Nephrogenic Systemic Fibrosis — MCQs
Gadolinium is a contrast agent used for:
What is the diagnosis for this patient with end-stage renal disease who developed skin changes after an imaging procedure?
Most specific test for diagnosing Fabry disease on kidney biopsy?
A renal biopsy shows 'bamboo spine' pattern in arterioles. Which immunofluorescence finding would best support thrombotic microangiopathy?
Which of the following indicates radiograph contrast induced nephropathy?
GFR for assessment of impaired renal function is best measured by
At what glomerular filtration rate (GFR) is the term "end-stage renal disease (ESRD)" typically classified?
All of the following are used in a patient with decreased renal function (reduced GFR) to avoid contrast nephropathy except?
Which of the following conditions is associated with contrast nephropathy?
Which of the following investigations must be performed before administering contrast to a patient?
Nephrogenic Systemic Fibrosis Indian Medical PG Practice Questions and MCQs
Question 1: Gadolinium is a contrast agent used for:
- A. CT - angiography
- B. Bronchography
- C. MRI - Imaging (Correct Answer)
- D. Contrast Sonography
Explanation: ***MRI - Imaging*** - **Gadolinium** is a paramagnetic substance commonly used as a contrast agent in **Magnetic Resonance Imaging (MRI)**. - It works by altering the **T1 relaxation times** of protons in tissues, enhancing the signal and improving the visibility of certain structures or pathologies like **tumors** or **inflammation**. *CT - angiography* - **CT angiography** typically uses **iodine-based contrast agents**, not gadolinium, to visualize blood vessels. - Iodine contrast agents work by absorbing X-rays, making blood vessels appear bright on CT images. *Bronchography* - **Bronchography** is an older imaging technique that involved introducing an **iodinated contrast medium** directly into the bronchial tree. - It has largely been replaced by **high-resolution CT scans** for evaluating airways. *Contrast Sonography* - **Contrast-enhanced ultrasound (CEUS)**, or contrast sonography, primarily uses **microbubble contrast agents** made of inert gas. - These microbubbles enhance the reflectivity of blood, improving visualization of blood flow and organ perfusion.
Question 2: What is the diagnosis for this patient with end-stage renal disease who developed skin changes after an imaging procedure?
- A. Porphyria cutanea tarda
- B. Nephrogenic systemic fibrosis (Correct Answer)
- C. Calciphylaxis
- D. Actinic elastosis
Explanation: **Nephrogenic systemic fibrosis** * This condition is strongly associated with exposure to **gadolinium-based contrast agents** in patients with severe **renal insufficiency** or **end-stage renal disease (ESRD)**. * It presents with **skin thickening** and hardening, often involving the extremities and trunk, which can progress to joint contractures and immobility. *Porphyria cutanea tarda* * This is a **disorder of heme synthesis** characterized by **fragile skin**, **blistering**, and **hypertrichosis** in sun-exposed areas [1]. * While it can be associated with liver disease and sometimes seen in patients with ESRD, it is not directly linked to contrast media exposure [1]. *Calciphylaxis* * This severe and rare syndrome involves **vascular calcification** and **skin necrosis**, predominantly seen in patients with ESRD. * It typically presents as painful, violaceous skin lesions that progress to ulcers, and while connected to ESRD, it is not triggered by imaging procedures. *Actinic elastosis* * This condition refers to **degeneration of elastic tissue in the skin** due to chronic and excessive **sun exposure**. * It is characterized by thickened, wrinkled, and yellowed skin and is not related to kidney disease or contrast agent exposure.
Question 3: Most specific test for diagnosing Fabry disease on kidney biopsy?
- A. Silver stain
- B. H&E stain
- C. PAS stain
- D. Electron microscopy (Correct Answer)
Explanation: ***Electron microscopy*** - **Electron microscopy** is the most specific test as it can visualize the characteristic **lamellated zebra bodies** (lysosomal inclusions of globotriaosylceramide) in various cell types, including podocytes, which are pathognomonic for Fabry disease. - While other stains might show lipid accumulation, EM provides the definitive ultrastructural evidence by identifying the specific morphology of the accumulated glycosphingolipids. *Silver stain* - **Silver stains** are primarily used to highlight **reticular fibers**, basement membranes, or certain microorganisms, and are not specific for the lipid inclusions seen in Fabry disease. - They would not differentiate Fabry inclusions from other forms of cellular deposits or normal cellular components. *H&E stain* - **Hematoxylin and Eosin (H&E) stain** is a general histological stain that can show enlarged podocytes or vacuolization in Fabry disease, but these findings are **non-specific** and can be seen in other conditions. - H&E does not specifically highlight the characteristic lysosomal lipid inclusions. *PAS stain* - **Periodic Acid-Schiff (PAS) stain** detects **carbohydrates** and mucosubstances and may stain some of the accumulated glycosphingolipids with variable intensity. - However, PAS staining is not specific for the diagnosis of Fabry disease, as other conditions can also show PAS-positive material, and it does not reveal the characteristic lamellated structure of the inclusions.
Question 4: A renal biopsy shows 'bamboo spine' pattern in arterioles. Which immunofluorescence finding would best support thrombotic microangiopathy?
- A. Mesangial IgA deposits
- B. Linear IgG deposits
- C. Granular C3 deposits
- D. Minimal/negative immunofluorescence staining (Correct Answer)
Explanation: ***Minimal/negative immunofluorescence staining*** - Thrombotic microangiopathy (TMA) is characterized by **thrombi** in arterioles and capillaries, leading to **ischemic injury** and **fibrin deposition**, but typically lacks significant immune complex deposition [3]. - Therefore, immunofluorescence in TMA often shows **negative** or only very subtle, non-specific staining for immunoglobulins and complement components, which helps differentiate it from immune-mediated glomerular diseases [3]. *Mesangial IgA deposits* - This finding is characteristic of **IgA nephropathy**, a primary glomerular disease, not typically associated with the 'bamboo spine' pattern of arteriolar thrombi seen in TMA. - IgA nephropathy involves immune complex deposition in the **mesangium**, leading to hematuria and proteinuria. *Linear IgG deposits* - **Linear IgG deposits** on the glomerular basement membrane are the hallmark of **Goodpasture syndrome** (anti-GBM disease), an autoimmune condition causing rapidly progressive glomerulonephritis [1]. - This is distinct from TMA, which involves microvascular thrombosis, not anti-GBM antibodies [3]. *Granular C3 deposits* - **Granular C3 deposits**, often with IgG or IgM, are classic findings in various forms of **immune complex-mediated glomerulonephritis** (e.g., post-infectious glomerulonephritis, lupus nephritis) [1]. - While complement activation can occur in some TMAs, prominent granular C3 deposition is more suggestive of immune complex disease rather than the primary thrombotic process of TMA [2]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 526-527. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 534-535. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 540-541.
Question 5: Which of the following indicates radiograph contrast induced nephropathy?
- A. Decreased urine output
- B. Increased bilirubin
- C. Increased creatinine levels (Correct Answer)
- D. Decreased bilirubin
Explanation: ***Increased creatinine levels*** - **Contrast-induced nephropathy (CIN)** is defined as an abrupt increase in **serum creatinine** following the intravascular administration of contrast material [1]. - A typical increase is defined as an absolute increase in serum creatinine of at least 0.3 mg/dL (26.5 µmol/L) or a 50% relative increase from baseline within 48-72 hours. *Decreased urine output* - While a **decreased urine output** (oliguria) can be a symptom of acute kidney injury, it is not the primary diagnostic criterion for **contrast-induced nephropathy**. - The diagnosis of CIN relies more specifically on changes in **renal function markers** like creatinine, rather than just urine volume [1]. *Increased bilirubin* - **Increased bilirubin** levels typically indicate **liver dysfunction** or **hemolysis**, not necessarily kidney injury. - There is no direct causal link between contrast media administration and elevated bilirubin as a marker of acute kidney damage. *Decreased bilirubin* - **Decreased bilirubin** levels are not associated with any form of organ damage and generally hold no clinical significance. - This finding would not indicate **contrast-induced nephropathy** or any other common pathology.
Question 6: GFR for assessment of impaired renal function is best measured by
- A. MAG3
- B. IodoHippurate
- C. DTPA (Correct Answer)
- D. DMSA Scan
Explanation: ***DTPA*** - **Diethylene Triamine Pentaacetic Acid (DTPA)** is the primary radiopharmaceutical used to measure **glomerular filtration rate (GFR)**, which is the gold standard for quantifying renal function. - DTPA is freely filtered by the glomeruli and not reabsorbed or secreted by the tubules, making it an excellent tracer for evaluating glomerular function and assessing the degree of renal impairment. - **Note:** While MAG3 is often preferred for dynamic renal imaging in patients with severe renal impairment (GFR < 30 ml/min) due to better image quality, DTPA remains the standard for direct GFR measurement. *MAG3* - **Mercaptoacetyltriglycine (MAG3)** is used to assess **effective renal plasma flow (ERPF)** and tubular secretion, not GFR. - MAG3 is actually preferred over DTPA for dynamic renal scintigraphy in patients with poor renal function because of its superior extraction efficiency and image quality. - However, it does not directly measure GFR, which is the primary parameter for quantifying impaired renal function. *IodoHippurate* - **IodoHippurate** (I-123 or I-131 labeled) is used to measure **effective renal plasma flow (ERPF)** through tubular secretion. - While it provides information about renal blood flow, it does not directly measure GFR and is not the primary agent for assessing the degree of renal functional impairment. *DMSA Scan* - **Dimercaptosuccinic acid (DMSA)** is used for **static cortical imaging** to assess renal parenchymal structure and detect abnormalities like renal scarring, differential renal function, or pyelonephritis. - DMSA binds to the proximal tubular cells and provides anatomical information, but does not assess dynamic renal function or measure GFR.
Question 7: At what glomerular filtration rate (GFR) is the term "end-stage renal disease (ESRD)" typically classified?
- A. less than 15% of normal (Correct Answer)
- B. 10%—25% of normal
- C. 15%—25% of normal
- D. 5%—10% of normal
Explanation: ***Less than 15% of normal*** - **End-stage renal disease (ESRD)** is defined by a **glomerular filtration rate (GFR)** that falls below **15 mL/min/1.73 m²**, which is approximately **less than 15% of normal function**. - At this stage, **renal replacement therapy** (dialysis or transplantation) is typically required to sustain life. *15%—25% of normal* - This GFR range (15-25 mL/min/1.73 m²) corresponds to **Stage 4 chronic kidney disease (CKD)**, which is severe but not yet formally "end-stage." - Patients in this stage require careful monitoring and management, but may not immediately need renal replacement therapy. *10%—25% of normal* - This range overlaps with both **severe CKD (Stage 4)** and the beginning of **ESRD (Stage 5)**, but it is not the precise definition for ESRD. - The critical threshold for ESRD is uniformly established as GFR below 15 mL/min/1.73 m². *5%—10% of normal* - While a GFR in this range certainly indicates **ESRD**, the official classification includes any GFR **below 15% of normal** (or below 15 mL/min/1.73 m²), making "less than 15%" the most accurate and inclusive answer. - This smaller range describes a more advanced state within ESRD, but not the general definition.
Question 8: All of the following are used in a patient with decreased renal function (reduced GFR) to avoid contrast nephropathy except?
- A. N-acetyl cysteine
- B. Mannitol (Correct Answer)
- C. Fenoldopam
- D. Low osmolar contrast media (LOCM)
Explanation: **Explanation:** Contrast-Induced Nephropathy (CIN) is a significant risk in patients with reduced GFR. The goal of management is to minimize renal vasoconstriction and oxidative stress. **Why Mannitol is the Correct Answer:** Historically, diuretics like **Mannitol** and Furosemide were thought to "flush" the kidneys. However, clinical trials (such as the PRINCE study) have shown that Mannitol is **ineffective** and may actually be **harmful**. It can cause osmotic diuresis leading to dehydration and further renal vasoconstriction, potentially worsening the risk of CIN. Therefore, it is no longer recommended. **Analysis of Other Options:** * **N-acetyl cysteine (NAC):** An antioxidant that scavenges free radicals and induces vasodilation. While its efficacy is debated in recent large trials (PRESERVE), it is still traditionally used in protocols to prevent CIN due to its low cost and safety profile. * **Fenoldopam:** A selective dopamine D1 receptor agonist that causes renal vasodilation. Though not routinely used due to cost and mixed evidence, it is pharmacologically intended to increase renal blood flow. * **Low Osmolar Contrast Media (LOCM):** High osmolar contrast (HOCM) is highly nephrotoxic. Switching to LOCM (e.g., Iohexol) or Iso-osmolar contrast (e.g., Iodixanol) significantly reduces the risk of CIN in high-risk patients. **High-Yield Clinical Pearls for NEET-PG:** * **Most effective preventive measure:** Adequate **Pre-procedure Hydration** with 0.9% Normal Saline is the gold standard. * **Definition of CIN:** An increase in serum creatinine of >0.5 mg/dL or >25% from baseline within 48–72 hours of contrast administration. * **Metformin:** Must be withheld for 48 hours *after* the procedure to avoid lactic acidosis if renal failure occurs.
Question 9: Which of the following conditions is associated with contrast nephropathy?
- A. Diabetes nephropathy (Correct Answer)
- B. Hypertension
- C. Malignant hypertension
- D. Hypertensive glomerulosclerosis
Explanation: **Explanation:** **Contrast-Induced Nephropathy (CIN)** is defined as an acute impairment of renal function (an increase in serum creatinine by >25% or >0.5 mg/dL) occurring within 48–72 hours of intravascular contrast administration. **Why Diabetes Nephropathy is the Correct Answer:** Diabetes mellitus, particularly when associated with pre-existing renal insufficiency (**Diabetic Nephropathy**), is the **single most significant independent risk factor** for developing CIN. The pathophysiology involves contrast-induced renal vasoconstriction leading to medullary ischemia and direct tubular cytotoxicity. In diabetic patients, the baseline oxidative stress and impaired vasodilatory capacity of the renal vasculature significantly potentiate these effects. **Analysis of Incorrect Options:** * **B, C, and D (Hypertension, Malignant Hypertension, Hypertensive Glomerulosclerosis):** While chronic hypertension can lead to renal damage, it is generally considered a secondary risk factor. Hypertension only significantly increases the risk of CIN if it has already progressed to significant **chronic kidney disease (CKD)** with a reduced Glomerular Filtration Rate (GFR). Diabetic nephropathy carries a much higher relative risk compared to hypertensive nephrosclerosis alone. **High-Yield Clinical Pearls for NEET-PG:** * **Most Important Risk Factor:** Pre-existing renal insufficiency (low GFR). * **Most Effective Prophylaxis:** Intravenous hydration with **Isotonic Saline (0.9% NaCl)** or Sodium Bicarbonate before and after the procedure. * **Metformin Warning:** Metformin does not cause CIN, but if CIN occurs, Metformin can accumulate and cause **Lactic Acidosis**. It should be withheld for 48 hours after contrast administration. * **Contrast Choice:** Non-ionic, **iso-osmolar** contrast media (e.g., Iodixanol) carry the lowest risk for nephropathy.
Question 10: Which of the following investigations must be performed before administering contrast to a patient?
- A. Kidney function test (KFT) (Correct Answer)
- B. Liver function test (LFT)
- C. Urine specific gravity
- D. Serum electrolytes
Explanation: **Explanation:** The administration of iodinated contrast media (used in CT scans and angiography) poses a significant risk of **Contrast-Induced Nephropathy (CIN)**. CIN is defined as an acute decline in renal function (increase in serum creatinine by >0.5 mg/dL or >25% from baseline) within 48–72 hours of contrast exposure. Therefore, assessing the **Kidney Function Test (KFT)**—specifically **Serum Creatinine** and the **estimated Glomerular Filtration Rate (eGFR)**—is mandatory to screen for pre-existing renal impairment, which is the strongest risk factor for CIN. **Analysis of Incorrect Options:** * **Liver Function Test (LFT):** While some contrast agents are excreted via the biliary system, hepatic impairment does not significantly increase the risk of acute toxicity or contrast reactions. * **Urine Specific Gravity:** This measures urine concentration and hydration status but is an unreliable indicator of the kidney's ability to clear contrast media compared to eGFR. * **Serum Electrolytes:** While important for general patient management, electrolyte imbalances are not a direct contraindication to contrast nor a primary predictor of contrast-induced injury. **High-Yield Clinical Pearls for NEET-PG:** * **Safe Threshold:** Contrast is generally considered safe if **eGFR >60 mL/min/1.73m²**. Caution is required if eGFR is between 30–60, and it is generally avoided (unless emergency) if **eGFR <30**. * **Prevention:** The most effective preventive measure for CIN is **intravenous hydration** with 0.9% Normal Saline before and after the procedure. * **Metformin:** In patients with renal impairment, Metformin should be withheld for 48 hours after contrast administration to prevent **Lactic Acidosis**. * **MRI Contrast:** For Gadolinium-based agents, the concern is **Nephrogenic Systemic Fibrosis (NSF)** in patients with severe renal failure.
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