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?
TRUS in carcinoma prostate is most useful for?
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 -
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: TRUS in carcinoma prostate is most useful for?
- A. Evaluating nearby structures for involvement
- B. Identifying suspicious areas in the prostate
- C. Estimating the size of the prostate
- D. Assisting in targeted prostate biopsies (Correct Answer)
Explanation: ***Assisting in targeted prostate biopsies*** - **TRUS** (Transrectal Ultrasound) provides real-time imaging, which is crucial for **guiding biopsy needles** accurately to suspicious areas within the prostate that may not be palpable. - This guidance increases the diagnostic yield of biopsies, ensuring samples are taken from potentially cancerous regions. *Evaluating nearby structures for involvement* - While TRUS can visualize the immediate surrounding structures like the **seminal vesicles**, its primary role is not for comprehensive staging of tumor extension outside the prostate, which is better achieved with MRI. - It helps in assessing direct invasion into seminal vesicles but has limitations for wider regional lymph node or distant metastasis evaluation. *Identifying suspicious areas in the prostate* - TRUS can identify **hypoechoic lesions** within the prostate, which are often associated with cancer, but these findings are not specific, and many benign conditions can mimic cancer. - The main utility is not solely in identifying these areas, but in using this identification to guide subsequent biopsies for definitive diagnosis. *Estimating the size of the prostate* - TRUS is highly effective for accurately measuring prostate volume, which is important for estimating PSA density and for surgical planning in benign prostatic hyperplasia (BPH). - However, while it can measure size, this is not its most diagnostically critical role in the context of carcinoma prostate when considering its unique capabilities.
Question 8: 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 9: 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 10: 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.
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