Nephrology — MCQs

Nephrology Indian Medical PG Practice Questions and MCQs

Question 261: What are the causes of pulmonary renal syndrome?

A. Leptospirosis
B. Hanta virus
C. Paraquat poisoning
D. All of the above (Correct Answer)

Explanation: No changes made to original text, as provided references did not meet the relevance score threshold for the specific entities described in the question. Pulmonary-Renal Syndrome (PRS) is a clinical entity characterized by the combination of diffuse alveolar hemorrhage (DAH) and glomerulonephritis (GN) [1][2]. While classically associated with autoimmune vasculitides, the term is also used to describe systemic conditions causing simultaneous acute lung injury and acute kidney injury. **Why "All of the Above" is Correct:** * **Leptospirosis (Weil’s Disease):** A classic cause of PRS in the tropics. It presents with the triad of jaundice, acute kidney injury (interstitial nephritis), and pulmonary hemorrhage. * **Hantavirus:** Specifically the Hemorrhagic Fever with Renal Syndrome (HFRS) and Hantavirus Pulmonary Syndrome (HPS) variants can overlap, leading to capillary leak, pulmonary edema/hemorrhage, and acute renal failure. * **Paraquat Poisoning:** This herbicide is highly nephrotoxic and pneumotoxic. It concentrates in the lungs (via polyamine uptake) causing pulmonary fibrosis/hemorrhage and causes acute tubular necrosis (ATN) in the kidneys. **Other Common Causes (Differential Diagnosis):** * **Goodpasture’s Syndrome:** Anti-GBM antibodies (Type II Hypersensitivity) [2]. * **ANCA-associated Vasculitis:** Granulomatosis with Polyangiitis (GPA) and Microscopic Polyangiitis (MPA) [2]. * **Systemic Lupus Erythematosus (SLE):** Lupus nephritis with alveolar hemorrhage [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Investigation of Choice:** To confirm DAH, **Bronchoalveolar Lavage (BAL)** showing progressively bloodier returns is gold standard. * **Serology:** Always check c-ANCA, p-ANCA, and Anti-GBM antibodies in a suspected PRS patient [2]. * **Leptospirosis Marker:** Look for a history of exposure to contaminated water/rodents and "conjunctival suffusion" (red eyes without discharge). * **Paraquat:** Characterized by a "tongue corrosive" appearance and a high mortality rate; there is no specific antidote.

Question 262: What is the best therapy for hepato-renal syndrome?

A. Renal transplantation
B. Liver transplantation (Correct Answer)
C. Transjugular intrahepatic portosystemic shunt
D. Dialysis

Explanation: **Explanation:** **Hepatorenal Syndrome (HRS)** is a functional renal failure occurring in patients with advanced liver disease (cirrhosis or acute liver failure) characterized by intense renal vasoconstriction [1]. **1. Why Liver Transplantation is the Correct Answer:** The underlying pathophysiology of HRS is not a primary kidney disease, but rather extreme systemic vasodilation (splanchnic) leading to compensatory renal vasoconstriction [1]. Since the renal failure is a direct consequence of liver dysfunction, **Liver Transplantation** is the definitive and only curative treatment [1]. It reverses the hemodynamic changes and restores normal renal function in the majority of patients. **2. Analysis of Incorrect Options:** * **Renal Transplantation (A):** The kidneys in HRS are structurally normal [1]. If transplanted into a person with a healthy liver, these kidneys would function perfectly. Therefore, replacing the kidneys is unnecessary unless there is co-existing end-stage renal disease. * **TIPS (C):** While TIPS can improve renal function by reducing portal hypertension, it is often used as a "bridge" to transplant or in specific refractory cases. It is not the definitive "best" therapy. * **Dialysis (D):** Renal Replacement Therapy (RRT) is a supportive measure used to manage fluid overload, hyperkalemia, or metabolic acidosis. It does not treat the underlying cause and has no impact on long-term survival without a transplant [1]. **Clinical Pearls for NEET-PG:** * **Medical Management (Bridge to Transplant):** The preferred medical therapy is a combination of **Terlipressin** (vasoconstrictor) and **Albumin** (volume expansion) [1]. * **Diagnosis:** HRS is a diagnosis of exclusion. A key criterion is the failure of serum creatinine to improve after at least 2 days of diuretic withdrawal and volume expansion with albumin. * **Type 1 vs. Type 2:** Type 1 (now called HRS-AKI) is rapidly progressive; Type 2 (HRS-NAKI) is more chronic and associated with refractory ascites [1].

Question 263: In nephrotic syndrome, what is the essential feature?

A. Proteinuria (Correct Answer)
B. Hypoalbuminemia
C. Hyperlipemia
D. Edema

Explanation: Nephrotic syndrome is a clinical complex characterized by a triad of findings resulting from increased glomerular permeability. While all four options are components of the syndrome, **Proteinuria** is the essential, primary feature that initiates the entire pathophysiological cascade [1]. **1. Why Proteinuria is the Correct Answer:** The hallmark of nephrotic syndrome is **massive proteinuria (>3.5 g/24 hours)**. It occurs due to the loss of the glomerular filtration barrier's integrity (either charge-selective or size-selective) [1]. This massive loss of protein is the "sine qua non" of the condition; without nephrotic-range proteinuria, the subsequent clinical and biochemical features cannot develop [1]. **2. Why other options are incorrect:** * **Hypoalbuminemia (<3 g/dL):** This is a *consequence* of massive proteinuria. While nearly always present, it is secondary to the urinary loss of albumin and increased hepatic catabolism [1]. * **Hyperlipemia:** This is a *compensatory* response. The liver increases the synthesis of lipoproteins (VLDL, LDL) to maintain oncotic pressure in response to low albumin [1]. * **Edema:** This is the *clinical manifestation*. It occurs due to decreased plasma oncotic pressure (Starling forces) and secondary sodium/water retention [1]. It is the most common presenting symptom but not the defining physiological event. **High-Yield Clinical Pearls for NEET-PG:** * **Definition:** Nephrotic range proteinuria is >3.5 g/day in adults or >40 mg/m²/hr in children. * **Mnemonic (NAPH):** **N**ephrotic range proteinuria, **A**lbumins low, **P**uffiness (Edema), **H**yperlipidemia. * **Most Common Cause:** Minimal Change Disease (Children); Focal Segmental Glomerulosclerosis (Adults worldwide); Membranous Nephropathy (Older adults) [2]. * **Hypercoagulability:** Patients are at high risk for Renal Vein Thrombosis due to the loss of Antithrombin III in urine.

Question 264: A female patient presents with an upper respiratory tract infection. After 15 days, she develops hematuria. What is the probable diagnosis?

A. IgA nephropathy
B. Wegener's granulomatosis
C. Henoch-Schönlein purpura
D. Post-streptococcal glomerulonephritis (Correct Answer)

Explanation: ### Explanation The key to solving this question lies in the **latent period** between the infection and the onset of renal symptoms. **1. Why Post-Streptococcal Glomerulonephritis (PSGN) is correct:** PSGN is an immune-complex-mediated (Type III hypersensitivity) reaction that occurs after an infection with Group A Beta-hemolytic *Streptococcus* [1]. A crucial diagnostic feature is the **latent period of 1–3 weeks (average 10–14 days)** after a sore throat (pharyngitis) or 3–6 weeks after a skin infection (impetigo) [1]. During this time, the body forms immune complexes that eventually deposit in the glomerular basement membrane, leading to hematuria, edema, and hypertension [1]. **2. Why the other options are incorrect:** * **IgA Nephropathy:** This is the most common cause of "synpharyngitic" hematuria [2]. The hematuria occurs **concurrently** or within **1–2 days** of the respiratory infection [2]. The 15-day gap in this case makes PSGN much more likely. * **Wegener’s Granulomatosis (GPA):** While it involves the upper respiratory tract (sinusitis/otitis) and kidneys, it is a systemic vasculitis characterized by necrotizing granulomas and c-ANCA positivity, not typically triggered by a specific infection with a clear latent period. * **Henoch-Schönlein Purpura (HSP):** Although it can follow an URTI and presents with IgA deposition, it is characterized by a classic tetrad: palpable purpura (usually on lower limbs), arthralgia, abdominal pain, and renal involvement. **3. High-Yield Clinical Pearls for NEET-PG:** * **Low C3 Levels:** PSGN is characterized by transiently low Serum C3 levels, which typically normalize within 6–8 weeks. * **Microscopy:** Look for "Lumpy-Bumpy" deposits on Immunofluorescence and "Subepithelial Humps" on Electron Microscopy. * **ASO Titer:** Elevated in post-pharyngeal PSGN; Anti-DNase B is a better marker for post-impetigo PSGN. * **Prognosis:** Excellent in children; more likely to progress to chronic kidney disease in adults [1].

Question 265: A 40-year-old man is found to have severe metabolic acidosis with a high anion gap. What is the most likely cause?

A. Diarrhea
B. Methanol ingestion (Correct Answer)
C. Proximal renal tubular acidosis
D. Distal renal tubular acidosis

Explanation: ### Explanation **Correct Answer: B. Methanol ingestion** The primary diagnostic step in metabolic acidosis is calculating the **Anion Gap (AG)** using the formula: $Na^+ - (Cl^- + HCO_3^-)$. A normal AG is typically $12 \pm 2$ mEq/L. **Methanol ingestion** causes a **High Anion Gap Metabolic Acidosis (HAGMA)** [1]. When methanol is metabolized by alcohol dehydrogenase, it produces formic acid [2]. These unmeasured organic acid anions accumulate in the blood, replacing bicarbonate and increasing the anion gap [1], [2]. Other common causes of HAGMA are remembered by the mnemonic **MUDPILES** (Methanol, Uremia, DKA, Propylene glycol, Iron/INH, Lactic acidosis, Ethylene glycol, Salicylates). **Why the other options are incorrect:** * **Diarrhea (Option A):** This leads to a loss of bicarbonate-rich intestinal fluids. To maintain electroneutrality, the kidneys retain chloride, resulting in a **Normal Anion Gap Metabolic Acidosis (NAGMA)**, also known as hyperchloremic metabolic acidosis. * **Proximal RTA (Type 2) (Option C):** Caused by a defect in bicarbonate reabsorption in the proximal tubule. It results in NAGMA [4]. * **Distal RTA (Type 1) (Option D):** Caused by a failure of $H^+$ secretion in the distal tubule. It also results in NAGMA [4]. **High-Yield Clinical Pearls for NEET-PG:** 1. **Methanol Toxicity:** Classically presents with "snowfield vision" (optic papillitis) and can lead to permanent blindness or putaminal necrosis on MRI [2]. 2. **Osmolar Gap:** Methanol and Ethylene glycol are the two most common causes of HAGMA that also present with an **elevated Osmolar Gap** [1]. 3. **Treatment:** Fomepizole (inhibits alcohol dehydrogenase) is the preferred antidote; ethanol is an alternative [1]. Hemodialysis is indicated in severe cases [3].

Question 266: What is the most common neurological disturbance observed in patients with Chronic Kidney Disease (CKD)?

A. Seizures
B. Dementia (Correct Answer)
C. Peripheral neuropathy
D. Restless leg syndrome

Explanation: **Explanation:** The correct answer is **Dementia**. While CKD affects multiple systems, cognitive impairment and dementia are now recognized as the most frequent neurological complications, particularly in the elderly and those with end-stage renal disease (ESRD). **1. Why Dementia is Correct:** Cognitive decline in CKD is multifactorial, resulting from a combination of **chronic uremic encephalopathy**, microvascular disease (due to shared risk factors like hypertension and diabetes), and "silent" cerebral infarcts. Studies indicate that the prevalence of cognitive impairment in patients on dialysis can be as high as 30–70%, making it statistically the most common neurological disturbance in this population. **2. Why other options are incorrect:** * **Peripheral Neuropathy:** This is the most common **peripheral** nervous system manifestation (seen in ~60% of patients), but it is less prevalent than the broad spectrum of cognitive disturbances when considering the entire neurological system. * **Restless Leg Syndrome (RLS):** While highly characteristic of CKD (affecting 20–50% of dialysis patients), it is less common than cognitive decline [1]. It is usually idiopathic but can be associated with uraemia [1]. * **Seizures:** These are typically late-stage manifestations or acute complications of uremia, dialysis disequilibrium syndrome, or electrolyte imbalances, rather than the most common baseline disturbance. **Clinical Pearls for NEET-PG:** * **Uremic Encephalopathy:** Characterized by "asterixis" (flapping tremors), which is a classic high-yield physical finding. * **Dialysis Dementia:** A specific, rare progressive syndrome historically linked to **aluminum toxicity** from dialysate; however, general cognitive decline remains the most common overall finding today. * **Peripheral Neuropathy in CKD:** Typically presents as a symmetric, distal "stocking-glove" sensory-motor polyneuropathy. Improvement is often seen only after renal transplantation, not necessarily with dialysis alone.

Question 267: What is the diagnostic feature of chronic renal failure (CRF)?

A. Broad casts in urine (Correct Answer)
B. Elevated blood urea
C. Proteinuria
D. Bleeding diathesis

Explanation: **Explanation:** The hallmark diagnostic feature of **Chronic Renal Failure (CRF)**, now more commonly referred to as Chronic Kidney Disease (CKD), is the presence of **Broad Casts** in the urinary sediment. [1] **1. Why Broad Casts are the Correct Answer:** Broad casts (often called "Renal Failure Casts") are significantly wider than ordinary casts. They form in the **collecting ducts** that have undergone compensatory hypertrophy and dilation due to the loss of surrounding functioning nephrons. Their presence indicates severe, long-standing parenchymal damage and a significantly reduced number of functioning nephrons, making them highly specific for chronic renal disease. **2. Why other options are incorrect:** * **Elevated Blood Urea:** This is a feature of **Azotemia**, which can occur in Prerenal (dehydration), Renal (AKI/CKD), or Postrenal (obstruction) conditions. It is not specific to the chronicity of renal failure. * **Proteinuria:** While common in CKD (especially diabetic nephropathy), it is also a hallmark of **Acute Glomerulonephritis** and **Nephrotic Syndrome**. It does not differentiate between acute and chronic states. [2] * **Bleeding Diathesis:** This occurs in advanced uremia due to **platelet dysfunction** (impaired aggregation). While seen in CRF, it is a complication of the uremic state rather than a diagnostic feature of the renal failure itself. **High-Yield Clinical Pearls for NEET-PG:** * **Waxy Casts:** Often found alongside broad casts; they represent the end-stage of cast evolution and indicate extreme stasis in the nephron. * **Small Kidney Size:** On ultrasound (<9 cm), this is the most reliable sign of CRF, *except* in Diabetes, Amyloidosis, and Polycystic Kidney Disease (PKD), where kidneys may be normal or enlarged. * **Anemia in CRF:** Usually normocytic normochromic due to decreased Erythropoietin production.

Question 268: Which of the following is a sign of Acute Tubular Necrosis (ATN)?

A. Fractional Excretion of Sodium (FENa) <1
B. Renal Failure Index (RFI) <1
C. Blood Urea Nitrogen (BUN)/Creatinine ratio <20 (Correct Answer)
D. Urine osmolality >1.010

Explanation: **Explanation:** Acute Tubular Necrosis (ATN) is the most common cause of intrinsic acute kidney injury (AKI). It results from structural damage to the tubular epithelial cells, leading to a loss of the kidney's ability to concentrate urine and reabsorb electrolytes. **1. Why Option C is Correct:** In ATN, the damaged tubules cannot reabsorb urea effectively. In contrast to pre-renal azotemia (where urea is avidly reabsorbed along with water, leading to a ratio >20:1), the **BUN/Creatinine ratio in ATN remains low (<20:1)** because both urea and creatinine are excreted poorly at similar rates due to tubular dysfunction. **2. Why Incorrect Options are Wrong:** * **FENa <1% (Option A):** This is a hallmark of **Pre-renal AKI**, where intact tubules conserve sodium to restore volume. In ATN, tubular damage prevents sodium reabsorption, leading to a **FENa >2%**. * **RFI <1 (Option B):** Similar to FENa, a Renal Failure Index <1 indicates pre-renal states. In ATN, the **RFI is typically >2**. * **Urine Osmolality >1.010 (Option D):** This is a distractor. In ATN, the kidneys lose the ability to concentrate urine, resulting in **isosthenuria** (urine osmolality fixed at ~300 mOsm/kg, similar to plasma) and a low specific gravity (~1.010). A high urine osmolality (>500 mOsm/kg) is characteristic of pre-renal AKI. **Clinical Pearls for NEET-PG:** * **Microscopy:** Look for **"Muddy brown" granular casts**, which are pathognomonic for ATN. * **Urine Sodium:** Typically **>40 mEq/L** in ATN (vs. <20 mEq/L in pre-renal). * **Common Causes:** Ischemia (prolonged hypotension) or Nephrotoxins (Aminoglycosides, Contrast media, Myoglobinuria).

Question 269: A patient presents with hypotension in a confused state and metabolic alkalosis. Which of the following tests will best suggest the diagnosis?

A. Urine pH
B. Urine Na+ (Correct Answer)
C. Urine Cl-
D. Urine K+

Explanation: **Explanation:** The clinical presentation of **hypotension, confusion, and metabolic alkalosis** suggests a state of **volume depletion** (contraction alkalosis). In such cases, the body attempts to restore blood pressure by activating the Renin-Angiotensin-Aldosterone System (RAAS). **Why Urine Na+ is the Correct Answer:** In a patient with hypotension and metabolic alkalosis, the most critical diagnostic step is determining the volume status and the kidney's response to it. **Urine Sodium (UNa+)** is the most reliable marker for assessing effective arterial blood volume. * If **UNa+ < 20 mEq/L**, it indicates extra-renal volume loss (e.g., vomiting, nasogastric suction, or remote diuretic use) where the kidneys are avidly conserving sodium to correct hypotension. * If **UNa+ > 40 mEq/L**, it suggests renal causes of salt wasting (e.g., current diuretic use, Bartter’s, or Gitelman’s syndrome). **Analysis of Incorrect Options:** * **Urine Cl-:** While often used to classify metabolic alkalosis (chloride-responsive vs. resistant), in the specific context of **hypotension and confusion**, Urine Na+ is the primary indicator of the underlying hemodynamic instability and volume deficit. * **Urine pH:** This is unreliable because, in early metabolic alkalosis, the urine may be alkaline (bicarbonaturia), but in chronic states or severe volume depletion, "paradoxical aciduria" occurs [1]. * **Urine K+:** Potassium excretion is usually increased in metabolic alkalosis due to aldosterone action [1], but it does not help differentiate the etiology or volume status as effectively as sodium. **NEET-PG High-Yield Pearls:** * **Contraction Alkalosis:** Loss of chloride-rich, bicarbonate-poor fluid (e.g., vomiting) leads to volume depletion and alkalosis [1]. * **Paradoxical Aciduria:** In severe volume depletion, the kidney prioritizes Na+ reabsorption over H+ excretion, leading to acidic urine despite systemic alkalosis [1]. * **Diagnostic Rule:** For any patient with metabolic alkalosis and hypotension, always check **Urine Na+ and Cl-** to distinguish between GI losses and renal tubular pathologies.

Question 270: A patient presenting with hemoptysis and renal failure with anti-basement membrane antibodies has which of the following conditions?

A. Goodpasture syndrome (Correct Answer)
B. Wegener's granulomatosis
C. Churg-Strauss syndrome
D. Henoch-Schonlein purpura

Explanation: ### Explanation **Correct Option: A. Goodpasture syndrome** Goodpasture syndrome is characterized by the triad of **diffuse alveolar hemorrhage (hemoptysis)**, **glomerulonephritis (renal failure)**, and the presence of **anti-glomerular basement membrane (anti-GBM) antibodies** [1]. The underlying pathophysiology involves a Type II hypersensitivity reaction where antibodies are directed against the **alpha-3 chain of Type IV collagen**. This collagen is found in both the glomerular basement membrane and the pulmonary alveolar basement membrane, explaining the concurrent lung and kidney involvement. **Incorrect Options:** * **B. Wegener’s granulomatosis (GPA):** While it also presents with hemoptysis and renal failure (pulmonary-renal syndrome), it is associated with **c-ANCA (anti-PR3)** antibodies and granulomatous inflammation, not anti-GBM antibodies [2]. * **C. Churg-Strauss syndrome (EGPA):** This is a small-vessel vasculitis characterized by **asthma, eosinophilia, and p-ANCA**. While it can affect kidneys, the hallmark is allergic rhinitis and peripheral eosinophilia. * **D. Henoch-Schonlein purpura (IgA Vasculitis):** This typically presents with a tetrad of **palpable purpura, arthralgia, abdominal pain, and renal disease (IgA nephropathy)** [3]. It is mediated by IgA immune complex deposition, not anti-GBM antibodies. **High-Yield Clinical Pearls for NEET-PG:** * **Diagnosis:** Linear immunofluorescence (IF) on renal biopsy showing **linear IgG deposits** is pathognomonic for Goodpasture syndrome. * **Demographics:** Typically shows a bimodal age distribution (young men in their 20s and older women in their 60s). * **Treatment:** The mainstay of treatment is **plasmapheresis** (to remove circulating antibodies) combined with corticosteroids and cyclophosphamide [1]. * **Key Distinction:** If only the kidneys are involved (no hemoptysis), the condition is simply called **Anti-GBM disease** [1]. When pulmonary hemorrhage is present, it is **Goodpasture syndrome** [2].

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Acute Kidney Injury

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Chronic Kidney Disease

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Glomerular Diseases

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Tubulointerstitial Diseases

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Nephrotic and Nephritic Syndromes

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Urinary Tract Infections

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Renal Replacement Therapy

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Fluid and Electrolyte Disorders

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Acid-Base Disorders

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Kidney in Systemic Diseases

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Kidney Stones and Obstructive Uropathy

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Hypertension in Kidney Disease

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Nephrology — MCQs

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