Nephrology Practice Questions

Q: Which of the following is the commonest cause of salt-wasting nephropathy?

Analgesic (NSAID) misuse. ### Explanation **Salt-wasting nephropathy** refers to a group of renal disorders where the kidney fails to reabsorb sodium despite normal adrenal function, leading to hyponatremia and volume depletion. [1] **Why Analgesic Misuse is Correct:** The primary site for sodium reabsorption is the renal tubule. [1] Salt-wasting occurs predominantly in **Tubulointerstitial Diseases**. Chronic misuse of NSAIDs or analgesics leads to **Analgesic Nephropathy**, characterized by chronic interstitial nephritis and papillary necrosis. The damage to the medullary interstitium and distal tubules impairs the sodium-reabsorbing capacity and the counter-current mechanism, making it the most common clinical cause of salt-wasting among the given options. **Analysis of Incorrect Options:** * **Amyloidosis:** Primarily affects the glomerulus (causing nephrotic syndrome). [2] While it can involve the interstitium in advanced stages, it is not the classic or most common cause of salt-wasting. * **Grommets Disease:** This is a distracter term (Grommets are ventilation tubes used in the ear for Otitis Media with Effusion) and is not a recognized renal pathology. * **Systemic Lupus Erythematosus (SLE):** While SLE (Lupus Nephritis) can involve the tubules, it typically presents as a **Glomerulonephritis** (proteinuria, hematuria, and hypertension) rather than a primary salt-wasting tubulopathy. **NEET-PG High-Yield Pearls:** * **Common Causes of Salt-Wasting:** Chronic Pyelonephritis, Medullary Cystic Disease, Polycystic Kidney Disease (PKD), and Analgesic Nephropathy. * **Clinical Presentation:** Patients often present with "normotensive" or hypotensive states despite renal failure, polyuria, and a craving for salt. * **Distinction:** Do not confuse salt-wasting nephropathy with Addison’s disease; in nephropathy, aldosterone levels are usually elevated (secondary hyperaldosteronism) as the body attempts to compensate for renal sodium loss. [1]

Q: Which of the following has no role in the treatment of dangerous hyperkalemia?

Intravenous sodium bicarbonate. In the management of life-threatening hyperkalemia, the goal is to stabilize the myocardium, shift potassium intracellularly, and enhance elimination [1]. **Explanation of the Correct Answer:** **D. Intravenous Sodium Bicarbonate:** Current clinical guidelines (such as AHA and KDIGO) state that sodium bicarbonate has **no role** in the acute, emergency management of hyperkalemia, especially when used as a monotherapy. It does not lower potassium levels rapidly or reliably in patients without metabolic acidosis. While it may be used in cases of severe pre-existing metabolic acidosis (pH < 7.2), it is no longer considered a first-line treatment for "dangerous" hyperkalemia. **Why the other options are wrong (They ARE used):** * **A. Intravenous Calcium Chloride/Gluconate:** This is the first step in treatment [1]. It **stabilizes the cardiac membrane** by antagonizing the effects of potassium on the resting membrane potential, preventing arrhythmias. It does *not* lower serum potassium. * **B. Salbutamol:** This is a $\beta_2$-agonist that stimulates the Na+/K+-ATPase pump, causing an **intracellular shift** of potassium. It is a rapid-acting temporizing measure. * **C. Hemodialysis:** This is the **most definitive and effective** method for potassium removal, especially in patients with renal failure or those refractory to medical therapy. **High-Yield Clinical Pearls for NEET-PG:** * **The "Rule of 10":** Calcium gluconate (10 ml of 10% solution) is preferred over Calcium chloride because it is less caustic to peripheral veins [1]. * **Insulin-Glucose:** 10 units of IV regular insulin with 50g of 25-50% Dextrose is the most reliable method to shift potassium intracellularly. * **ECG Changes:** The earliest sign is **Tall Tented T-waves**, followed by PR prolongation, loss of P-waves, and finally the **Sine Wave pattern**, which precedes cardiac arrest.

Q: Which of the following is NOT a cause of rapidly progressive glomerulonephritis?

Rheumatoid arthritis. Rapidly Progressive Glomerulonephritis (RPGN) is a clinical syndrome characterized by a rapid decline in GFR (usually >50% within weeks to months) and the histological hallmark of **crescent formation** in the majority of glomeruli [1]. **Explanation of the Correct Answer:** * **Option D (Rheumatoid Arthritis):** While RA is a systemic inflammatory disease, it is **not** a recognized cause of RPGN. Renal involvement in RA is typically due to secondary amyloidosis (AA type), membranous nephropathy (often drug-induced by gold or penicillamine), or analgesic nephropathy. It does not typically manifest as a crescentic, rapidly declining glomerulonephritis. **Explanation of Incorrect Options:** * **Option A (SLE):** Lupus Nephritis (specifically Class IV - Diffuse Proliferative GN) is a classic cause of **Type II (Immune-complex mediated) RPGN** [1]. * **Option B (Polyarteritis nodosa):** Although classic PAN involves medium-sized vessels and often spares the glomueruli, it is frequently grouped with systemic vasculitides that cause **Type III (Pauci-immune) RPGN** [1]. Note: Microscopic Polyangiitis (MPA) is a more common cause of RPGN than classic PAN. * **Option C (PSGN):** While most cases of PSGN resolve spontaneously, a small percentage (approx. 1-3%) can progress to a "crescentic" phase, leading to RPGN [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Classification of RPGN:** 1. **Type I (Anti-GBM):** Goodpasture syndrome (Linear IgG deposits) [1]. 2. **Type II (Immune Complex):** SLE, PSGN, IgA Nephropathy, Henoch-Schönlein Purpura (Lumpy-bumpy/Granular deposits) [1]. 3. **Type III (Pauci-immune):** Wegener’s (GPA), Microscopic Polyangiitis, Churg-Strauss (ANCA associated; little to no immune deposits) [1]. * **Histology:** The "crescents" are formed by the proliferation of **parietal epithelial cells** and the migration of monocytes/macrophages into Bowman’s space.

Q: A 68-year-old man weighing 60 kg has a plasma creatinine of 3 mg/dL. What is his estimated creatinine clearance?

20 mL/min. To calculate the estimated Creatinine Clearance (eCrCl) in a clinical setting, the **Cockcroft-Gault formula** is the gold standard for exam purposes. ### **Calculation using Cockcroft-Gault Formula:** The formula is: $\text{CrCl (mL/min)} = \frac{(140 - \text{Age}) \times \text{Weight (kg)}}{72 \times \text{Plasma Creatinine (mg/dL)}}$ *Note: For females, multiply the result by 0.85.* **Plugging in the values:** $\text{CrCl} = \frac{(140 - 68) \times 60}{72 \times 3}$ $\text{CrCl} = \frac{72 \times 60}{72 \times 3}$ $\text{CrCl} = \frac{60}{3} = \mathbf{20 \text{ mL/min}}$ ### **Analysis of Options:** * **Option B (20 mL/min):** This is the correct value derived from the standard formula. * **Options A, C, and D:** These are incorrect as they do not align with the mathematical calculation. A common error is forgetting to include the "72" constant or miscalculating the age factor (140 - 68 = 72). ### **NEET-PG High-Yield Pearls:** 1. **Formula Variables:** Remember that CrCl is **directly proportional** to body weight and **inversely proportional** to age and serum creatinine. 2. **Gender Adjustment:** Always check the gender in the clinical vignette. If this patient were female, the answer would be $20 \times 0.85 = 17 \text{ mL/min}$. 3. **Limitations:** The Cockcroft-Gault formula overestimates GFR because creatinine is not only filtered by the glomerulus but also secreted by the proximal tubules [1]. 4. **CKD Staging:** A CrCl of 20 mL/min places this patient in **Stage 4 Chronic Kidney Disease** (Severely decreased GFR: 15–29 mL/min).

Q: Which of the following is NOT typically seen in cystitis?

Fever. **Explanation:** The clinical differentiation between **Lower Urinary Tract Infection (Cystitis)** and **Upper Urinary Tract Infection (Pyelonephritis)** is a high-yield concept for NEET-PG. **1. Why Fever is the Correct Answer:** Cystitis is a localized mucosal inflammation of the bladder. It is typically **afebrile** because the infection is confined to the bladder surface and does not involve the renal parenchyma or systemic circulation. The presence of high-grade fever, chills, and rigors strongly suggests that the infection has ascended to the kidneys (Acute Pyelonephritis) or has resulted in bacteremia [1]. [2] **2. Analysis of Incorrect Options:** * **Dysuria (Option C):** This is the hallmark symptom of cystitis, caused by the irritation of the urethral and bladder mucosal lining during micturition. * **Nocturia (Option D) and Frequency:** Inflammation of the bladder wall (detrusor muscle) leads to decreased bladder capacity and increased irritability, resulting in the frequent urge to void during the day and night. * **Hematuria (Option B):** Gross or microscopic hematuria occurs due to the friability of the inflamed bladder mucosa [3]. When present with dysuria, it is often termed "hemorrhagic cystitis." **Clinical Pearls for NEET-PG:** * **The "Triad" of Cystitis:** Dysuria, Frequency, and Urgency. * **Pyelonephritis Indicators:** Fever, flank pain (CVA tenderness), and nausea/vomiting [2]. * **Most Common Pathogen:** *E. coli* remains the leading cause of both cystitis and pyelonephritis [2]. * **Sterile Pyuria:** If a patient has symptoms of cystitis but negative routine cultures, consider *Chlamydia trachomatis* or *Neisseria gonorrhoeae* [1].

Q: Hereditary nephritis is seen in:

Alport syndrome. **Explanation:** **Alport Syndrome** is the correct answer as it is a classic example of **hereditary nephritis** [1]. It is primarily an X-linked dominant disorder (85% of cases) caused by mutations in the genes encoding the **alpha-chains of Type IV collagen** (specifically COL4A3, COL4A4, and COL4A5) [1]. Type IV collagen is a structural component of the basement membranes in the kidney, ears, and eyes. Clinically, it presents with a triad of progressive hematuria (leading to ESRD), sensorineural hearing loss, and ocular abnormalities (e.g., anterior lenticonus). **Analysis of Incorrect Options:** * **Analgesic Nephropathy:** This is an **acquired** chronic interstitial nephritis caused by the long-term overuse of pain medications (e.g., phenacetin, NSAIDs). It is characterized by renal papillary necrosis. * **Balkan Nephropathy:** This is an **environmentally induced** chronic tubulointerstitial nephritis found in the Danube River basin [3]. It is linked to the ingestion of **aristolochic acid** from seeds of the *Aristolochia clematitis* plant [3]. * **Eosinophilic Nephritis:** This is typically a manifestation of **Acute Interstitial Nephritis (AIN)**, most commonly a hypersensitivity reaction to drugs (e.g., NSAIDs, antibiotics like Penicillin). It is an immunologic, not hereditary, condition. **High-Yield Clinical Pearls for NEET-PG:** * **Electron Microscopy (EM) Finding:** The pathognomonic feature of Alport Syndrome is the **"Basket-weave appearance"** (irregular thickening, thinning, and splitting of the Glomerular Basement Membrane) [1]. * **Thin Basement Membrane Disease (TBMD):** Also known as Benign Familial Hematuria; it is a differential for Alport but has a much better prognosis. * **Goodpasture Syndrome vs. Alport:** While both involve Type IV collagen, Goodpasture is an *autoimmune* attack against the alpha-3 chain [2], whereas Alport is a *genetic* defect [1].

Q: A female patient presents with an upper respiratory tract infection. Two days later, she develops hematuria. What is the probable diagnosis?

IgA nephropathy. ### Explanation **Correct Answer: A. IgA nephropathy** The clinical hallmark of **IgA nephropathy (Berger’s disease)** is **synpharyngitic hematuria** [1]. This refers to the onset of gross hematuria occurring simultaneously or within 1–3 days of an upper respiratory tract infection (URTI) [1]. The underlying mechanism involves the overproduction of galactose-deficient IgA1 in response to mucosal triggers, which forms immune complexes that deposit in the glomerular mesangium, causing inflammation [1]. **Why the other options are incorrect:** * **Poststreptococcal glomerulonephritis (PSGN):** This is the most common differential. However, PSGN has a **latent period** of 1–3 weeks after a sore throat (pharyngitis) or 3–6 weeks after a skin infection (impetigo). It is associated with low C3 complement levels, whereas IgA nephropathy typically has normal complement levels. * **Henoch-Schönlein Purpura (HSP):** While HSP shares the same pathology as IgA nephropathy (IgA vasculitis), it is a systemic disease. Diagnosis requires extra-renal manifestations like palpable purpura (usually on lower limbs), arthralgia, and abdominal pain. * **Wegener’s Granulomatosis (GPA):** This is a small-vessel vasculitis characterized by involving the upper/lower respiratory tract (sinusitis, lung nodules) and kidneys (RPGN). It is associated with c-ANCA (PR3) positivity and does not typically present as immediate post-URTI hematuria. **High-Yield Clinical Pearls for NEET-PG:** * **Most common** cause of primary glomerulonephritis worldwide. * **Complement levels:** Characteristically **normal** (unlike PSGN, Lupus, or MPGN). * **Prognostic Marker:** Persistent proteinuria (>1g/day) is the most important predictor of progression to ESRD. * **Association:** Frequently associated with Celiac disease and Liver cirrhosis (decreased clearance of IgA complexes).

Question 1

Which of the following is the commonest cause of salt-wasting nephropathy?

Accepted Answer

Analgesic (NSAID) misuse

Answer

Amyloidosis

Answer

Grommets disease

Answer

Systemic Lupus Erythematosus (SLE)

Question 2

What is the most specific marker of renal function?

Accepted Answer

Serum creatinine

Answer

Creatinine clearance

Answer

Insulin clearance

Answer

Blood urea

Question 3

A patient presents with acute renal failure (ARF) and complete anuria. An ultrasound shows normal findings. What is the next appropriate investigation?

Accepted Answer

Radio renogram

Answer

Intravenous pyelography (IVP)

Answer

Antegrade pyelography

Answer

Retrograde pyelography

Question 4

Which of the following has no role in the treatment of dangerous hyperkalemia?

Accepted Answer

Intravenous sodium bicarbonate

Answer

Intravenous calcium chloride

Answer

Salbutamol

Answer

Hemodialysis

Question 5

Which of the following is NOT a cause of rapidly progressive glomerulonephritis?

Accepted Answer

Rheumatoid arthritis

Answer

Systemic Lupus Erythematosus (SLE)

Answer

Polyarteritis nodosa

Answer

Post-streptococcal glomerulonephritis

Question 6

A 68-year-old man weighing 60 kg has a plasma creatinine of 3 mg/dL. What is his estimated creatinine clearance?

Accepted Answer

20 mL/min

Answer

10 mL/min

Answer

30 mL/min

Answer

40 mL/min

Question 7

Which of the following is NOT typically seen in cystitis?

Accepted Answer

Fever

Answer

Hematuria

Answer

Dysuria

Answer

Nocturia

Question 8

All of the following factors are associated with adverse prognosis and high risk of renal progression in Lupus Nephritis, EXCEPT:

Accepted Answer

Anti-LA (SSB)

Answer

High levels of Anti-ds DNA

Answer

Persistent proteinuria (nephrotic range > 3 gm/day)

Answer

Hypocomplementenemia

Question 9

Hereditary nephritis is seen in:

Accepted Answer

Alport syndrome

Answer

Analgesic nephropathy

Answer

Balkan nephropathy

Answer

Eosinophilic nephritis

Question 10

A female patient presents with an upper respiratory tract infection. Two days later, she develops hematuria. What is the probable diagnosis?

Accepted Answer

IgA nephropathy

Answer

Wegener's granulomatosis

Answer

Henoch-Schonlein purpura

Answer

Poststreptococcal glomerulonephritis

Nephrology — MCQs

Nephrology — MCQs

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