Nephrology — MCQs

Nephrology Indian Medical PG Practice Questions and MCQs

Question 341: Renal replacement therapy replaces all functions of the kidney except which of the following?

A. Endocrine function (Correct Answer)
B. Urine output
C. Blood biochemistry
D. Ultrafiltration

Explanation: ### Explanation The kidney is a complex organ with two primary roles: **Excretory** (removing waste and excess fluid) and **Endocrine/Metabolic** (hormone production and vitamin activation). **Why "Endocrine function" is the correct answer:** Renal Replacement Therapy (RRT), such as hemodialysis or peritoneal dialysis, utilizes physical processes like **diffusion** and **convection** across a semi-permeable membrane [1]. While these processes effectively clear toxins and balance electrolytes, they cannot replicate the biological synthesis of hormones. Specifically, RRT cannot produce **Erythropoietin** (required for RBC production) or perform the **1-alpha-hydroxylation of Vitamin D** (required for calcium homeostasis) [2]. Consequently, patients on dialysis still require exogenous supplementation of erythropoietin and calcitriol [2]. **Analysis of incorrect options:** * **B. Urine output:** While dialysis doesn't always restore natural micturition, it replaces the *function* of fluid removal, effectively managing the body's volume status [1]. * **C. Blood biochemistry:** RRT corrects azotemia (high urea/creatinine) and manages life-threatening electrolyte imbalances (like hyperkalemia) and acid-base disturbances (metabolic acidosis). * **D. Ultrafiltration:** This is a core component of RRT where hydrostatic pressure is used to remove excess plasma water, replacing the kidney's ability to prevent fluid overload [1], [3]. **High-Yield Clinical Pearls for NEET-PG:** * **The "Big Three" Endocrine Functions:** Remember **Erythropoietin** (stimulates bone marrow), **Renin** (blood pressure regulation), and **Calcitriol** (active Vitamin D). * **Dialysis Disequilibrium Syndrome:** A common high-yield complication caused by the rapid removal of urea, leading to cerebral edema. * **Indications for Urgent Dialysis (AEIOU):** **A**cidosis, **E**lectrolytes (Hyperkalemia), **I**ngestion (Toxins), **O**verload (Fluid), **U**remia (Pericarditis/Encephalopathy).

Question 342: High anion gap acidosis is seen in all of the following conditions, EXCEPT:

A. Diabetic Ketoacidosis
B. Lactic Acidosis
C. Renal Tubular Acidosis (Correct Answer)
D. Methanol Poisoning

Explanation: Metabolic acidosis is categorized based on the **Anion Gap (AG)**, calculated as $[Na^+] - ([Cl^-] + [HCO_3^-])$. The normal range is 8–12 mEq/L. ### **Explanation of the Correct Answer** **C. Renal Tubular Acidosis (RTA):** This is the correct answer because RTA is a classic cause of **Normal Anion Gap Metabolic Acidosis (NAGMA)**, also known as hyperchloremic metabolic acidosis [1]. In RTA, there is either a failure to reabsorb bicarbonate (Type 2) or a failure to excrete hydrogen ions (Type 1/4). To maintain electroneutrality as bicarbonate is lost, the kidneys retain Chloride ($Cl^-$). Since the increase in chloride offsets the decrease in bicarbonate, the anion gap remains within the normal range [1]. ### **Analysis of Incorrect Options (Causes of HAGMA)** In **High Anion Gap Metabolic Acidosis (HAGMA)**, an unmeasured acid anion (not chloride) accumulates, replacing bicarbonate. * **A. Diabetic Ketoacidosis:** Accumulation of acetoacetate and beta-hydroxybutyrate [2]. * **B. Lactic Acidosis:** Accumulation of lactate due to tissue hypoxia or sepsis [1]. * **D. Methanol Poisoning:** Metabolism of methanol into formic acid [3]. ### **NEET-PG High-Yield Pearls** * **Mnemonic for HAGMA (MUDPILES):** **M**ethanol, **U**remia, **D**KA, **P**araldehyde/Propylene glycol, **I**soniazid/Iron, **L**actic acidosis, **E**thylene glycol, **S**alicylates [1]. * **Mnemonic for NAGMA (USED CARP):** **U**reterosigmoidostomy, **S**aline infusion, **E**ndocrine (Addison’s), **D**iarrhea, **C**arbonic anhydrase inhibitors, **A**mmonium chloride, **R**enal Tubular Acidosis, **P**ancreatic fistula. * **Golden Rule:** If the question mentions "Hyperchloremia" along with acidosis, always look for RTA or Diarrhea as the answer [1].

Question 343: A patient presents with hemoptysis and hematuria a few weeks after a respiratory tract infection. ANCA antibodies are present. What is the likely diagnosis?

A. Goodpasture's syndrome (Correct Answer)
B. IgA Nephropathy
C. Nephrotic syndrome
D. Post-streptococcal glomerulonephritis (PSGN)

Explanation: ### Explanation **Correct Answer: A. Goodpasture's Syndrome** Goodpasture’s syndrome (Anti-GBM disease) is characterized by the clinical triad of **diffuse alveolar hemorrhage (hemoptysis)** and **glomerulonephritis (hematuria)** [3]. It is caused by Type II hypersensitivity, where antibodies are directed against the **alpha-3 chain of Type IV collagen** found in the glomerular and alveolar basement membranes. While the question mentions ANCA, it is a high-yield fact that up to **30-50% of patients with Anti-GBM disease are "double-positive"** (positive for both Anti-GBM and ANCA, usually p-ANCA). The combination of pulmonary and renal symptoms (Pulmonary-Renal Syndrome) following a viral trigger is classic for this diagnosis [5]. **Why Incorrect Options are Wrong:** * **B. IgA Nephropathy:** This is the most common cause of glomerulonephritis worldwide. It presents as "synpharyngitic" hematuria (occurring *during* an infection), but it typically lacks the massive pulmonary hemorrhage seen in this case [1]. * **C. Nephrotic Syndrome:** This presents with heavy proteinuria (>3.5g/day), edema, and hypoalbuminemia. It does not typically present with hemoptysis or acute nephritic features like gross hematuria [2]. * **D. Post-streptococcal glomerulonephritis (PSGN):** This occurs 1–3 weeks after a skin or throat infection [2]. While it causes hematuria, it does not involve the lungs (hemoptysis) and is associated with low C3 levels, not ANCA or Anti-GBM antibodies. **NEET-PG High-Yield Pearls:** * **Immunofluorescence (IF):** Goodpasture’s shows **Linear IgG deposits** along the GBM [4]. (Contrast this with PSGN, which shows "lumpy-bumpy" granular deposits). * **Pulmonary-Renal Syndromes:** Always consider Goodpasture’s, GPA (Wegener’s), and Microscopic Polyangiitis (MPA) when both organs are involved [3]. * **Treatment:** The mainstay of treatment is **Plasmapheresis** (to remove circulating antibodies) combined with corticosteroids and cyclophosphamide [3].

Question 344: Plasmapheresis is the treatment of choice for which of the following conditions?

A. Henoch-Schönlein purpura
B. Wegener's granulomatosis
C. Goodpasture's syndrome (Correct Answer)
D. Acute renal transplant rejection

Explanation: **Explanation:** **Goodpasture’s Syndrome (Anti-GBM Disease)** is the correct answer because the pathogenesis involves circulating pathogenic autoantibodies directed against the alpha-3 chain of Type IV collagen in the glomerular basement membrane (GBM) and pulmonary alveoli [1]. **Plasmapheresis** is the treatment of choice because it directly and rapidly removes these circulating anti-GBM antibodies from the plasma, preventing further irreversible damage to the kidneys and lungs (pulmonary hemorrhage) [1]. It is typically combined with corticosteroids and cyclophosphamide to suppress further antibody production [1]. **Analysis of Incorrect Options:** * **Henoch-Schönlein purpura (HSP):** This is an IgA-mediated small-vessel vasculitis. Management is primarily supportive; steroids are used for severe abdominal or renal involvement, but plasmapheresis is not a standard first-line therapy. * **Wegener's granulomatosis (GPA):** While plasmapheresis may be used in severe cases of ANCA-associated vasculitis (especially if serum creatinine is >5.7 mg/dL), the primary treatment of choice is a combination of glucocorticoids and immunosuppressants (Cyclophosphamide or Rituximab) [3]. * **Acute renal transplant rejection:** The first-line treatment for acute cellular rejection is pulse methylprednisolone. Plasmapheresis is reserved specifically for *antibody-mediated* rejection (AMR), not all acute rejection episodes. **High-Yield Clinical Pearls for NEET-PG:** * **Indications for Plasmapheresis:** Goodpasture’s Syndrome, TTP (Treatment of choice), Guillain-Barré Syndrome, Myasthenia Gravis (crisis), and Hyperviscosity Syndrome. * **Goodpasture’s Triad:** Glomerulonephritis (Crescentic), Pulmonary hemorrhage (Hemoptysis), and Anti-GBM antibodies [1]. * **Immunofluorescence:** Shows a characteristic **linear** IgG deposition along the GBM, unlike the "lumpy-bumpy" granular pattern seen in most other glomerulonephritides [2].

Question 345: Which of the following findings is not included in the definition of nephrotic syndrome?

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

Explanation: Nephrotic syndrome is a clinical triad defined by a specific set of findings resulting from increased glomerular permeability to plasma proteins [1]. The diagnostic criteria include: 1. **Massive Proteinuria:** >3.5 g/24 hours (or a protein:creatinine ratio >3000 mg/g) [3]. 2. **Hypoalbuminemia:** Serum albumin <3.0 g/dL. 3. **Edema:** Often manifesting as **Anasarca** (generalized swelling) due to decreased oncotic pressure and sodium retention [4]. 4. **Hyperlipidemia and Lipiduria:** The liver increases lipoprotein synthesis in response to low oncotic pressure. **Why Microscopic Hematuria is the correct answer:** Microscopic hematuria is a hallmark of **Nephritic Syndrome** (inflammatory glomerular injury), not Nephrotic Syndrome [1]. While it can occasionally be seen in certain nephrotic conditions (like FSGS or Membranous Nephropathy), it is **not** part of the formal definition. **Analysis of Incorrect Options:** * **Anasarca (B):** This is a classic clinical feature of nephrotic syndrome caused by severe hypoalbuminemia leading to fluid shift into the interstitium [4]. * **Hyperlipidemia (C):** A defining metabolic derangement caused by compensatory hepatic synthesis of cholesterol and triglycerides. * **Hypoalbuminemia (D):** A core component of the definition, resulting directly from the massive urinary loss of albumin. **High-Yield Pearls for NEET-PG:** * **Most common cause of Nephrotic Syndrome in children:** Minimal Change Disease (MCD) [3]. * **Most common cause in adults:** Focal Segmental Glomerulosclerosis (FSGS) (globally) [2] or Membranous Nephropathy. * **Hypercoagulability:** Patients are at high risk for venous thromboembolism (especially Renal Vein Thrombosis) due to the loss of Antithrombin III in urine. * **Mnemonic for Nephrotic Range:** "PEAL" – **P**roteinuria, **E**dema, **A**lbumin (low), **L**ipids (high).

Question 346: Which of the following complications of chronic kidney disease does NOT improve after dialysis?

A. Pericarditis
B. Peripheral neuropathy
C. Myopathy (Correct Answer)
D. Seizures

Explanation: **Explanation:** In Chronic Kidney Disease (CKD), uremic toxins accumulate, leading to multi-system complications [1]. While dialysis effectively clears many small, water-soluble toxins, it does not reverse all uremic manifestations. **Why Myopathy is the correct answer:** Uremic myopathy is primarily driven by metabolic derangements that dialysis cannot fully correct, such as **Vitamin D deficiency, secondary hyperparathyroidism, and chronic inflammation.** [1] Furthermore, dialysis itself does not reverse the muscle atrophy or the underlying electrolyte imbalances at the cellular level effectively enough to restore muscle function. Therefore, myopathy often persists or even progresses despite adequate dialysis. **Analysis of Incorrect Options:** * **Pericarditis:** Uremic pericarditis is a classic **absolute indication** for starting dialysis. It typically responds rapidly to the removal of uremic toxins and fluid overload. * **Peripheral Neuropathy:** While severe, long-standing neuropathy may have limited recovery, early uremic neuropathy generally stabilizes or improves once dialysis is initiated and toxin levels are lowered [1]. * **Seizures:** Uremic encephalopathy, which manifests as confusion, asterixis, and seizures, is highly responsive to dialysis as the neurotoxic metabolites are cleared from the circulation [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Indications for Dialysis (AEIOU):** **A**cidosis (refractory), **E**lectrolytes (hyperkalemia), **I**ngestion (toxins), **O**verload (fluid), **U**remia (pericarditis, encephalopathy, neuropathy). * **Anemia of CKD:** Does NOT improve with dialysis; it requires Erythropoietin (EPO) replacement [1]. * **Renal Osteodystrophy:** Generally persists or worsens unless specific phosphate binders and Vitamin D analogs are used [1]. * **Platelet Dysfunction:** Uremic bleeding (due to platelet dysfunction) **improves** with dialysis, but acute management often requires Desmopressin (DDAVP).

Question 347: Type IA is associated with all of the following, except:

A. Urinary pH > 5.5
B. Normal Anion Gap Acidosis
C. Increased urinary calcium
D. Increased urinary citrate (Correct Answer)

Explanation: Type 1 Renal Tubular Acidosis (RTA), also known as **Distal RTA**, is characterized by a defect in the alpha-intercalated cells of the distal tubule, leading to an inability to secrete hydrogen ions ($H^+$). **Why Option D is the Correct Answer (The "Except"):** In Type 1 RTA, chronic metabolic acidosis leads to increased proximal tubular reabsorption of citrate from the filtrate to serve as a buffer. This results in **Hypocitraturia** (decreased urinary citrate). Since citrate is a potent inhibitor of calcium stone formation, its absence, combined with hypercalciuria, leads to the classic complication of **nephrocalcinosis** and calcium phosphate stones. Therefore, "Increased urinary citrate" is incorrect. **Analysis of Other Options:** * **Option A (Urinary pH > 5.5):** This is the hallmark of Type 1 RTA. Due to the failure of distal $H^+$ secretion, the urine cannot be acidified below a pH of 5.5, even in the presence of systemic acidemia [1]. * **Option B (Normal Anion Gap Acidosis):** All RTAs are characterized by a Hyperchloremic Normal Anion Gap Metabolic Acidosis (NAGMA), as the loss of bicarbonate (or failure to excrete acid) is compensated by an increase in serum chloride [1]. * **Option C (Increased urinary calcium):** Systemic acidosis causes bone buffering, which releases calcium and phosphate into the blood, leading to hypercalciuria. **High-Yield NEET-PG Pearls:** * **Hypokalemia:** Type 1 and Type 2 RTA typically present with low potassium, whereas Type 4 RTA presents with hyperkalemia. * **Associations:** Type 1 RTA is frequently associated with autoimmune conditions like **Sjögren’s syndrome**, Rheumatoid Arthritis, and use of Amphotericin B. * **Mnemonic:** "Type **1** is **D**istal" (1D) and involves **D**ones (Bones/Stones).

Question 348: What is the minimum number of Red Blood Cells per high-power field of urine required for the diagnosis of hematuria?

A. 3 RBC/hpf (Correct Answer)
B. 5 RBC/hpf
C. 8 RBC/hpf
D. 10 RBC/hpf

Explanation: ### Explanation **Correct Answer: A. 3 RBC/hpf** **Medical Concept:** Hematuria is defined as the presence of an abnormal number of red blood cells in the urine [1]. According to the **American Urological Association (AUA)** guidelines, clinically significant microscopic hematuria is defined as **≥3 red blood cells per high-power field (RBC/hpf)** in a properly collected urinary sediment from a single, microscopic evaluation. This threshold is chosen to balance sensitivity for detecting underlying pathology (such as malignancy or glomerulonephritis) while minimizing unnecessary invasive testing in healthy individuals. **Analysis of Incorrect Options:** * **B (5 RBC/hpf):** While some older literature used 5 RBC/hpf as a cutoff, current international guidelines have standardized the definition to ≥3 RBC/hpf to ensure early detection of urological cancers. * **C & D (8 and 10 RBC/hpf):** These values are significantly higher than the diagnostic threshold. Using these as a cutoff would result in a high rate of "false negatives," missing many patients with significant renal or bladder pathology. **High-Yield Clinical Pearls for NEET-PG:** * **Dipstick vs. Microscopy:** A urine dipstick is highly sensitive for heme but can yield **false positives** (due to myoglobinuria, hemoglobinuria, or povidone-iodine) [1]. Therefore, a positive dipstick **must** be confirmed with microscopic examination [1]. * **Dysmorphic RBCs:** The presence of acanthocytes or "mickey mouse" shaped cells suggests a **glomerular origin** (e.g., Glomerulonephritis). * **RBC Casts:** These are pathognomonic for glomerular disease or upper urinary tract bleeding. * **Pseudohematuria:** Red urine with a negative dipstick and no RBCs on microscopy can be caused by drugs (Rifampicin, Phenytoin) or foods (Beets, Blackberries) [1].

Question 349: All of the following decrease in Nephrotic syndrome except?

A. Fibrinogen (Correct Answer)
B. Thyroxin
C. Transferrin
D. Albumin

Explanation: In **Nephrotic Syndrome**, the fundamental pathology is increased glomerular permeability, leading to massive proteinuria (typically >3.5g/day). This results in the loss of various low-molecular-weight proteins in the urine [2]. **1. Why Fibrinogen is the correct answer:** Unlike most proteins, **Fibrinogen levels increase** in Nephrotic Syndrome. This occurs because the liver compensates for the low oncotic pressure (caused by hypoalbuminemia) by increasing the synthesis of proteins and lipids [2]. Fibrinogen is a large-molecular-weight protein that is not easily filtered by the damaged glomerulus. This increased synthesis, coupled with decreased fibrinolysis, contributes to the **hypercoagulable state** characteristic of the syndrome. **2. Why the other options are incorrect:** * **Albumin (D):** This is the primary protein lost in the urine due to its size and charge, leading to the hallmark hypoalbuminemia [1]. * **Thyroxin (B):** Thyroid-binding globulin (TBG) is lost in the urine. Consequently, total T4 levels decrease, although patients usually remain clinically euthyroid (Normal free T4). * **Transferrin (C):** This iron-transport protein is lost in the urine, which can lead to iron-deficiency anemia that is resistant to oral iron therapy. **Clinical Pearls for NEET-PG:** * **Hyperlipidemia:** Liver overproduction of lipoproteins (LDL, VLDL) leads to hypercholesterolemia and "fatty casts" (Maltese cross appearance) in urine. * **Infection Risk:** Loss of Immunoglobulin G (IgG) and Complement factors (Factor B) increases susceptibility to infections, especially *S. pneumoniae*. * **Hypercoagulability:** Loss of Antithrombin III, Protein C, and S, combined with increased Fibrinogen, leads to venous thrombosis (most commonly **Renal Vein Thrombosis**).

Question 350: Acute renal failure results in which of the following acid-base and electrolyte disturbances?

A. Hyperkalemic alkalosis
B. Hypokalemic alkalosis
C. Hyperkalemic acidosis (Correct Answer)
D. Hypokalemic acidosis

Explanation: In Acute Renal Failure (ARF), now commonly referred to as Acute Kidney Injury (AKI), the sudden decline in glomerular filtration rate (GFR) leads to the systemic accumulation of nitrogenous waste and metabolic byproducts [1]. ### **Why Hyperkalemic Acidosis is Correct:** 1. **Hyperkalemia:** The kidneys are the primary route for potassium excretion (90%). In ARF, the reduced filtration and impaired secretion of potassium in the distal tubule lead to its accumulation in the blood [2]. Additionally, the associated metabolic acidosis causes an extracellular shift of potassium (H+/K+ exchange). 2. **Metabolic Acidosis:** The kidneys fail to excrete "fixed" non-volatile acids (such as phosphates and sulfates) and show a reduced capacity to regenerate bicarbonate and excrete hydrogen ions [3]. This typically results in a **High Anion Gap Metabolic Acidosis (HAGMA)**. ### **Why Other Options are Incorrect:** * **Options A & B (Alkalosis):** ARF is characterized by the retention of acids, not their loss [4]. Alkalosis is rarely seen in renal failure unless there is concurrent massive vomiting or nasogastric suction [4]. * **Option D (Hypokalemic Acidosis):** While acidosis is present, potassium levels rise due to lack of renal clearance. Hypokalemia is more characteristic of Renal Tubular Acidosis (RTA) or diuretic use, not acute renal shutdown [5]. ### **NEET-PG High-Yield Pearls:** * **ECG in ARF:** Hyperkalemia is the most life-threatening electrolyte derangement in ARF. Look for **tall tented T-waves**, PR prolongation, and widened QRS complexes [2]. * **Anion Gap:** ARF typically causes a High Anion Gap Metabolic Acidosis due to the retention of unmeasured anions (phosphates, sulfates). * **Indications for Urgent Dialysis (AEIOU):** **A**cidosis (refractory), **E**lectrolytes (Hyperkalemia), **I**ngestion (toxins), **O**verload (fluid), **U**remia (encephalopathy/pericarditis).

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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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