Nephrology — MCQs

Nephrology Indian Medical PG Practice Questions and MCQs

Question 131: Proximal tubular dysfunction is seen in all of the following disorders EXCEPT?

A. Pompe disease
B. Lowe syndrome
C. Cystinosis
D. Fabry disease (Correct Answer)

Explanation: The question tests the ability to distinguish between various lysosomal storage disorders and their specific renal manifestations. Proximal tubular dysfunction, often manifesting as **Fanconi Syndrome** (characterized by glucosuria, phosphaturia, aminoaciduria, and bicarbonate loss), is a hallmark of certain metabolic diseases but is notably absent in others [1]. **1. Why Fabry Disease is the Correct Answer:** Fabry disease is an X-linked recessive deficiency of **$\alpha$-galactosidase A**, leading to the accumulation of globotriaosylceramide (Gb3). While it causes significant renal pathology, the primary site of damage is the **glomerulus** (podocytes) and the **distal nephron/collecting ducts**. It presents with proteinuria and progressive renal failure, but it does **not** typically cause proximal tubular dysfunction or Fanconi syndrome. **2. Analysis of Incorrect Options:** * **Cystinosis:** This is the **most common cause** of inherited Fanconi syndrome in children. Cystine crystals accumulate within the lysosomes of proximal tubular cells, leading to severe dysfunction. * **Lowe Syndrome (Oculocerebrorenal syndrome):** An X-linked disorder affecting the *OCRL1* gene. It presents with a classic triad of congenital cataracts, intellectual disability, and **proximal renal tubular acidosis**. * **Pompe Disease (GSD Type II):** While primarily a neuromuscular disorder (acid maltase deficiency), glycogen accumulation can occur in the proximal tubules, leading to tubular dysfunction in some clinical presentations. **Clinical Pearls for NEET-PG:** * **Fanconi Syndrome Mnemonic:** "**L**ow **C**ystine **W**ilson **G**lycogen" (**L**owe, **C**ystinosis, **W**ilson disease, **G**alactosemia/Glycogen storage diseases) [2]. * **Fabry Disease Key Finding:** Look for "Maltese cross" appearance of lipid droplets in urine and angiokeratomas on physical exam. * **Cystinosis Key Finding:** Corneal cystine crystals on slit-lamp exam.

Question 132: All are true for nephrotic syndrome except?

A. Edema
B. Massive proteinuria
C. Hyperlipidemia
D. Hypertension (Correct Answer)

Explanation: **Explanation:** Nephrotic syndrome is a clinical triad defined by a specific set of findings resulting from increased glomerular permeability to plasma proteins. **Why Hypertension is the Correct Answer (The "Except"):** Hypertension is a classic feature of **Nephritic Syndrome**, not Nephrotic Syndrome [1]. In Nephrotic Syndrome, the primary pathology is the loss of the glomerular filtration barrier's integrity, leading to massive protein loss [3]. While some patients with specific causes of nephrotic syndrome (like Focal Segmental Glomerulosclerosis) may develop hypertension over time due to renal scarring [1], it is **not** a defining diagnostic criterion. In fact, many nephrotic patients are initially normotensive or even hypotensive due to intravascular volume depletion. **Analysis of Incorrect Options:** * **Massive Proteinuria (Option B):** This is the hallmark of the condition [1]. It is defined as protein excretion **>3.5 g/24 hours** (or a protein:creatinine ratio >3000 mg/g). * **Edema (Option A):** This occurs due to decreased plasma oncotic pressure (Hypoalbuminemia <3 g/dL) and compensatory sodium/water retention by the kidneys [2]. It typically presents as soft, pitting, periorbital, or pedal edema. * **Hyperlipidemia (Option C):** Low plasma oncotic pressure stimulates the liver to increase the synthesis of lipoproteins (VLDL, LDL). Additionally, there is decreased clearance of lipids due to reduced lipoprotein lipase activity. **NEET-PG High-Yield Pearls:** * **The Nephrotic Pentad:** 1. Massive Proteinuria, 2. Hypoalbuminemia, 3. Generalized Edema, 4. Hyperlipidemia, 5. Lipiduria ("Maltese cross" appearance under polarized light). * **Hypercoagulability:** Patients are at high risk for venous thromboembolism (especially **Renal Vein Thosis**) due to the urinary loss of Antithrombin III and Protein C/S. * **Infection Risk:** Increased susceptibility to encapsulated organisms (e.g., *S. pneumoniae*) due to loss of IgG and complement factors in urine.

Question 133: A 30-year-old female patient is undergoing hemodialysis with an internal arteriovenous fistula in place. What measures should be taken to prevent complications associated with this device?

A. Insert intravenous lines above the fistula.
B. Avoid taking blood pressures in the arm with the fistula. (Correct Answer)
C. Palpate pulses above the fistula.
D. Report any bruit or thrill over the fistula to the physician.

Explanation: ### Explanation **Correct Option: B (Avoid taking blood pressures in the arm with the fistula)** The primary goal in managing an arteriovenous (AV) fistula is to maintain its **patency** and prevent thrombosis or stenosis. Haemodialysis specifically involves gaining access to the circulation through an arteriovenous fistula [1]. Applying a blood pressure cuff to the fistula arm causes temporary venous occlusion and high external pressure. This can lead to **stasis of blood flow**, increasing the risk of clot formation (thrombosis) and subsequent failure of the access site. Similarly, tight clothing or sleeping on the affected arm should be avoided. **Analysis of Incorrect Options:** * **Option A:** Intravenous (IV) lines or venipunctures should **never** be performed on the fistula arm. This prevents the risk of infection (phlebitis), hematoma formation, and damage to the vessel wall, which could compromise future dialysis sessions. * **Option C:** While distal pulses are monitored, the most critical assessment for a fistula is the presence of a **thrill** (palpable vibration) and **bruit** (audible whooshing), which signify turbulent flow and patency. * **Option D:** A bruit and thrill are **normal and expected** findings in a functioning AV fistula. Their *absence* or a change in their intensity is what should be reported immediately, as it indicates potential occlusion. **Clinical Pearls for NEET-PG:** * **Gold Standard:** The AV fistula (typically Radiocephalic or Brachiocephalic) is the preferred long-term vascular access due to lower infection rates and higher longevity compared to grafts or catheters. * **Maturation:** A new fistula usually requires **6–8 weeks** to "mature" (vein arterialization) before it can be used for dialysis. * **Steal Syndrome:** A known complication where distal ischemia occurs because the fistula "steals" blood from the hand; look for coldness, pain, or pallor in the fingers. * **Rule of 6s:** A mature fistula should have a flow >600 mL/min, be <6 mm deep, and have a diameter >6 mm.

Question 134: A 22-year-old male presents with fever, hematuria, and hypertension. Intravenous pyelography (IVP) shows a "spider leg" deformity. What is the most likely diagnosis?

A. Autosomal dominant polycystic kidney disease (ADPKD) (Correct Answer)
B. Autosomal recessive polycystic kidney disease (ARPKD)
C. Medullary sponge kidney
D. Hydronephrosis

Explanation: ### Explanation **Correct Option: A. Autosomal dominant polycystic kidney disease (ADPKD)** The "spider leg" appearance on Intravenous Pyelography (IVP) is a classic radiological sign of ADPKD. This occurs because multiple large, fluid-filled cysts in the renal parenchyma compress and stretch the renal calyces and pelvis, making them appear elongated, thin, and spindly—resembling the legs of a spider. Clinically, ADPKD often presents in young adults (20–40 years) [1] with a triad of hypertension, hematuria, and palpable abdominal masses (flank pain). **Analysis of Incorrect Options:** * **B. ARPKD:** Typically presents in infancy or childhood with bilateral flank masses and renal failure. On IVP, it shows a characteristic **"sunray" or "paintbrush" appearance** due to dilated collecting ducts, rather than calyceal stretching. * **C. Medullary sponge kidney:** Characterized by cystic dilatation of the collecting ducts. The classic IVP finding is a **"bouquet of flowers" or "paintbrush" appearance** [2] due to the accumulation of contrast in the dilated ducts. * **D. Hydronephrosis:** Results in the dilatation of the renal pelvis and calyces. On IVP, this appears as **"clubbing" of the calyces**, not the thin, elongated deformity seen in ADPKD. **High-Yield Clinical Pearls for NEET-PG:** * **Genetics:** Most common cause is a mutation in the **PKD1 gene** (Chromosome 16), followed by PKD2 (Chromosome 4) [1]. * **Extra-renal manifestations:** The most common is **Liver cysts**. The most serious is **Berry aneurysms** (leading to Subarachnoid Hemorrhage). Others include mitral valve prolapse and diverticulosis. * **Diagnosis:** Ultrasound is the initial investigation of choice (Revised Ravine’s criteria). * **Treatment:** Tolvaptan (Vasopressin V2 receptor antagonist) is used to slow disease progression.

Question 135: How is glomerular proteinuria differentiated from non-glomerular proteinuria?

A. Proteinuria > 3.0 - 3.5 g/day (Correct Answer)
B. Globulin > albumin
C. Albumin to B2 microglobulin ratio 100:1
D. Tamm-Horsfall protein

Explanation: The differentiation between glomerular and non-glomerular (tubular or overflow) proteinuria is based on the **quantity** and **composition** of the proteins excreted. **1. Why Option A is Correct:** The glomerular filtration barrier (basement membrane and podocytes) normally restricts large proteins like albumin [2]. When this barrier is significantly damaged (e.g., Nephrotic Syndrome), massive amounts of protein leak into the urine [1]. **Proteinuria > 3.0 - 3.5 g/day** is almost exclusively a hallmark of **glomerular disease** [1]. In contrast, tubular or overflow proteinuria rarely exceeds 2 g/day because the filtered load of small proteins is limited. **2. Analysis of Incorrect Options:** * **Option B:** In glomerular proteinuria, **Albumin > Globulin** (selective or non-selective). Globulins predominate in "Overflow Proteinuria" (e.g., Multiple Myeloma) [1]. * **Option C:** The **Albumin to $eta_2$-microglobulin ratio** is a classic differentiator. In glomerular disease, the ratio is high (**>1000:1**) because albumin is the primary protein. A ratio of **<10:1** suggests tubular disease, where low-molecular-weight proteins like $eta_2$-microglobulin are not reabsorbed. * **Option D:** **Tamm-Horsfall protein** (Uromodulin) is a physiological protein secreted by the thick ascending limb of Henle. It is the matrix for all urinary casts but does not help differentiate the etiology of pathological proteinuria. **Clinical Pearls for NEET-PG:** * **Gold Standard for quantification:** 24-hour urine protein collection (though Spot Protein-Creatinine Ratio is preferred in practice) [1]. * **Dipstick Sensitivity:** Primarily detects **Albumin** [1]. It may miss Bence-Jones proteins (globulins) seen in Multiple Myeloma (Sulfosalicylic acid test is used instead) [1]. * **Microalbuminuria:** 30–300 mg/day; the earliest sign of Diabetic Nephropathy [1].

Question 136: Chronic renal failure with inappropriately high haemoglobin levels may be seen with which of the following conditions?

A. Hypertensive nephropathy
B. Ischaemic nephropathy
C. Diabetic nephropathy
D. Polycystic renal disease (Correct Answer)

Explanation: **Explanation:** In most cases of Chronic Kidney Disease (CKD), patients develop **normocytic normochromic anemia** due to the deficiency of Erythropoietin (EPO), which is primarily produced by the peritubular interstitial cells of the kidney [4]. **Why Polycystic Kidney Disease (PKD) is the correct answer:** In **Autosomal Dominant Polycystic Kidney Disease (ADPKD)**, the renal cysts are lined with epithelial cells that can become hypoxic due to the expansion of the cysts compressing surrounding vasculature. This localized intrarenal hypoxia stimulates the cyst walls and the remaining compressed parenchyma [1] to continue producing **Erythropoietin**. Consequently, patients with PKD often maintain higher hemoglobin levels than expected for their degree of renal failure, and in some cases, they may even develop secondary polycythemia. **Why the other options are incorrect:** * **A & B (Hypertensive and Ischaemic Nephropathy):** These conditions involve progressive loss of the renal parenchyma and interstitial fibrosis [3], leading to a predictable decline in EPO production and significant anemia. * **C (Diabetic Nephropathy):** This is actually associated with **disproportionately severe anemia** [2]. Damage to the autonomic nerves (denervation of the kidney) and tubulointerstitial fibrosis often lead to an earlier and more profound EPO deficiency compared to other causes of CKD. **High-Yield Clinical Pearls for NEET-PG:** * **"Relative Polycythemia" in CKD:** Apart from ADPKD, other renal conditions associated with high EPO/Hgb include **Renal Cell Carcinoma (RCC)**, Hydronephrosis, and Post-renal transplant erythrocytosis. * **Anemia in CKD:** Usually starts when GFR falls below **30-45 mL/min**. * **Target Hgb:** In CKD patients on EPO therapy, the target Hgb is typically **10–11.5 g/dL**; exceeding 13 g/dL increases the risk of cardiovascular events and stroke.

Question 137: Which of the following are considered bad prognostic factors in Lupus Nephritis?

A. Anti-ds DNA antibodies
B. Hypocomplementemia
C. Persistent proteinuria (>3 gm/day)
D. All of the above (Correct Answer)

Explanation: Lupus Nephritis (LN) is one of the most severe complications of Systemic Lupus Erythematosus (SLE). [1] Prognosis is determined by both clinical markers and histological findings (ISN/RPS classification). **Why "All of the Above" is Correct:** The progression of renal damage in SLE is driven by immune complex deposition and subsequent inflammatory cascades. The following are established indicators of poor renal outcomes: * **Anti-dsDNA Antibodies:** High titers are strongly associated with active lupus nephritis (especially Class III and IV). They correlate with disease flares and indicate a higher risk of progression to End-Stage Renal Disease (ESRD). * **Hypocomplementemia (Low C3, C4):** Low complement levels signify active classical pathway consumption due to immune complex formation. Persistent hypocomplementemia despite treatment suggests ongoing disease activity and a higher likelihood of chronic scarring. * **Persistent Proteinuria (>3 gm/day):** Nephrotic-range proteinuria that fails to resolve with induction therapy is a major predictor of poor long-term prognosis. It indicates significant glomerular basement membrane damage and increases the risk of interstitial fibrosis. **Clinical Pearls for NEET-PG:** 1. **Most Common Cause of Death in SLE:** Renal failure (early) and Cardiovascular disease (late). 2. **Gold Standard for Diagnosis:** Renal Biopsy. It is essential to differentiate between proliferative (Class III/IV) and membranous (Class V) types, as management differs. [1] 3. **Most Common & Severe Type:** Class IV (Diffuse Proliferative Lupus Nephritis). 4. **Other Bad Prognostic Factors:** Elevated Serum Creatinine at presentation, African-American ethnicity, and high "Chronicity Index" on biopsy. 5. **Treatment Goal:** Achieving a "Complete Renal Response" (proteinuria <0.5g/day and normal Cr) within 6–12 months is the best predictor of long-term kidney survival.

Question 138: Which of the following is not a common manifestation of nephrotic syndrome?

A. Hyperlipidemia
B. Hematuria (Correct Answer)
C. Anasarca
D. Hypoalbuminemia

Explanation: **Explanation:** The hallmark of **Nephrotic Syndrome** is the disruption of the glomerular filtration barrier (specifically the podocytes), leading to massive protein loss [1]. To diagnose Nephrotic Syndrome, a triad of clinical findings must be present: **Heavy proteinuria (>3.5 g/day), Hypoalbuminemia (<3 g/dL), and Generalized Edema (Anasarca).** **Why Hematuria is the correct answer:** Hematuria is the classic feature of **Nephritic Syndrome**, which involves inflammatory damage to the glomerular capillaries (e.g., PSGN, IgA Nephropathy) [1]. While "microscopic" hematuria can occasionally occur in certain nephrotic conditions (like Membranous Nephropathy), it is **not** a defining or common manifestation. Nephrotic syndrome is primarily a "non-inflammatory" protein-losing state. **Analysis of Incorrect Options:** * **Hypoalbuminemia:** Direct result of massive urinary protein loss (proteinuria) [1]. As the liver cannot synthesize albumin fast enough to compensate for the loss, serum levels drop. * **Anasarca:** Low serum albumin decreases **plasma oncotic pressure**, leading to fluid extravasation into the interstitium, causing generalized edema (anasarca) [1]. * **Hyperlipidemia:** In response to low oncotic pressure, the liver increases the synthesis of lipoproteins (LDL, VLDL) [1]. Additionally, there is decreased catabolism of lipids due to the loss of lipoprotein lipase in the urine. **High-Yield Clinical Pearls for NEET-PG:** * **Hypercoagulability:** Nephrotic patients are at high risk for venous thromboembolism (especially **Renal Vein Thrombosis**) due to the urinary loss of **Antithrombin III**, Protein C, and S [1]. * **Infection Risk:** Increased susceptibility to encapsulated organisms (e.g., *S. pneumoniae*) due to the loss of **Immunoglobulins** and Complement factors in urine [1]. * **Maltese Cross Appearance:** Seen under polarized microscopy in the urine sediment due to lipiduria (fatty casts).

Question 139: Chronic laxative abuse can result in the formation of which type of renal stone?

A. Xanthine
B. Cysteine
C. Ammonium urate (Correct Answer)
D. Struvite

Explanation: **Explanation:** The correct answer is **Ammonium urate**. **Pathophysiology:** Chronic laxative abuse leads to chronic diarrhea, resulting in significant loss of water, bicarbonate, and potassium from the gastrointestinal tract. This triggers a specific metabolic environment conducive to ammonium urate stone formation: 1. **Dehydration:** Leads to low urine volume and concentrated urine. 2. **Metabolic Acidosis:** Loss of bicarbonate causes the kidneys to increase **ammoniagenesis** (production of $NH_4^+$) to buffer the acid. 3. **Hypokalemia:** Intracellular potassium depletion further stimulates renal ammonia production. 4. **Hyperuricosuria:** The resulting acidic, concentrated urine with high ammonium concentrations promotes the precipitation of ammonium acid urate. **Analysis of Incorrect Options:** * **A. Xanthine:** These are rare stones typically associated with hereditary xanthine oxidase deficiency or the use of Allopurinol. * **B. Cysteine:** These occur due to an autosomal recessive defect in the transport of dibasic amino acids (COLA: Cysteine, Ornithine, Lysine, Arginine) in the proximal tubule. * **D. Struvite (Triple Phosphate):** These are "infection stones" (Magnesium Ammonium Phosphate) associated with urease-producing bacteria like *Proteus* or *Klebsiella*, which make the urine alkaline [1]. **Clinical Pearls for NEET-PG:** * **Ammonium urate stones** are radiolucent (like pure uric acid stones) but may appear faintly radiopaque if they co-precipitate with calcium [2]. * They are also commonly seen in patients with **inflammatory bowel disease (IBD)** due to similar chronic malabsorption/diarrhea mechanisms. * **Key Triad for Laxative Abuse:** Hypokalemia, metabolic alkalosis (if vomiting) or acidosis (if diarrhea), and ammonium urate stones.

Question 140: A patient has Insulin-Dependent Diabetes Mellitus diagnosed at age 15 years. What is the most reliable indicator for diabetic nephropathy?

A. Urine albumin less than 50 mg per day in 3 consecutive samples
B. Urinary protein greater than 550 mg per day for 3 consecutive samples (Correct Answer)
C. Development of diabetic retinopathy
D. Hematuria

Explanation: **Explanation:** Diabetic Nephropathy (DN) is a clinical syndrome characterized by persistent albuminuria, a decline in GFR, and elevated blood pressure. The diagnosis is traditionally staged based on the level of protein excretion [1], [5]. **Why Option B is Correct:** The hallmark of established (overt) diabetic nephropathy is **persistent proteinuria** [2]. In clinical practice and for examination purposes, "persistent" is defined as positive results on at least two to three occasions over 3–6 months. While the threshold for macroalbuminuria is technically >300 mg/day, the presence of **urinary protein >550 mg/day** (which falls well into the range of overt nephropathy) across three consecutive samples is a definitive and reliable indicator of established renal structural damage in a diabetic patient. **Why Other Options are Incorrect:** * **Option A:** Urine albumin <50 mg/day is within the normal to high-normal range (Normal is <30 mg/day). This does not indicate nephropathy [1]. * **Option C:** While diabetic retinopathy is highly correlated with nephropathy (especially in Type 1 DM), it is a marker of microvascular damage in the eye, not a direct indicator of renal status [4]. * **Option D:** Hematuria is not a typical feature of diabetic nephropathy. Its presence should prompt an investigation for alternative diagnoses like glomerulonephritis or urological malignancy [3], [5]. **NEET-PG High-Yield Pearls:** * **Earliest Sign:** The earliest clinical sign of DN is **Microalbuminuria** (30–300 mg/day) [1], [2]. * **First Pathological Change:** Thickening of the glomerular basement membrane (GBM) [2]. * **Most Specific Pathological Change:** **Kimmelstiel-Wilson (KW) nodules** (nodular glomerulosclerosis) [2]. * **Screening:** In Type 1 DM, start screening 5 years after diagnosis. In Type 2 DM, start screening at the time of diagnosis [2]. * **Natural History:** DN usually takes 10–15 years to develop after the onset of Type 1 DM [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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