Nephrology — MCQs

A 24-year-old woman has dipstick-positive results for blood in her urine, which have been repeated twice between menstrual periods and remain positive. Microscopic evaluation reveals RBCs, some of which are deformed and some are in the form of casts. Which of the following is the most likely cause of the hematuria?

Q548Medium

A plasma urea to creatinine ratio of 20:1 may be seen in which of the following conditions?

Q549Medium

Which of the following conditions is characterized by hyperchloremic acidosis with hypokalemia?

Q550Medium

A 47-year-old HIV-positive man presents with weakness. He has HIV nephropathy and adrenal insufficiency, and takes trimethoprim-sulfamethoxazole for PCP prophylaxis and triple-agent antiretroviral treatment. He was recently started on spironolactone for ascites due to alcoholic liver disease. Physical examination reveals normal vital signs, but his muscles are diffusely weak. Frequent extrasystoles are noted. He has mild ascites and 1+ peripheral edema. Laboratory studies show a serum creatinine of 2.5 mg/dL with a potassium value of 7.3 mEq/L. ECG shows peaking of the T-waves and QRS widening to 0.14 seconds. What is the most important immediate treatment for this patient's hyperkalemia?

Nephrology Indian Medical PG Practice Questions and MCQs

Question 541: What are the common manifestations of kidney disease?

A. Hypertension only
B. Neither renal edema nor hypertension
C. Renal edema only
D. Both renal edema and hypertension (Correct Answer)

Explanation: Kidney disease, whether acute (e.g., Acute Glomerulonephritis) or chronic (CKD), typically manifests through a combination of fluid overload and hemodynamic changes. The correct answer is **D** because both renal edema and hypertension are hallmark clinical features of renal dysfunction [3]. **1. Why the correct answer is right:** * **Renal Edema:** This occurs due to two primary mechanisms: **Salt and water retention** (due to decreased GFR) and **Hypoalbuminemia** (due to proteinuria, as seen in Nephrotic Syndrome [3]). Renal edema is characteristically "dependent" but often presents first as periorbital puffiness in the mornings. * **Hypertension:** The kidneys regulate blood pressure via the **Renin-Angiotensin-Aldosterone System (RAAS)** [2]. In kidney disease, ischemia or parenchymal damage triggers excessive renin release. Additionally, the inability to excrete sodium leads to volume expansion, further elevating blood pressure [3]. **2. Why incorrect options are wrong:** * **Options A & C:** These are incomplete. While a patient may present with only one symptom early on, both are considered classic cardinal manifestations. Ignoring one overlooks the systemic nature of renal failure. * **Option B:** This is factually incorrect as these are the two most common presenting signs in clinical practice [1]. **Clinical Pearls for NEET-PG:** * **Nephritic Syndrome:** Characterized by the triad of Hematuria, Hypertension, and Edema. * **Nephrotic Syndrome:** Characterized by massive Proteinuria (>3.5g/day), Hypoalbuminemia, and severe Edema (Anasarca) [3]. * **High-Yield Fact:** Hypertension is both a *cause* and a *consequence* of Chronic Kidney Disease [2]. Controlling BP (target <130/80 mmHg) is the most effective way to slow the progression of renal failure.

Question 542: All are indicated in a patient with cystinuria with multiple renal stones except?

A. Cysteamine (Correct Answer)
B. Increase fluid intake
C. Alkalinization of urine
D. Penicillamine

Explanation: **Explanation:** **Cystinuria** is an autosomal recessive disorder characterized by a defect in the COAL transporter (Cystine, Ornithine, Arginine, Lysine) in the proximal renal tubule. This leads to high urinary cystine levels, which are poorly soluble in acidic urine, resulting in recurrent hexagonal radiolucent stones. **Why Cysteamine is the correct answer (the "Except"):** Cysteamine is the treatment of choice for **Cystinosis** (a lysosomal storage disorder), not Cystinuria. In Cystinosis, cysteamine enters lysosomes and reacts with cystine to form a cysteine-cysteamine complex that can exit the lysosome. It has no role in preventing or dissolving renal stones in Cystinuria. **Analysis of other options:** * **Increase fluid intake:** This is the first-line management. Maintaining a high urine output (typically >3L/day) decreases the concentration of cystine below its solubility limit. * **Alkalinization of urine:** Cystine solubility increases significantly at a pH >7.5. Potassium citrate or sodium bicarbonate are used to maintain alkaline urine to prevent stone formation. * **Penicillamine:** This is a chelating agent used when conservative measures fail [1]. It reacts with cystine to form a cysteine-penicillamine disulfide complex, which is 50 times more soluble than cystine itself. (Tiopronin is another similar drug used). **NEET-PG High-Yield Pearls:** * **Pathognomonic sign:** Hexagonal (benzene ring-shaped) crystals on urine microscopy. * **Diagnosis:** Positive **Cyanide-Nitroprusside test** (urine turns cherry red). * **Stone Radiopacity:** Cystine stones are "faintly radiopaque" due to their sulfur content (often described as having a "ground-glass" appearance). * **Mnemonic for Transporter:** **COAL** (Cystine, Ornithine, Arginine, Lysine).

Question 543: Rapidly progressive glomerulonephritis (RPGN) occurs in all of the following conditions EXCEPT:

A. Systemic lupus erythematosus (SLE)
B. Post-streptococcal glomerulonephritis
C. Diabetic nephropathy (Correct Answer)
D. Goodpasture's syndrome

Explanation: **Explanation:** **Rapidly Progressive Glomerulonephritis (RPGN)** is a clinical syndrome characterized by a rapid decline in renal function (usually a 50% decline in GFR within weeks to months) and the histological presence of **crescents** in more than 50% of glomeruli [1]. **Why Diabetic Nephropathy is the Correct Answer:** Diabetic nephropathy is a **chronic, progressive** microvascular complication of diabetes [1]. It typically follows a predictable, slow course over years, starting with hyperfiltration, progressing to microalbuminuria, and eventually leading to overt proteinuria and Chronic Kidney Disease (CKD). It does not present with the acute, fulminant nephritic picture or crescent formation characteristic of RPGN. **Analysis of Incorrect Options:** * **SLE (Option A):** Class IV Lupus Nephritis (Diffuse Proliferative GN) is a classic cause of Type II (Immune-complex mediated) RPGN [1]. * **Post-streptococcal GN (Option B):** While most cases resolve, a small percentage of patients (especially adults) can develop a severe "crescentic" transformation, leading to RPGN [1]. * **Goodpasture’s Syndrome (Option D):** This is the prototype for Type I RPGN, caused by anti-glomerular basement membrane (anti-GBM) antibodies [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Classification of RPGN:** * **Type I:** Anti-GBM (e.g., Goodpasture’s) – Linear IF pattern [1]. * **Type II:** Immune Complex (e.g., SLE, PSGN, IgA Nephropathy, HSP) – Granular IF pattern [1]. * **Type III:** Pauci-immune (e.g., Wegener’s/GPA, Microscopic Polyangiitis) – ANCA associated; negative IF. * **Histology:** The "Crescents" are formed by the proliferation of **parietal epithelial cells** and the infiltration of monocytes/macrophages into Bowman’s space [1]. * **Diabetic Nephropathy Hallmark:** Kimmelstiel-Wilson (KW) nodules (nodular glomerulosclerosis).

Question 544: All of the following are used to remove potassium in hyperkalemia except?

A. Cation exchange resins
B. Diuretics
C. Beta 2 agonists (Correct Answer)
D. Dialysis

Explanation: To manage hyperkalemia, treatments are categorized into three mechanisms: **membrane stabilization** (Calcium gluconate), **intracellular shifting**, and **actual removal** of potassium from the body. [1] ### **Explanation of the Correct Answer** **Option C (Beta 2 agonists)** is the correct answer because it does **not** remove potassium from the body. Instead, it works by **intracellular shifting**. [2] Beta-2 agonists (like Albuterol/Salbutamol) stimulate the Na+/K+-ATPase pump, driving potassium from the extracellular fluid into the cells. [2] While this rapidly lowers serum potassium levels, the total body potassium remains unchanged. [2] ### **Analysis of Incorrect Options (Methods that REMOVE Potassium)** * **A. Cation exchange resins:** (e.g., Sodium Polystyrene Sulfonate, Patiromer) These work in the gastrointestinal tract by exchanging sodium or calcium for potassium ions, which are then excreted in the feces. * **B. Diuretics:** Loop diuretics (e.g., Furosemide) and Thiazides increase potassium excretion through the kidneys by inhibiting sodium reabsorption and increasing distal tubular flow. [3] * **D. Dialysis:** Hemodialysis is the most definitive and rapid method for the physical removal of potassium from the blood, typically reserved for refractory or life-threatening hyperkalemia. ### **NEET-PG High-Yield Pearls** * **The "Shift" Agents:** Insulin (with glucose) and Beta-2 agonists are the mainstays for shifting potassium intracellularly. [2] * **First Step in Management:** If ECG changes (like peaked T-waves) are present, the first step is **Calcium Gluconate** to stabilize the cardiac membrane (it does not lower K+ levels). [1] * **Definitive Treatment:** Dialysis is the "gold standard" for potassium removal in patients with renal failure. * **Caution:** Avoid Beta-2 agonists in patients with active coronary ischemia as they can cause tachycardia.

Question 545: Which of the following is NOT true about Bartter syndrome?

A. Causes hypokalemic alkalosis (Correct Answer)
B. Presents in neonates with ototoxicity and has a BSNDM2 gene mutation
C. Involves decreased potassium absorption from the thick ascending limb
D. Is inherited in an autosomal recessive pattern

Explanation: The correct answer is **A (Causes hypokalemic alkalosis)** because the question asks for the statement that is **NOT** true. This is a "negative" question; while Bartter syndrome *does* cause hypokalemic metabolic alkalosis, the statement itself is a true clinical feature, making it a "wrong" choice for a "NOT true" question. ### **Explanation of Options** * **Option A (Incorrect Statement for this question):** Bartter syndrome is characterized by **hypokalemic metabolic alkalosis** with normal to low blood pressure [1]. This occurs because the defect in the Thick Ascending Limb (TAL) mimics a permanent "loop diuretic" effect, leading to increased distal delivery of sodium and subsequent potassium/hydrogen ion secretion. * **Option B (False Statement/Correct Answer):** This is the "NOT true" statement. While Bartter Syndrome Type IV (caused by **BSND gene** mutations) presents with neonatal salt wasting and **sensorineural deafness**, there is no such entity as a "BSNDM2" gene mutation. * **Option C (True Statement):** The primary defect in Bartter syndrome is the failure of the **NKCC2 transporter** (or related channels like ROMK) in the TAL. Since the TAL is responsible for roughly 25-30% of sodium and potassium reabsorption, a defect here significantly decreases potassium absorption. * **Option D (True Statement):** Most forms of Bartter syndrome (Types I-IV) are inherited in an **autosomal recessive** pattern. ### **Clinical Pearls for NEET-PG** * **Bartter vs. Gitelman:** Bartter syndrome mimics **Loop Diuretics** (TAL defect, hypercalciuria); Gitelman syndrome mimics **Thiazides** (Distal Tubule defect, hypocalciuria). * **Hypercalciuria:** A key differentiator for Bartter is increased urinary calcium, which can lead to nephrocalcinosis. * **Antenatal Bartter:** Often presents with polyhydramnios and premature delivery.

Question 546: A client with chronic renal failure who is scheduled for hemodialysis this morning is due to receive a daily dose of enalapril (Vasotec). When should the nurse plan to administer this medication?

A. Just before dialysis
B. During dialysis
C. On return from dialysis (Correct Answer)
D. The day after dialysis

Explanation: ### Explanation **1. Why "On return from dialysis" is correct:** The timing of medication administration in patients undergoing hemodialysis (HD) is governed by two primary factors: **dialyzability** and **hemodynamic stability**. * **Dialyzability:** Enalapril is an ACE inhibitor that is significantly removed by the dialysis process (approximately 35-50%). Administering it before or during the procedure would result in the drug being filtered out, leading to sub-therapeutic levels. * **Hemodynamic Stability:** Hemodialysis involves rapid fluid removal (ultrafiltration), which often causes transient hypotension. ACE inhibitors interfere with the body's compensatory renin-angiotensin-aldosterone system (RAAS) response, significantly increasing the risk of severe **intradialytic hypotension**. Therefore, it is safest to administer the dose after the procedure once the patient is hemodynamically stable. **2. Why the other options are incorrect:** * **A & B (Before/During):** These options risk both drug washout (reducing efficacy) and profound hypotension during the session. * **D (The day after):** Chronic renal failure requires consistent blood pressure control. Skipping a daily dose entirely until the next day would lead to rebound hypertension and inadequate cardioprotection [1]. **3. Clinical Pearls for NEET-PG:** * **High-Yield Rule:** Always check the "Dialyzability" of a drug. Common drugs removed by HD include **Water-soluble vitamins (B, C), Lithium, Ethambutol, and many Antibiotics (e.g., Aminoglycosides).** * **Antihypertensives:** Most are held before HD to prevent hypotension, regardless of dialyzability. * **Exception:** Drugs that are highly protein-bound or lipid-soluble (e.g., Digoxin, Amiodarone, Warfarin) are generally **not** removed by dialysis. * **ACEi Specifics:** Enalapril is a pro-drug converted to enalaprilat; both are cleared by HD. Additionally, ACE inhibitors can rarely cause "anaphylactoid reactions" if used with high-flux polyacrylonitrile (AN69) dialysis membranes. ACE inhibitors have been shown to reduce the risk of cardiovascular events and all-cause mortality in CKD [1].

Question 547: A 24-year-old woman has dipstick-positive results for blood in her urine, which have been repeated twice between menstrual periods and remain positive. Microscopic evaluation reveals RBCs, some of which are deformed and some are in the form of casts. Which of the following is the most likely cause of the hematuria?

A. Urinary tract stones
B. Glomerulonephritis (Correct Answer)
C. Trauma
D. Benign renal tumor

Explanation: ### Explanation The presence of **dysmorphic RBCs** and **RBC casts** on microscopic urinalysis is the hallmark of **glomerular hematuria** [1]. **1. Why Glomerulonephritis is Correct:** In glomerulonephritis, red blood cells leak through a damaged glomerular basement membrane (GBM). As they pass through the narrow gaps in the GBM and travel through the tubular system, they undergo mechanical stress and osmotic changes, leading to **deformed (dysmorphic) shapes**, such as acanthocytes [3]. Furthermore, when RBCs are trapped within the renal tubules by Tamm-Horsfall protein, they form **RBC casts**. The presence of these casts is pathognomonic for a renal parenchymal source, specifically the glomerulus [1]. **2. Why Other Options are Incorrect:** * **A. Urinary tract stones:** These cause "extra-glomerular" or "post-renal" hematuria [2]. While they cause significant bleeding, the RBCs remain **isomorphic** (uniform in shape) because they do not pass through the nephron. Casts are never seen. * **C. Trauma:** Similar to stones, trauma causes bleeding from the macroscopic rupture of vessels in the kidney, ureter, or bladder [1]. This results in intact, normal-appearing RBCs. * **D. Benign renal tumor:** Tumors (like angiomyolipoma) cause hematuria through direct vascular erosion. This is a non-glomerular source characterized by isomorphic RBCs and an absence of casts [2]. **Clinical Pearls for NEET-PG:** * **Acanthocytes:** RBCs with "mickey mouse ear" protrusions; >5% acanthocytes is highly suggestive of glomerular disease. * **RBC Casts:** Always indicate a renal origin (Glomerulonephritis or Vasculitis). * **Dipstick vs. Microscopy:** Dipstick detects hemoglobin (via peroxidase activity) but cannot differentiate between intact RBCs, free hemoglobin, or myoglobin [1]. Microscopy is essential to confirm hematuria. * **Initial vs. Terminal Hematuria:** Initial hematuria usually suggests a urethral source; terminal suggests the bladder neck or prostate; total hematuria suggests the bladder or upper urinary tract.

Question 548: A plasma urea to creatinine ratio of 20:1 may be seen in which of the following conditions?

A. Rhabdomyolysis
B. Ureteric calculi
C. Pre-renal failure (Correct Answer)
D. Chronic glomerulonephritis

Explanation: ### Explanation The normal plasma urea-to-creatinine ratio is typically between **10:1 and 15:1**. A ratio exceeding **20:1** is a classic biochemical marker for **Pre-renal Azotemia**. **Why Pre-renal failure is correct:** In pre-renal states (e.g., dehydration, heart failure, or hemorrhage), renal perfusion decreases [1]. This triggers the activation of the Renin-Angiotensin-Aldosterone System (RAAS). Increased proximal tubular reabsorption of sodium and water occurs, and because **urea** follows water passively, its reabsorption into the blood increases significantly [1]. In contrast, **creatinine** is not reabsorbed and is primarily excreted via filtration and minimal secretion. This disproportionate rise in blood urea relative to creatinine results in a ratio >20:1. **Analysis of Incorrect Options:** * **Rhabdomyolysis:** This causes a **low** urea-to-creatinine ratio. Massive muscle breakdown releases large amounts of endogenous creatinine into the blood, often resulting in a ratio <10:1. * **Ureteric calculi (Post-renal):** In early obstructive uropathy, both urea and creatinine are elevated proportionally, maintaining a ratio between 10:1 and 20:1. * **Chronic Glomerulonephritis (Intrinsic renal):** In intrinsic renal disease, the tubules are damaged and cannot reabsorb urea effectively. Both urea and creatinine rise in tandem as GFR falls, typically maintaining a "normal" ratio of 10:1. **High-Yield Clinical Pearls for NEET-PG:** * **Fractional Excretion of Sodium (FeNa):** <1% in Pre-renal; >2% in Acute Tubular Necrosis (ATN). * **Urinary Osmolality:** >500 mOsm/kg in Pre-renal (concentrated urine); <350 mOsm/kg in ATN (dilute urine) [1]. * **Other causes of high ratio (>20:1):** GI bleed (breakdown of blood proteins), high protein diet, and treatment with steroids (increased catabolism).

Question 549: Which of the following conditions is characterized by hyperchloremic acidosis with hypokalemia?

A. Renal tubular acidosis (Correct Answer)
B. Addison's disease
C. Pyloric stenosis
D. Primary hyperaldosteronism

Explanation: **Explanation:** The hallmark of **Renal Tubular Acidosis (RTA)** is a **Normal Anion Gap Metabolic Acidosis (NAGMA)**, also known as hyperchloremic metabolic acidosis. In RTA (specifically Types 1 and 2), the kidneys fail to either reabsorb bicarbonate or excrete hydrogen ions. To maintain electroneutrality in the blood when bicarbonate is lost, chloride levels rise, leading to hyperchloremia. **Hypokalemia** occurs because the distal delivery of sodium leads to increased sodium-potassium exchange (Type 1) or because of proximal bicarbonate wasting (Type 2). **Analysis of Incorrect Options:** * **Addison’s Disease:** Characterized by mineralocorticoid deficiency, leading to hyperkalemia and metabolic acidosis (Type 4 RTA-like picture), not hypokalemia. * **Pyloric Stenosis:** Causes loss of gastric HCl, resulting in **Hypochloremic Metabolic Alkalosis** with hypokalemia (due to vomiting). * **Primary Hyperaldosteronism:** Excess aldosterone causes sodium retention and potassium/hydrogen excretion, leading to **Metabolic Alkalosis** and hypokalemia, not acidosis. **High-Yield Clinical Pearls for NEET-PG:** * **Type 1 RTA (Distal):** Inability to secrete $H^+$. Associated with urine $pH > 5.5$, hypokalemia, and nephrolithiasis. * **Type 2 RTA (Proximal):** Inability to reabsorb $HCO_3^-$. Associated with hypokalemia and Fanconi syndrome. * **Type 4 RTA (Hyperkalemic):** Associated with aldosterone deficiency or resistance (e.g., Diabetes Mellitus). It is the **only** RTA with **hyperkalemia**. * **Mnemonic:** "Hardup" or "Used Car" for NAGMA causes (Ureterosigmoidostomy, Saline, Endocrine, Diarrhea, **RTA**, Carbonic anhydrase inhibitors).

Question 550: A 47-year-old HIV-positive man presents with weakness. He has HIV nephropathy and adrenal insufficiency, and takes trimethoprim-sulfamethoxazole for PCP prophylaxis and triple-agent antiretroviral treatment. He was recently started on spironolactone for ascites due to alcoholic liver disease. Physical examination reveals normal vital signs, but his muscles are diffusely weak. Frequent extrasystoles are noted. He has mild ascites and 1+ peripheral edema. Laboratory studies show a serum creatinine of 2.5 mg/dL with a potassium value of 7.3 mEq/L. ECG shows peaking of the T-waves and QRS widening to 0.14 seconds. What is the most important immediate treatment for this patient's hyperkalemia?

A. Sodium polystyrene sulfonate (Kayexalate)
B. Acute hemodialysis
C. IV normal saline
D. IV calcium gluconate (Correct Answer)

Explanation: **Explanation:** The patient presents with severe, life-threatening hyperkalemia (7.3 mEq/L) complicated by **ECG changes** (peaked T-waves, QRS widening) [1] and neuromuscular symptoms (weakness). In the setting of hyperkalemia with ECG changes or a potassium level >6.5 mEq/L, the immediate priority is **membrane stabilization** [1]. **1. Why IV Calcium Gluconate is correct:** Hyperkalemia increases the resting membrane potential of myocytes [2], bringing it closer to the threshold potential, which leads to myocardial excitability and potential cardiac arrest. **IV Calcium Gluconate** (or Calcium Chloride) antagonizes the membrane effects of hyperkalemia by shifting the threshold potential, thereby stabilizing the cardiac membrane [1]. It does **not** lower serum potassium levels but acts within minutes to prevent fatal arrhythmias. **2. Why other options are incorrect:** * **Sodium polystyrene sulfonate (Kayexalate):** This is a cation exchange resin used for slow removal of potassium via the GI tract. It is not indicated for emergency management as it takes hours to work and carries a risk of bowel necrosis. * **Acute hemodialysis:** While this is the most definitive way to remove potassium (especially in a patient with renal failure/Cr 2.5), it takes time to initiate. Membrane stabilization must come first. * **IV Normal Saline:** This is used for volume expansion but has no role in the acute stabilization of hyperkalemic cardiotoxicity. **Clinical Pearls for NEET-PG:** * **The "Rule of Three" for Hyperkalemia Management:** 1. **Stabilize** (Calcium Gluconate), 2. **Shift** (Insulin + Glucose, Beta-agonists, Sodium Bicarbonate), 3. **Remove** (Diuretics, Resins, Dialysis). * **Drug-induced Hyperkalemia:** Note this patient’s risk factors: **Trimethoprim** (blocks apical sodium channels in the distal tubule), **Spironolactone** (K-sparing diuretic), and **HIV Nephropathy** (CKD). * **ECG Progression:** Peaked T waves → PR prolongation/P wave flattening → QRS widening → Sine wave pattern → VF/Asystole [1].

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Nephrology — MCQs

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