** is a loop diuretic that can cause **photosensitivity**, rashes, and rarely, severe skin reactions like **erythema multiforme**.
- It is not recognized as a drug that induces **pemphigus**.
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