Nephrology Practice Questions

Q: Retroperitoneal fibrosis most commonly presents with?

Back pain. **Explanation:** **Retroperitoneal Fibrosis (Ormond’s Disease)** is characterized by the proliferation of aberrant fibro-inflammatory tissue in the retroperitoneum, typically centered around the infrarenal abdominal aorta and iliac arteries. **Why Back Pain is the Correct Answer:** Dull, poorly localized **back or flank pain** is the most common presenting symptom, occurring in over 80–90% of patients. The pain is typically insidious in onset, non-colicky, and results from the mass effect of the fibrotic plaque or the entrapment of retroperitoneal sensory nerves. It often radiates to the lower abdomen or groins. **Analysis of Incorrect Options:** * **Ureteric Obstruction (Option C):** While ureteric involvement is the most common *complication* and a hallmark of the disease (leading to hydronephrosis and renal failure), it is usually a consequence of the disease progression rather than the initial presenting symptom. Patients often present with pain long before obstructive uropathy becomes clinically evident. * **Pedal Edema (Option A):** This occurs due to the compression of the inferior vena cava (IVC) or lymphatic vessels by the fibrotic mass. While a known feature, it is less frequent than back pain. * **Ascites (Option B):** This is an uncommon presentation and usually suggests advanced portal vein involvement or secondary systemic causes, which are rare in isolated retroperitoneal fibrosis. **High-Yield Clinical Pearls for NEET-PG:** * **Etiology:** 70% are idiopathic; others are associated with drugs (Methysergide, Ergotamine, Beta-blockers) or **IgG4-related disease**. * **Imaging:** CT/MRI shows a "mantle-like" mass encasing the aorta. A classic finding on IVP is **medial deviation of the ureters**. * **Treatment:** Corticosteroids are the first-line medical management; Tamoxifen or Mycophenolate Mofetil are used in refractory cases. Ureterolysis is the surgical intervention of choice.

Q: Dialysis allows for the exchange of particles across a semipermeable membrane by which of the following actions?

Osmosis and diffusion. **Explanation:** Dialysis is a life-sustaining process used in renal failure to remove metabolic waste products and excess fluid from the blood [1], [4]. It relies on the movement of solutes and solvents across a semipermeable membrane based on two primary physical principles: 1. **Diffusion:** This is the movement of **solutes** (such as urea, creatinine, and potassium) from an area of higher concentration (blood) to an area of lower concentration (dialysate) across the membrane [1], [4]. 2. **Osmosis:** This is the movement of **solvent (water)** across the membrane from an area of lower solute concentration to an area of higher solute concentration [2]. In hemodialysis, fluid removal is further enhanced by **ultrafiltration** (hydrostatic pressure), while in peritoneal dialysis, osmotic gradients are created using glucose [1]. **Analysis of Incorrect Options:** * **Option B:** This is incorrect because fluid (water) moves toward a solution with a **higher** solute concentration (osmosis), not lower [2]. * **Option C:** The semipermeable membrane is designed to be selective. It prevents the loss of essential large molecules like **albumin (proteins)** and **blood cells**, allowing only small solutes and water to pass. * **Option D:** Solute particles move toward a solution with a **lower** concentration (diffusion) to achieve equilibrium, not higher [4]. **High-Yield Clinical Pearls for NEET-PG:** * **Efficiency:** Diffusion is most efficient for small molecules (Urea < Creatinine < Phosphate). * **Convection:** In techniques like Hemofiltration, "solvent drag" (convection) is used to remove larger middle molecules (e.g., $̢β_2$-microglobulin) [3]. * **Dialysate Composition:** To prevent the removal of essential electrolytes, the dialysate concentration of substances like Calcium and Bicarbonate is kept similar to or higher than normal plasma levels [4].

Q: Which of the following is NOT a complication of hemodialysis?

Hypertension. The correct answer is **C. Hypertension**. In fact, **hypotension** is the most common acute complication of hemodialysis, occurring in approximately 20–30% of sessions. **Why Hypertension is the correct answer:** While chronic hypertension is a common reason patients *require* dialysis, the procedure itself typically causes a drop in blood pressure due to rapid fluid removal (ultrafiltration) and shifts in serum osmolality. While "intradialytic hypertension" can occur in a small subset of patients (due to renin-angiotensin activation or sympathetic overactivity), it is considered a paradoxical event rather than a standard expected complication of the procedure [1]. **Analysis of Incorrect Options:** * **A. Altered cardiovascular dynamics:** Hemodialysis causes significant shifts in blood volume and electrolytes. This leads to decreased cardiac output, arrhythmias, and potential myocardial "stunning" due to transient ischemia during fluid removal. * **B. Anaphylactoid reaction:** This is a known acute complication, often referred to as "First-use syndrome." It is typically caused by hypersensitivity to the dialyzer membrane (e.g., cuprophane) or sterilizing agents like ethylene oxide. * **D. Muscle cramps:** These are very common (5–20% of sessions). The etiology is multifactorial, involving rapid fluid removal, tissue hypoxia, and electrolyte imbalances (hypomagnesemia or hypocalcemia) [1]. **High-Yield NEET-PG Pearls:** * **Most common acute complication:** Hypotension. * **Disequilibrium Syndrome:** Caused by rapid removal of urea, leading to cerebral edema. Symptoms include headache, confusion, and seizures. Prevented by slow initial dialysis. * **First-use Syndrome:** Type A (Anaphylactic, IgE-mediated) occurs within minutes; Type B (Non-specific, chest/back pain) occurs later in the session. * **Commonest cause of death in ESRD patients on dialysis:** Cardiovascular disease (Arrhythmias/MI).

Q: All are true about Alport syndrome, EXCEPT:

Renal failure occurs in 50% of affected males. Explanation: Alport Syndrome is a hereditary basement membrane disorder caused by mutations in the genes encoding the Type IV collagen alpha chains (α3, α4, or α5) [2]. Why Option D is the correct answer (The Exception): In the most common form, X-linked Alport Syndrome (XLAS), renal involvement is progressive and severe in males. It is not limited to 50%; rather, virtually 100% of affected males will develop End-Stage Renal Disease (ESRD) by the age of 40. The 50% figure is inaccurate as it significantly underestimates the penetrance and severity of the disease in males. Analysis of other options: * Option A (Hereditary nephropathy): True. It is the most common hereditary glomerular disease, most frequently inherited in an X-linked dominant pattern (85%), followed by autosomal recessive and dominant forms. * Option B (Sensorineural hearing loss): True. This is a classic extra-renal manifestation. It is typically bilateral, high-frequency, and usually manifests during late childhood or adolescence. * Option C (Microscopic hematuria): True. Persistent microscopic hematuria is the earliest and most common sign of Alport syndrome, often appearing in early childhood. NEET-PG High-Yield Pearls: * Pathology: Electron microscopy shows a characteristic "Basket-weave appearance" due to irregular thickening, thinning, and splitting of the Glomerular Basement Membrane (GBM) [2]. * Ocular Findings: Anterior Lenticonus (pathognomonic) and "dot-and-fleck" retinopathy. * Molecular Defect: Mutation in COL4A5 (X-linked) or COL4A3/COL4A4 (Autosomal) [2]. * Post-Transplant Complication: Patients are at risk of developing Anti-GBM disease (Goodpasture-like syndrome) in the graft because their immune system recognizes the normal Type IV collagen in the donor kidney as foreign [1].

Q: Absent P waves with wide QRS complex indicates serum potassium of what level?

More than 8 meq/L. **Explanation:** Hyperkalemia is a critical electrolyte abnormality that causes progressive changes in cardiac conduction [1]. The ECG manifestations follow a predictable sequence as serum potassium levels rise: 1. **Serum K+ 5.5–6.5 mEq/L:** The earliest sign is the appearance of **Tall, peaked T waves** (narrow base, "tent-shaped") in most leads [1]. 2. **Serum K+ 6.5–8.0 mEq/L:** As levels increase, there is paralysis of the atria [1]. This leads to **prolongation of the PR interval**, flattening/decreased amplitude of the P wave, and eventually **disappearance of the P wave**. Concurrently, the **QRS complex begins to widen** [1]. 3. **Serum K+ >8.0 mEq/L:** At this severe level, the P wave is typically **absent**, and the QRS complex becomes **markedly wide**, eventually merging with the T wave to form a **Sine Wave pattern**. This is a pre-terminal rhythm that can rapidly progress to ventricular fibrillation or asystole. **Analysis of Options:** * **Option A (5.4 mEq/L):** This is near the upper limit of normal; ECG is usually normal or shows very mild T-wave peaking. * **Option B (6.5 mEq/L):** At this level, peaked T waves are prominent, but P waves are usually still present, and QRS widening is just beginning. * **Option D (>10 mEq/L):** While ECG changes would be severe here, the classic threshold for the disappearance of P waves and significant QRS widening in medical literature and exams is >8 mEq/L. **Clinical Pearls for NEET-PG:** * **Treatment Priority:** The first step in managing hyperkalemia with ECG changes is **Intravenous Calcium Gluconate** (to stabilize the cardiac membrane), followed by agents to shift K+ intracellularly (Insulin+Dextrose, Salbutamol). * **Pseudohyperkalemia:** Always rule out hemolysis during blood collection if ECG is normal despite high lab values. * **Hypokalemia:** Look for U waves, flattened T waves, and ST depression.

Q: Renal artery stenosis is caused by all of the following except:

Buerger's disease. **Explanation:** Renal Artery Stenosis (RAS) is the narrowing of one or both renal arteries, leading to renovascular hypertension. The correct answer is **Buerger’s disease** because it is a peripheral vascular disease that does not typically involve the renal arteries. **1. Why Buerger’s Disease is the Correct Answer:** Buerger’s disease (Thromboangiitis obliterans) is a non-atherosclerotic, inflammatory occlusive disease that primarily affects **small and medium-sized arteries and veins of the distal extremities** (hands and feet). It is strongly associated with heavy tobacco use. It does not involve visceral arteries like the renal artery. **2. Analysis of Other Options:** * **Atherosclerosis:** The **most common cause** of RAS (approx. 90%), typically involving the proximal third or the ostium of the renal artery. It is usually seen in elderly patients with cardiovascular risk factors. * **Fibromuscular Dysplasia (FMD):** The second most common cause, typically seen in **young females**. It involves the distal two-thirds of the renal artery, often presenting with a "string of beads" appearance on angiography. * **Takayasu Arteritis:** A large-vessel vasculitis ("pulseless disease") that involves the aorta and its primary branches. It is a significant cause of RAS in young patients, particularly in Asian populations. **Clinical Pearls for NEET-PG:** * **Gold Standard Diagnosis:** Digital Subtraction Angiography (DSA). * **Screening Test of Choice:** Duplex Doppler Ultrasound or CT/MR Angiography. * **Classic Sign:** Abdominal bruit heard on auscultation. * **ACE Inhibitor Warning:** ACE inhibitors are contraindicated in **bilateral** renal artery stenosis (or stenosis in a solitary kidney) as they can precipitate acute renal failure by reducing intraglomerular pressure.

Q: What is the definitive treatment for hypermagnesemia?

Hemodialysis. **Explanation:** Hypermagnesemia is a rare but potentially life-threatening electrolyte imbalance, typically occurring in patients with advanced chronic kidney disease (CKD) who ingest magnesium-containing medications. **Why Hemodialysis is the Correct Answer:** While initial management involves stopping magnesium intake and promoting excretion, **Hemodialysis** is the **definitive treatment**. Magnesium is primarily an intracellular cation, but its serum levels are effectively reduced by dialysis because the kidneys are the only natural route for significant magnesium clearance. In patients with severe renal failure or those with life-threatening symptoms (e.g., respiratory depression, coma, or cardiac arrhythmias), dialysis is the only way to rapidly and reliably remove the excess magnesium load from the body [2]. **Analysis of Incorrect Options:** * **A. Calcium Gluconate:** This is the **immediate first-line treatment** for symptomatic hypermagnesemia [1]. It acts as a physiological antagonist to magnesium at the neuromuscular junction and cardiac membrane, protecting the heart. However, it does not remove magnesium from the body; it only stabilizes the membrane. * **B. IV Fluids:** Saline diuresis (with or without loop diuretics) can enhance magnesium excretion in patients with **normal renal function**. It is not definitive in the setting of renal failure. * **C. Exchange Resins:** These (like Sodium Polystyrene Sulfonate) are used for hyperkalemia, not hypermagnesemia. There is no specific exchange resin for magnesium. **High-Yield Clinical Pearls for NEET-PG:** * **Early Sign:** Loss of deep tendon reflexes (DTRs) occurs at levels of 4–6 mEq/L. * **Late Signs:** Respiratory paralysis and heart block occur at levels >10 mEq/L. * **Antidote:** 10% Calcium Gluconate (10 mL IV over 10 mins) [1]. * **Classic Scenario:** An elderly patient with CKD taking magnesium-containing antacids or laxatives.

Question 1

Retroperitoneal fibrosis most commonly presents with?

Accepted Answer

Back pain

Answer

Pedal edema

Answer

Ascites

Answer

Ureteric obstruction

Question 2

Dialysis allows for the exchange of particles across a semipermeable membrane by which of the following actions?

Accepted Answer

Osmosis and diffusion

Answer

Passage of fluid toward a solution with a lower solute concentration

Answer

Allowing the passage of blood cells and protein molecules through it.

Answer

Passage of solute particles toward a solution with a higher concentration.

Question 3

Goodpasture's syndrome is characterized by which of the following?

Accepted Answer

All of the above

Answer

Anti-GBM antibodies

Answer

Crescenteric glomerulonephritis

Answer

Diffuse alveolar haemorrhage

Question 4

Which of the following is NOT a complication of hemodialysis?

Accepted Answer

Hypertension

Answer

Altered cardiovascular dynamics

Answer

Anaphylactoid reaction

Answer

Muscle cramps

Question 5

All are true about Alport syndrome, EXCEPT:

Accepted Answer

Renal failure occurs in 50% of affected males

Answer

Hereditary nephropathy

Answer

Sensorineural hearing loss

Answer

Microscopic hematuria during early childhood

Question 6

What is the most sensitive and specific investigation for screening of renovascular hypertension?

Accepted Answer

Spiral CT Scan

Answer

MRI

Answer

Captopril enhanced radionuclide scan

Answer

Duplex – Doppler flow study

Question 7

Absent P waves with wide QRS complex indicates serum potassium of what level?

Accepted Answer

More than 8 meq/L

Answer

5.4 meq/L

Answer

6.5 meq/L

Answer

More than 10 meq/L

Question 8

Renal artery stenosis is caused by all of the following except:

Accepted Answer

Buerger's disease

Answer

Atherosclerosis

Answer

Fibromuscular dysplasia

Answer

Takayasu arteritis

Question 9

What is the definitive treatment for hypermagnesemia?

Accepted Answer

Hemodialysis

Answer

Calcium gluconate

Answer

IV fluids

Answer

Exchange resins

Question 10

Which of the following conditions is characterized by a normal kidney size?

Accepted Answer

Medullary sponge kidney

Answer

Nephronophthisis

Answer

Autosomal dominant polycystic kidney disease (ADPCKD)

Answer

Acquired renal cysts

Nephrology — MCQs

Nephrology — MCQs

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