Nephrology Practice Questions

Q: In tubular necrosis, what is the ratio of urine to plasma creatinine?

20. In clinical nephrology, the **Urine to Plasma (U/P) Creatinine ratio** is a critical diagnostic marker used to differentiate between **Prerenal Azotemia** and **Acute Tubular Necrosis (ATN)**. [1] ### **Explanation of the Correct Answer** In **Acute Tubular Necrosis (ATN)**, the tubular epithelial cells are damaged and lose their ability to concentrate urine and reabsorb water. Because the tubules cannot effectively reabsorb water, the creatinine in the tubular fluid is not concentrated. Consequently, the ratio of creatinine in the urine compared to the plasma remains low. A **U/P Creatinine ratio of 40** is characteristic of **Prerenal Azotemia**. In this state, the tubular function is intact; the kidneys respond to hypoperfusion by maximizing water reabsorption, which significantly concentrates the creatinine in the urine. * **Options C and D (20-30 and 30-40):** These ranges represent an intermediate or "gray zone." While values between 20 and 40 can occur in evolving clinical states, they are not the classic diagnostic threshold for ATN in standardized examinations. ### **NEET-PG High-Yield Pearls** To distinguish Prerenal Azotemia from ATN, remember these classic parameters: | Parameter | Prerenal Azotemia | Acute Tubular Necrosis (ATN) | | :--- | :--- | :--- | | **U/P Creatinine Ratio** | **> 40** | ** 2% | | **Urine Sodium (UNa)** | 40 mEq/L | | **Urine Osmolality** | > 500 mOsm/kg | < 350 mOsm/kg | | **Urinary Sediment** | Hyaline casts | **Muddy brown granular casts** |

Q: Dialysis disequilibrium syndrome is primarily caused by which of the following phenomena?

Cerebral edema. **Explanation:** **Dialysis Disequilibrium Syndrome (DDS)** is a clinical phenomenon characterized by neurological symptoms (headache, nausea, seizures, or coma) occurring during or shortly after hemodialysis, particularly in patients with high baseline urea levels receiving their first treatment. **Why Cerebral Edema is the Correct Answer:** The primary pathophysiology is the **"Reverse Urea Effect."** During rapid hemodialysis, urea is cleared quickly from the blood but much more slowly from the brain tissue due to the blood-brain barrier. This creates an **osmotic gradient** that draws water from the intravascular compartment into the brain cells, leading to **cerebral edema** and increased intracranial pressure. **Analysis of Incorrect Options:** * **A. Hypovolemia:** While common during dialysis due to ultrafiltration, hypovolemia causes hypotension and cramps, not the specific neurological symptoms of DDS. * **B. Use of bicarbonate-containing dialysate:** Bicarbonate is the standard buffer used today. While rapid correction of metabolic acidosis can theoretically shift the oxyhemoglobin curve, it is not the primary driver of the osmotic shifts seen in DDS. * **D. Hypokalemia:** Rapid shifts in potassium can lead to cardiac arrhythmias or muscle weakness, but they do not cause the cerebral swelling characteristic of DDS. **High-Yield Clinical Pearls for NEET-PG:** * **Risk Factors:** High pre-dialysis BUN (>150 mg/dL), first-ever dialysis session, and aggressive/high-flux dialysis. * **Prevention:** The most effective strategy is to use a **slow blood flow rate**, shorter treatment duration for the first session, and sometimes the addition of osmotically active substances like **mannitol** to prevent rapid osmotic shifts. * **Management:** If DDS occurs, the dialysis must be slowed or stopped immediately.

Q: All of the following are used for the treatment of hyperkalemia except?

Beta blockers. ### Explanation The management of hyperkalemia focuses on three goals: stabilizing the cardiac membrane, shifting potassium into cells, and removing potassium from the body [1]. **Why Beta-blockers are the correct answer:** Beta-blockers (specifically non-selective ones) **worsen** hyperkalemia. Under normal physiological conditions, Beta-2 receptors stimulate the Na+/K+-ATPase pump, which moves potassium into the intracellular compartment [3]. Beta-blockers inhibit this process, preventing the cellular uptake of potassium. In contrast, **Beta-agonists** (like inhaled Salbutamol) are used as a treatment to lower serum potassium. **Analysis of other options:** * **Calcium gluconate:** This is the first-line treatment for hyperkalemia with ECG changes. It does not lower potassium levels but **stabilizes the cardiac myocyte membrane** by antagonizing the effect of potassium on the resting membrane potential [1]. * **Sodium bicarbonate:** This promotes an intracellular shift of potassium. As pH increases (alkalosis), H+ ions move out of the cell in exchange for K+ ions moving into the cell to maintain electroneutrality [3]. * **IV Glucose with Insulin:** Insulin is a potent stimulator of the Na+/K+-ATPase pump. Glucose is co-administered to prevent hypoglycemia. This is the most reliable method to rapidly shift potassium intracellularly. **NEET-PG High-Yield Pearls:** 1. **Membrane Stabilizer:** Calcium gluconate (acts within 1-3 mins; duration 30-60 mins) [1]. Note: Use Calcium chloride if central venous access is available as it is more potent. 2. **Redistribution (Shifters):** Insulin + Dextrose, Beta-2 agonists, and Sodium Bicarbonate. 3. **Elimination (Excretors):** Loop diuretics (Furosemide), Cation exchange resins (Patiromer, Sodium Polystyrene Sulfonate), and Hemodialysis (most definitive). 4. **ECG Sequence:** Tall peaked T-waves → Prolonged PR interval → Loss of P-wave → Widened QRS → Sine wave pattern → Asystole [2].

Q: Which is the most common cause of this condition?

Diabetes. ***Diabetes*** - **Diabetic nephropathy** is the leading cause of **nephrotic syndrome** and **chronic kidney disease** in adults worldwide, especially in developing countries like India. - Long-term **hyperglycemia** leads to **glomerular basement membrane thickening** and **mesangial expansion**, resulting in proteinuria and eventual kidney failure. *Berger Disease* - **IgA nephropathy** is the most common cause of **glomerulonephritis** but typically presents with **nephritic syndrome** (hematuria, hypertension). - It rarely causes **nephrotic syndrome** and is more common in younger patients with recurrent **gross hematuria** following upper respiratory infections. *Aortic Embolism* - **Renal artery embolism** causes **acute kidney injury** with **flank pain** and **hematuria**, not nephrotic syndrome. - Results in **acute renal infarction** rather than chronic **proteinuria** and **hypoalbuminemia** seen in nephrotic syndrome. *Dissection of aorta* - **Aortic dissection** may cause **acute renal failure** if it involves the **renal arteries**, but does not cause nephrotic syndrome. - Presents with **severe chest/back pain**, **pulse deficits**, and **hypertensive emergency**, not chronic proteinuria.

Q: Increased anion gap is a characteristic feature of which condition?

Phenformin toxicity with coma. **Explanation:** The **Anion Gap (AG)** is calculated as $[Na^+] - ([Cl^-] + [HCO_3^-])$. An increased anion gap indicates the presence of unmeasured metabolic acids in the blood [1]. **Why Option C is Correct:** **Phenformin** (a biguanide similar to metformin, but with a much higher risk profile) causes **Lactic Acidosis**. It interferes with mitochondrial oxidative phosphorylation and inhibits gluconeogenesis, leading to the accumulation of lactate [1]. Since lactate is an unmeasured anion, it replaces bicarbonate, resulting in a **High Anion Gap Metabolic Acidosis (HAGMA)**. **Analysis of Incorrect Options:** * **A. Hyperosmolar Non-Ketotic Coma (HONK/HHS):** Characterized by extreme hyperglycemia and hyperosmolarity without significant ketone production. Because there is enough insulin to prevent lipolysis, ketoacids do not accumulate; thus, the anion gap is typically normal or only minimally elevated. * **B. Hypoglycaemic Coma:** This is a metabolic emergency due to low fuel substrate for the brain. It does not inherently involve the accumulation of organic acids, so the anion gap remains normal. * **D. Renal Tubular Acidosis (RTA):** This is a classic cause of **Normal Anion Gap Metabolic Acidosis (NAGMA)** or hyperchloremic acidosis [1]. The drop in bicarbonate is compensated for by a proportional increase in chloride. **NEET-PG High-Yield Pearls:** * **Mnemonic for HAGMA:** **MUDPILES** (Methanol, Uremia, DKA, Propylene glycol, Iron/INH, **Lactic acidosis**, Ethylene glycol, Salicylates). * **Mnemonic for NAGMA:** **HARDUP** (Hyperalimentation, Acetazolamide, **RTA**, Diarrhea, Uretero-sigmoidostomy, Pancreatic fistula). * **Clinical Note:** Phenformin was withdrawn in many countries due to this specific risk of fatal lactic acidosis; Metformin carries a much lower risk but is still contraindicated in severe renal failure [1].

Q: Hypomagnesemia is associated with which of the following electrolyte imbalances?

Hypokalemia. **Explanation:** **Why Hypokalemia is the correct answer:** Hypomagnesemia is a frequent cause of refractory hypokalemia. The underlying mechanism involves the **ROMK (Renal Outer Medullary Potassium) channels** in the distal nephron. Under normal physiological conditions, intracellular magnesium acts as a "plug," inhibiting the excessive efflux of potassium through these channels. When magnesium levels are low, this inhibitory effect is lost, leading to uncontrolled potassium secretion into the urine. Consequently, hypokalemia cannot be corrected until the magnesium deficiency is addressed. **Analysis of Incorrect Options:** * **A. Hypercalcemia:** Incorrect. Hypomagnesemia is actually associated with **hypocalcemia**. Low magnesium levels impair the release of Parathyroid Hormone (PTH) and induce skeletal resistance to PTH action. * **C. Hyperkalemia:** Incorrect. As explained above, low magnesium promotes potassium wasting, leading to low serum potassium, not high. * **D. Hyperphosphatemia:** Incorrect. There is no direct causal link between isolated hypomagnesemia and elevated phosphate levels. **Clinical Pearls for NEET-PG:** * **Refractory Hypokalemia:** Always check magnesium levels in patients whose potassium levels do not rise despite adequate supplementation. * **ECG Changes:** Hypomagnesemia presents similarly to hypokalemia (prolonged QT, flattened T waves, and presence of U waves). * **Torsades de Pointes:** Magnesium sulfate is the drug of choice for this specific arrhythmia, often triggered by electrolyte imbalances. * **Digoxin Toxicity:** Hypomagnesemia predisposes patients to digoxin toxicity, similar to hypokalemia.

Question 1

In tubular necrosis, what is the ratio of urine to plasma creatinine?

Accepted Answer

20

Answer

40

Answer

20-30

Answer

30-40

Question 2

Dialysis disequilibrium syndrome is primarily caused by which of the following phenomena?

Accepted Answer

Cerebral edema

Answer

Hypovolemia

Answer

Use of bicarbonate-containing dialysate

Answer

Hypokalemia

Question 3

All of the following are used for the treatment of hyperkalemia except?

Accepted Answer

Beta blockers

Answer

Calcium gluconate

Answer

Sodium bicarbonate

Answer

Intravenous infusion of glucose with insulin

Question 4

Which is the most common cause of this condition?

Accepted Answer

Diabetes

Answer

Berger Disease

Answer

Aortic Embolism

Answer

Dissection of aorta

Question 5

A 30-year-old man presents with generalized edema and hypertension. Urine examination shows subnephrotic proteinuria (< 2gm) and microscopic hematuria. Serum complement levels are decreased and he is positive for anti-hepatitis C antibodies. What is the most likely diagnosis?

Accepted Answer

IgA Nephropathy

Answer

Post streptococcal Glomerulonephritis (PSGN)

Answer

Cryoglobulinemia

Answer

Membranoproliferative Glomerulonephritis (MPGN)

Question 6

The triad of hematuria, hypertension, and edema is a characteristic feature of which condition?

Accepted Answer

Acute Glomerulonephritis

Answer

Acute Pyelonephritis

Answer

Chronic Glomerulonephritis

Answer

Renal cell carcinoma

Question 7

Increased anion gap is a characteristic feature of which condition?

Accepted Answer

Phenformin toxicity with coma

Answer

Hyperosmolar non-ketotic diabetic coma

Answer

Hypoglycaemic coma

Answer

Renal tubular acidosis

Question 8

All of the following are seen in Hemolytic Uremic Syndrome (HUS) except?

Accepted Answer

Altered sensorium

Answer

Thrombocytopenia

Answer

Hemolytic anemia

Answer

Renal failure

Question 9

Which of the following symptoms do you expect to see in a patient diagnosed with acute pyelonephritis?

Accepted Answer

Costovertebral angle tenderness and chills

Answer

Jaundice and flank pain

Answer

Burning sensation on urination

Answer

Polyuria and nocturia

Question 10

Hypomagnesemia is associated with which of the following electrolyte imbalances?

Accepted Answer

Hypokalemia

Answer

Hypercalcemia

Answer

Hyperkalemia

Answer

Hyperphosphatemia

Nephrology — MCQs

Nephrology — MCQs

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