Biomarkers in Disease Management — MCQs
Techniques used for protein expression proteomics study include:
Preferred biochemical marker(s) in patients presenting with myocardial infarction:
Most sensitive method of monitoring cardiovascular ischemia in the perioperative period is -
AFP is a tumour marker for which of the following?
If a biochemical test gives the same reading for a sample on repeated testing, it is inferred that the measurement is -
What is the technique for accurate quantification of gene expression?
Procalcitonin is considered a marker for:
A patient with gastric cancer shows positive CEA. What is its significance?
A young lady complains of sore throat for 3 days along with fever and headache. On examination, she was severely dehydrated, her BP was found to be 90/ 50 mm Hg and on the distal aspect of the cuff, small red spots were noted. What could be the most probable etiological agent responsible for causing these symptoms -
Plasma cholinesterase levels are affected by various conditions. Which of the following conditions does not typically reduce plasma cholinesterase levels?
Biomarkers in Disease Management Indian Medical PG Practice Questions and MCQs
Question 1: Techniques used for protein expression proteomics study include:
- A. PolyAcrylamide Gel Electrophoresis (PAGE)
- B. Gene Expression Analysis (indirectly related to proteomics)
- C. Mass Spectrometry
- D. All of the options (Correct Answer)
Explanation: ***All of the options*** - All listed techniques—**Polyacrylamide Gel Electrophoresis (PAGE)**, **Gene Expression Analysis**, and **Mass Spectrometry**—are used in protein expression proteomics studies, either directly or indirectly, to analyze and quantify proteins. - The integration of these various techniques provides a comprehensive approach to understanding protein expression profiles. *PolyAcrylamide Gel Electrophoresis (PAGE)* - **PAGE** (including 1D and 2D-PAGE) is a fundamental technique for separating proteins based on their **molecular weight** and **isoelectric point**, which is crucial for visualizing and quantifying expressed proteins. - It often serves as an initial separation step before more detailed analysis, such as **mass spectrometry**. *Gene Expression Analysis (indirectly related to proteomics)* - Although **gene expression analysis** (e.g., using **RT-PCR** or **microarrays**) measures mRNA levels, it is indirectly related to proteomics because mRNA levels often **correlate with protein levels**. - It provides insights into the **transcriptional regulation** that influences protein expression, complementing direct protein analysis. *Mass Spectrometry* - **Mass spectrometry** is a powerful and widely used technique in proteomics for **identifying, quantifying, and characterizing proteins** and peptides by measuring their **mass-to-charge ratio**. - It can be used for both **discovery proteomics** (identifying novel proteins) and **targeted proteomics** (quantifying specific proteins).
Question 2: Preferred biochemical marker(s) in patients presenting with myocardial infarction:
- A. Cardiac specific Troponins (Correct Answer)
- B. All of the options
- C. Myoglobin
- D. CK-MB
Explanation: ***Cardiac specific Troponins*** - **Cardiac troponins** (cTnI and cTnT) are the preferred and most sensitive and specific biomarkers for diagnosing **myocardial infarction (MI)**. - They are proteins released into the bloodstream when myocardial cells are damaged, and their levels rise within hours of MI onset and remain elevated for several days. *All of the options* - While other markers like **CK-MB** and **Myoglobin** were historically used, **cardiac troponins** have superior specificity and sensitivity for MI. - The latest guidelines from major cardiology societies recommend troponins as the primary diagnostic markers. *Myoglobin* - **Myoglobin** is an early marker, but it is not specific to cardiac muscle and can be elevated in various conditions involving skeletal muscle damage. - Its short half-life means it can return to normal quickly, making it less reliable for diagnosing MI, especially if there's a delay in presentation. *CK-MB* - **Creatine Kinase-MB (CK-MB)** is a more specific marker than total CK for cardiac muscle damage but is still less specific than cardiac troponins. - It can be elevated in conditions like **myocarditis** or **pericarditis**, and its levels typically peak and decline earlier than troponins, limiting its diagnostic window.
Question 3: Most sensitive method of monitoring cardiovascular ischemia in the perioperative period is -
- A. NIBP
- B. ECG
- C. Pulse oximeter
- D. TEE (Correct Answer)
Explanation: ***TEE*** - **Transesophageal echocardiography (TEE)** is the most sensitive method for detecting perioperative myocardial ischemia because it can visualize **regional wall motion abnormalities** and changes in **ventricular function** much earlier than ECG. - **Ischemia** directly impairs the contractility of the affected myocardium, leading to subtle changes in wall motion that TEE can identify. *NIBP* - **Non-invasive blood pressure (NIBP)** monitoring can detect **hemodynamic changes** (like hypotension or hypertension) that may precede or accompany ischemia. - However, these changes are **non-specific** and occur relatively late, making NIBP a less sensitive indicator of early ischemia. *ECG* - **Electrocardiography (ECG)** monitors the electrical activity of the heart and can detect **ST-segment changes** indicative of ischemia. - While useful, ECG changes may appear later than wall motion abnormalities, and **silent ischemia** can be missed if the leads are not optimally placed or if the ischemia does not produce significant electrical changes. *Pulse oximeter* - A **pulse oximeter** measures **oxygen saturation** in the peripheral blood. - It is primarily used to assess **respiratory function** and tissue oxygenation, and it does not directly monitor myocardial ischemia or cardiac function.
Question 4: AFP is a tumour marker for which of the following?
- A. Chordoma
- B. RCC
- C. HCC (Correct Answer)
- D. Oncocytoma
Explanation: ***Correct Option: HCC*** - **Alpha-fetoprotein (AFP)** is the most widely recognized tumor marker for **Hepatocellular Carcinoma (HCC)**, the most common primary liver cancer [1] - Elevated AFP levels (>400 ng/mL) are highly suggestive of HCC and are used for **diagnosis, monitoring treatment response, and surveillance for recurrence** [1] - AFP is also elevated in **yolk sac tumors** and some **non-seminomatous germ cell tumors**, but HCC remains the primary clinical association [1] *Incorrect: Chordoma* - **Chordomas** are rare malignant bone tumors arising from notochord remnants, typically in the skull base or sacrum - **No specific tumor marker** is routinely used; brachyury (transcription factor) may be used as an immunohistochemical marker for diagnosis - AFP is not associated with chordomas *Incorrect: RCC* - **Renal Cell Carcinoma (RCC)** is the most common kidney malignancy - No highly specific tumor markers exist for RCC; occasionally **elevated LDH, alkaline phosphatase, or calcium** may be seen - AFP is not a marker for RCC *Incorrect: Oncocytoma* - **Renal oncocytoma** is a **benign** renal tumor composed of oncocytes (cells with abundant mitochondria) - Diagnosed primarily by **imaging and histology**, not serum markers - AFP has no role in oncocytoma diagnosis or monitoring **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 399-400.
Question 5: If a biochemical test gives the same reading for a sample on repeated testing, it is inferred that the measurement is -
- A. Specific
- B. Accurate
- C. Sensitive
- D. Precise (Correct Answer)
Explanation: ***Precise*** - **Precision** refers to the consistency or **reproducibility** of measurements. If repeated tests yield similar results, the measurement is considered precise. - A precise test may not necessarily be accurate, but it consistently gives the same value, highlighting its **reliability** in producing repeatable results. *Specific* - **Specificity** refers to a test's ability to correctly identify individuals who do **not** have a particular condition (i.e., true negatives). - It measures how well a test avoids **false positives**, indicating that a positive result is truly associated with the target analyte. *Accurate* - **Accuracy** refers to how close a measured value is to the true or **actual value**. - A test is accurate if it provides results that are close to the correct value, not simply if they are consistently the same. *Sensitive* - **Sensitivity** refers to a test's ability to correctly identify individuals who **do** have a particular condition (i.e., true positives). - It measures how well a test avoids **false negatives**, indicating that a negative result truly means the condition is absent.
Question 6: What is the technique for accurate quantification of gene expression?
- A. PCR
- B. Real-Time Reverse Transcriptase PCR (Correct Answer)
- C. Reverse Transcriptase PCR
- D. Northern blot
Explanation: ***Real-Time Reverse Transcriptase PCR*** - This technique allows for the **quantification of gene expression** by concurrently reverse-transcribing RNA to cDNA and amplifying it while monitoring the accumulation of DNA in real-time using fluorescent reporters. - The ** threshold cycle (Ct) value** is inversely proportional to the initial amount of target mRNA, enabling precise quantification. *Northern blot* - This method is used to detect **RNA sequences** and can provide semi-quantitative data about gene expression levels based on band intensity. - However, it is generally **less sensitive** and provides less precise quantification compared to real-time PCR. *PCR* - **Standard PCR** amplifies DNA, but it is not directly used for gene expression quantification as it starts with DNA templates. - While it can be used to detect the presence of a gene, it does not quantify its expression without further modifications or additional steps like reverse transcription and real-time monitoring. *Reverse Transcriptase PCR* - This technique involves **reverse transcribing RNA into cDNA** and then performing standard PCR to amplify the cDNA. - While it confirms the presence of mRNA and allows for cDNA amplification, it is a **qualitative or semi-quantitative** method for expression, as the endpoint detection does not accurately reflect initial mRNA concentration due to plateau effects.
Question 7: Procalcitonin is considered a marker for:
- A. Sepsis (Correct Answer)
- B. Medullary thyroid carcinoma
- C. Parathyroid adenoma
- D. Vitamin D resistant rickets
Explanation: **Sepsis** - **Procalcitonin** (PCT) levels significantly rise in response to bacterial infections and **sepsis**, making it a useful diagnostic and prognostic marker. - Its levels correlate with the severity of bacterial infection and can help differentiate bacterial from viral etiologies. *Medullary thyroid carcinoma* - **Medullary thyroid carcinoma** (MTC) is characterized by the production of **calcitonin**, a different hormone from procalcitonin, by the parafollicular C cells of the thyroid. - While calcitonin is a tumor marker for MTC, **procalcitonin** is not. *Vitamin D resistant rickets* - **Vitamin D resistant rickets** (also known as X-linked hypophosphatemia) is a genetic disorder characterized by impaired phosphate reabsorption in the kidneys [1]. - It is associated with low phosphate levels and bone deformities, but not with elevated procalcitonin [1]. *Parathyroid adenoma* - A **parathyroid adenoma** leads to primary hyperparathyroidism, characterized by excessive production of **parathyroid hormone (PTH)** [1]. - This results in hypercalcemia and hypophosphatemia, with no direct link to procalcitonin levels [1].
Question 8: A patient with gastric cancer shows positive CEA. What is its significance?
- A. Prognostic (Correct Answer)
- B. Diagnostic
- C. Therapeutic
- D. Screening
Explanation: ***Prognostic*** - A positive **carcinoembryonic antigen (CEA)** in gastric cancer indicates **larger tumor burden** and more advanced disease [1] - Elevated preoperative CEA levels are associated with **poorer prognosis**, higher risk of recurrence, and decreased survival [1] - CEA levels can be used to **monitor treatment response** and detect early recurrence after curative resection [1] - Higher CEA values correlate with advanced stage, lymph node involvement, and distant metastases *Diagnostic* - CEA is **not specific enough** for diagnosing gastric cancer as it can be elevated in other malignancies (colorectal, pancreatic, lung) and benign conditions (smoking, cirrhosis, inflammatory bowel disease) [2] - Diagnosis of gastric cancer requires **endoscopic biopsy** with histopathological examination - CEA may be normal even in confirmed gastric cancer cases (limited sensitivity) [2] *Therapeutic* - CEA is a **tumor marker**, not a therapeutic agent or treatment modality - While CEA levels help guide treatment decisions and monitor response, the marker itself has no therapeutic role - Treatment decisions are based on staging, histology, and patient factors, not solely on CEA values *Screening* - CEA lacks sufficient **sensitivity and specificity** for population-based screening of gastric cancer [2] - Screening for gastric cancer uses **endoscopy** in high-risk populations, not serum tumor markers - CEA is primarily used for post-treatment surveillance in patients with known cancer, not for detecting occult disease in asymptomatic individuals **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 254-255. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, p. 346.
Question 9: A young lady complains of sore throat for 3 days along with fever and headache. On examination, she was severely dehydrated, her BP was found to be 90/ 50 mm Hg and on the distal aspect of the cuff, small red spots were noted. What could be the most probable etiological agent responsible for causing these symptoms -
- A. Brucella suis
- B. Neisseria meningitidis (Correct Answer)
- C. Brucella abortus
- D. Staphylococcus aureus
Explanation: Neisseria meningitidis - The combination of sore throat, fever, headache, severe dehydration, hypotension, and petechiae (small red spots from broken capillaries, often seen with bleeding diathesis) is highly suggestive of meningococcemia [1]. - Neisseria meningitidis can cause fulminant sepsis and meningitis, leading to rapid progression of symptoms including DIC and widespread petechial rashes due to vasculitis [2]. Brucella suis - Brucellosis typically presents as an insidious illness with undulating fever, arthralgia, and organomegaly, not sudden onset severe symptoms with dehydration and petechiae. - While it can be severe, it does not commonly manifest with the acute, dramatic hemorrhagic signs seen in this patient. Brucella abortus - Similar to Brucella suis, Brucella abortus causes brucellosis, which is a chronic or subacute infection. - The clinical picture of acute onset, severe dehydration, hypotension, and petechiae points away from brucellosis. Staphylococcus aureus - Staphylococcus aureus can cause various infections, including sepsis, but a sore throat and the specific presentation of petechiae with hypotension following an apparent upper respiratory tract infection are less characteristic [3]. - While S. aureus can produce toxins leading to toxic shock syndrome, meningococcal sepsis is a more direct fit for the rapid onset and hemorrhagic signs.
Question 10: Plasma cholinesterase levels are affected by various conditions. Which of the following conditions does not typically reduce plasma cholinesterase levels?
- A. Pregnancy
- B. Liver disease
- C. Malnutrition
- D. Chronic renal failure (Correct Answer)
Explanation: ***Chronic renal failure*** - While chronic renal failure can cause various metabolic derangements, it does not typically lead to a significant **reduction in plasma cholinesterase levels**. - Plasma cholinesterase is primarily synthesized in the liver, and its levels are more directly impacted by conditions affecting **liver function** or **protein synthesis** [1]. *Pregnancy* - **Plasma cholinesterase levels** are known to decrease during normal pregnancy, particularly in the third trimester. - This reduction is thought to be due to **hormonal changes** and possibly increased plasma volume. *Liver disease* - Since plasma cholinesterase is synthesized in the **liver**, severe **liver disease** (e.g., cirrhosis, acute hepatitis) significantly impairs its production [1]. - This leads to a marked **reduction in circulating enzyme levels**, which can affect drug metabolism [1]. *Malnutrition* - **Severe malnutrition**, especially protein-calorie malnutrition, can lead to decreased synthesis of many proteins, including plasma cholinesterase. - This is because the body lacks the necessary **amino acids** for enzyme production.
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