Nephrology Practice Questions

Q: A 65-year-old man has urine output of 10 mL/h following abdominal aortic aneurysmectomy. Acute tubular necrosis is suggested by the presence of which of the following?

Urine sodium of more than 40 mEq/L. **Explanation:** The clinical scenario describes oliguria following major surgery [1], suggesting a transition from **Prerenal Azotemia** (due to hypovolemia or cross-clamping of the aorta) to **Intrinsic Acute Kidney Injury (Acute Tubular Necrosis - ATN)**. **Why Option B is Correct:** In ATN, the tubular epithelial cells are damaged and lose their ability to reabsorb sodium and concentrate urine. Consequently, a large amount of sodium is "wasted" in the urine. A **Urine Sodium >40 mEq/L** is a hallmark of ATN, indicating tubular dysfunction. **Why the Other Options are Incorrect:** * **Option A (Urine Osmolality >500 mOsm/kg):** This indicates intact tubular concentrating ability, characteristic of **Prerenal Azotemia**. In ATN, the urine is iso-osmolar with plasma (typically 2%**. * **Option D (BUN:SCr Ratio >20):** A high ratio (>20:1) is seen in **Prerenal Azotemia** due to increased urea reabsorption in the proximal tubule alongside water. In ATN, the ratio is typically normal (**10-15:1**) because both BUN and Creatinine are handled similarly by the damaged tubules. **High-Yield Clinical Pearls for NEET-PG:** * **Microscopy:** Look for **"Muddy Brown" granular casts** or renal tubular epithelial cell casts in ATN. * **Exception to FE_Na:** FE_Na can be <1% in certain types of ATN, such as those induced by **contrast media, rhabdomyolysis, or sepsis**. * **Urine Specific Gravity:** In ATN, it is fixed at **1.010** (isosthenuria), reflecting the loss of concentrating capacity.

Q: What is the complication of the diuretic phase of acute renal failure?

Increased sodium excretion in urine. ### Explanation In the recovery phase of Acute Kidney Injury (AKI), specifically the **diuretic phase**, the kidneys regain their ability to filter blood before they regain the ability to concentrate urine or reabsorb electrolytes effectively. **Why Option C is Correct:** During this phase, the glomerular filtration rate (GFR) begins to normalize, but the newly regenerated tubular epithelial cells are still immature and lack full resorptive capacity [1]. This leads to an "osmotic diuresis" driven by the high levels of accumulated urea and a failure of the tubules to reabsorb sodium [4]. Consequently, there is a massive loss of water and **increased sodium excretion in the urine**, which can lead to profound dehydration and hyponatremia [2]. **Analysis of Incorrect Options:** * **A. Convulsion:** While severe electrolyte imbalances can cause seizures, they are more commonly associated with the uremic state of the *oliguric phase* or rapid shifts during dialysis (Dialysis Disequilibrium Syndrome) [3]. * **B. Hyperkalemia:** This is a hallmark of the *oliguric phase*. In the diuretic phase, the primary risk is actually **hypokalemia** due to excessive potassium loss in the urine. * **D. Metabolic Alkalosis:** AKI typically presents with High Anion Gap Metabolic Acidosis (HAGMA) [3]. While recovery occurs, metabolic alkalosis is not a standard complication of the diuretic phase unless there is external intervention (like excessive bicarbonate therapy). **High-Yield Clinical Pearls for NEET-PG:** * **Diuretic Phase Risk:** The most common cause of death in this phase is **hypokalemia** and secondary infections. * **Urine Output:** Can reach 4–5 Liters/day. * **Sequence of Recovery:** GFR recovers first $\rightarrow$ Tubular function (concentration/dilution) recovers last. * **Management:** Meticulous fluid and electrolyte replacement (especially $K^+$ and $Na^+$) is critical during this transition [1].

Q: Sensorineural deafness may be a feature of all of the following conditions, EXCEPT?

Nail-patella syndrome. **Explanation:** The correct answer is **Nail-patella syndrome (Option C)**. This is an autosomal dominant condition caused by mutations in the **LMX1B gene**. While it is characterized by the clinical tetrad of nail hypoplasia/dysplasia, absent or hypoplastic patellae, iliac horns (pathognomonic), and elbow abnormalities, it is **not** associated with sensorineural hearing loss (SNHL). Renal involvement occurs in about 40% of cases, typically presenting as proteinuria or focal segmental glomerulosclerosis (FSGS). **Analysis of other options:** * **Alport Syndrome (Option A):** A classic cause of hereditary nephritis due to mutations in Type IV collagen (COL4A3/4/5). The most common extra-renal manifestation is **bilateral sensorineural deafness** (high-frequency), alongside ocular defects like anterior lenticonus. * **Batten Disease (Option B):** Also known as Neuronal Ceroid Lipofuscinosis (NCL), this group of neurodegenerative disorders involves the accumulation of lipopigments. While primarily causing vision loss and seizures, certain subtypes are associated with progressive hearing impairment. * **Distal Renal Tubular Acidosis (Type 1 RTA) (Option D):** Specifically, the autosomal recessive form of distal RTA (associated with mutations in *ATP6V1B1* or *ATP6V0A4*) is frequently associated with **early-onset sensorineural hearing loss** [1]. **NEET-PG High-Yield Pearls:** * **Iliac Horns:** Pathognomonic radiological sign for Nail-patella syndrome. * **Alport Syndrome:** Look for the

Q: Which is not a feature of classic distal renal tubular acidosis?

Hyperkalemia. ### Explanation **Distal Renal Tubular Acidosis (Type 1 RTA)** is characterized by a defect in the alpha-intercalated cells of the distal tubule, leading to an inability to secrete hydrogen ions ($H^+$) [1]. **1. Why Hyperkalemia is the correct answer:** In classic Type 1 RTA, the primary defect is the failure of the $H^+$-ATPase pump. To maintain electrical neutrality, the kidney excretes potassium ($K^+$) instead of hydrogen ions. This results in **hypokalemia**, not hyperkalemia. Hyperkalemia is a hallmark of **Type 4 RTA** (Hypoaldosteronism), making it the "odd one out" for distal RTA. **2. Analysis of Incorrect Options:** * **Urine pH > 5.5:** This is the most characteristic feature [1]. Because the distal tubule cannot secrete $H^+$, the urine cannot be acidified below a pH of 5.5, even in the presence of systemic acidemia [1]. * **Positive Urine Anion Gap (UAG):** UAG ($Na + K - Cl$) is a surrogate marker for urinary ammonium ($NH_4^+$) excretion. In Type 1 RTA, $NH_4^+$ production is impaired due to the distal defect, leading to a low chloride concentration and a **positive** UAG. * **Nephrocalcinosis:** Chronic acidemia leads to bone resorption (releasing calcium) and inhibits citrate reabsorption. The combination of hypercalciuria and hypocitraturia in alkaline urine causes calcium phosphate stones and medullary nephrocalcinosis. **Clinical Pearls for NEET-PG:** * **Type 1 (Distal):** Hypokalemia, Urine pH > 5.5, Stones (Nephrocalcinosis). * **Type 2 (Proximal):** Hypokalemia, Urine pH < 5.5 (eventually), associated with **Fanconi Syndrome**. * **Type 4 (Hyperkalemic):** Only RTA with **Hyperkalemia**; associated with Diabetes Mellitus and Addison’s disease. * **Mnemonic:** "Distal is **D**istant from 7 (pH is high/alkaline)" and "Type **4** adds **K** (Hyperkalemia)."

Q: Which of the following is characteristic of CRF?

Chronic Renal Failure (CRF). **Explanation:** The hallmark of **Chronic Renal Failure (CRF)**, now more commonly referred to as Chronic Kidney Disease (CKD), is the irreversible and progressive loss of nephron function over a period of at least three months. The characteristic features that distinguish CRF from acute conditions include **bilateral small, shrunken kidneys** (on ultrasound), **secondary hyperparathyroidism**, and **renal osteodystrophy**. The presence of broad waxy casts in urinary sediment is also a specific indicator of the dilated, hypertrophied nephrons seen in end-stage renal disease. **Analysis of Options:** * **Acute Glomerulonephritis (Ac GN):** This is characterized by the sudden onset of hematuria (coca-cola colored urine), hypertension, and edema. It is an inflammatory process, not a failure state, and is typically reversible. * **Acute Renal Failure (ARF/AKI):** ARF involves a rapid decline in GFR (hours to days). Key differentiators from CRF include **normal-sized kidneys** and the potential for full recovery of renal function once the underlying insult is removed. * **Renal Tuberculosis:** This typically presents with "sterile pyuria" (pus cells in urine without bacterial growth on routine culture) and characteristic imaging findings like infundibular stenosis or "putty kidney," rather than generalized renal failure. **NEET-PG High-Yield Pearls:** * **Kidney Size Exception:** While small kidneys are characteristic of CRF, certain conditions cause **CRF with large/normal kidneys**: Diabetes Mellitus (most common), Amyloidosis, Polycystic Kidney Disease (PCKD), and HIV-associated nephropathy. * **Anemia:** Normocytic normochromic anemia due to Erythropoietin deficiency is a classic sign of CRF. * **Electrolytes:** CRF typically presents with hypocalcemia, hyperphosphatemia, and hyperkalemia.

Q: Renal vein thrombosis is caused by all of the following except?

Lupus nephritis. **Explanation:** Renal Vein Thrombosis (RVT) occurs due to the classic Virchow’s triad: endothelial injury, stasis of blood flow, and hypercoagulability. **Why Lupus Nephritis is the correct answer (the "Except"):** While Lupus Nephritis (LN) is a glomerular disease, it is **not** a primary cause of RVT unless it progresses to **Nephrotic Syndrome** [1]. Among the nephrotic syndromes, RVT is most strongly associated with **Membranous Nephropathy (MN)** [2], followed by Minimal Change Disease and FSGS. LN itself, without the profound protein loss and loss of Antithrombin III seen in nephrotic states, does not typically cause RVT. **Analysis of Incorrect Options:** * **Invasive Renal Cell Carcinoma (RCC):** This is a classic cause of RVT due to direct **vascular invasion**. The tumor thrombus often extends into the renal vein and can reach the Inferior Vena Cava (IVC). * **Pregnancy:** Pregnancy is a systemic **hypercoagulable state** due to increased clotting factors and venous stasis from the gravid uterus compressing the IVC, increasing the risk of thromboembolic events, including RVT. * **Dehydration:** This is the most common cause of RVT in **neonates and infants**. Hemoconcentration leads to increased blood viscosity and stasis, triggering thrombus formation. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard Investigation:** Selective Renal Venography. * **Investigation of Choice (Non-invasive):** CT Angiography or Doppler Ultrasound. * **Clinical Presentation:** Flank pain, hematuria, and a sudden increase in proteinuria or decline in GFR. * **Most Common Association:** Membranous Nephropathy (up to 30-50% of patients may develop subclinical RVT) [2].

Q: What is the most common cause of hypovolemic hyponatremia in a hospitalized patient?

Diuretic-induced. ### Explanation **Correct Option: B. Diuretic-induced** Hypovolemic hyponatremia occurs when there is a loss of both water and sodium, but the sodium loss is disproportionately greater [1]. In hospitalized patients, **diuretics (especially Thiazides)** are the most common cause [1]. * **Mechanism:** Diuretics inhibit sodium reabsorption (Thiazides at the distal convoluted tubule; Loop diuretics at the Thick Ascending Limb). This leads to volume depletion, which triggers the non-osmotic release of **Antidiuretic Hormone (ADH)**. ADH causes water retention in the collecting ducts via V2 receptors and aquaporin channels, further diluting the serum sodium and resulting in hyponatremia [2]. **Analysis of Incorrect Options:** * **A. Intravenous fluids:** While common in hospitals, IV fluids (like 5% Dextrose) typically cause **euvolemic** hyponatremia due to the administration of free water, rather than hypovolemic hyponatremia [1]. * **C. Severe pain:** Pain, stress, and nausea are potent stimulators of ADH secretion (SIADH physiology). This leads to **euvolemic** hyponatremia, as there is no primary fluid volume deficit [1]. * **D. Congestive heart failure (CHF):** CHF is a classic cause of **hypervolemic** hyponatremia [1]. Despite low effective arterial blood volume, the total body water and sodium are increased (edematous state). **NEET-PG High-Yield Pearls:** * **Thiazides vs. Loop Diuretics:** Thiazides cause hyponatremia more frequently than Loop diuretics because they do not interfere with the medullary osmotic gradient, allowing ADH to work more effectively. * **Urinary Sodium Check:** In hypovolemic hyponatremia, if $U_{Na} 40$ mEq/L, the loss is renal (e.g., diuretics or Addison’s disease) [1]. * **Management:** The mainstay of treatment for hypovolemic hyponatremia is **Isotonic (0.9%) Saline** to restore volume and shut off the ADH stimulus [3].

Question 1

A 65-year-old man has urine output of 10 mL/h following abdominal aortic aneurysmectomy. Acute tubular necrosis is suggested by the presence of which of the following?

Accepted Answer

Urine sodium of more than 40 mEq/L

Answer

Urine osmolality of more than 500 mOsm/kg

Answer

Fractional excretion of sodium of <1%

Answer

Blood urea nitrogen (BUN)-to-serum creatinine ratio (SCR) of more than 20

Question 2

What is the complication of the diuretic phase of acute renal failure?

Accepted Answer

Increased sodium excretion in urine

Answer

Convulsion

Answer

Hyperkalemia

Answer

Metabolic Alkalosis

Question 3

Sensorineural deafness may be a feature of all of the following conditions, EXCEPT?

Accepted Answer

Nail-patella syndrome

Answer

Alport syndrome

Answer

Batten disease

Answer

Distal renal tubular acidosis

Question 4

Which is not a feature of classic distal renal tubular acidosis?

Accepted Answer

Hyperkalemia

Answer

Urine pH >5.5

Answer

Positive urine anion gap

Answer

Nephrocalcinosis

Question 5

Which of the following is characteristic of CRF?

Accepted Answer

Chronic Renal Failure (CRF)

Answer

Acute Glomerulonephritis (Ac GN)

Answer

Acute Renal Failure (ARF)

Answer

Renal Tuberculosis (Renal TB)

Question 6

In urinary system disease, gastrointestinal symptoms appear due to which phenomenon?

Accepted Answer

Renogastric reflex

Answer

Chemical reactions

Answer

Peritoneal reactions

Answer

Reflux phenomenon

Question 7

A 20-year-old female presents with a blood pressure of 160/110 mm Hg. Clinical examination reveals a bruit in both flanks. Which of the following statements about this patient is not true?

Accepted Answer

The condition is nearly always bilateral.

Answer

Enalapril may deteriorate renal function.

Answer

The most definitive diagnostic procedure is contrast-enhanced angiography.

Answer

Surgical intervention may be used.

Question 8

Renal vein thrombosis is caused by all of the following except?

Accepted Answer

Lupus nephritis

Answer

Invasive renal cell carcinoma

Answer

Pregnancy

Answer

Dehydration

Question 9

A 30-year-old male presents with hemoptysis, facial puffiness, microscopic hematuria, and increased serum creatinine. Which of the following investigations should be included?

Accepted Answer

Antinuclear antibody (ANA)

Answer

Chest X-ray

Answer

Antineutrophil cytoplasmic antibody (ANCA)

Answer

CT scan of the chest

Question 10

What is the most common cause of hypovolemic hyponatremia in a hospitalized patient?

Accepted Answer

Diuretic-induced

Answer

Intravenous fluids

Answer

Severe pain

Answer

Congestive heart failure

Nephrology — MCQs

Nephrology — MCQs

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