Nephrology Practice Questions

Q: What is the cause of hyperkalemia in chronic kidney failure?

Decreased excretion. The primary cause of hyperkalemia in Chronic Kidney Disease (CKD) is **decreased renal excretion**. Under normal physiological conditions, the kidneys are responsible for excreting approximately 90% of daily potassium intake [1]. As the Glomerular Filtration Rate (GFR) declines, the remaining functional nephrons initially compensate by increasing potassium secretion (mediated by aldosterone) [1]. However, once the GFR falls below **15–20 mL/min** (Stage 4/5 CKD), these compensatory mechanisms fail [3], leading to systemic potassium accumulation. **Analysis of Options:** * **A. Release from cells:** While intracellular shifts (e.g., in metabolic acidosis or rhabdomyolysis) can cause hyperkalemia [2], they are acute triggers rather than the primary underlying cause of the chronic state in CKD. * **B. Hyperinsulinemia:** Insulin actually promotes the shift of potassium *into* cells [2]. Therefore, hyperinsulinemia would cause hypokalemia, not hyperkalemia. * **D. Hyperaldosteronism:** Aldosterone promotes potassium excretion in the distal tubule [1]. CKD patients often suffer from **Hypoaldosteronism** (specifically Type 4 Renal Tubular Acidosis), which exacerbates hyperkalemia [4]. **NEET-PG High-Yield Pearls:** * **ECG Changes:** The earliest sign of hyperkalemia is **tall, peaked T-waves**. As levels rise, look for PR prolongation, loss of P-waves, and the classic "Sine wave" pattern. * **Treatment:** Calcium gluconate is the first-line treatment to **stabilize the cardiac membrane**, but it does not lower potassium levels [4]. * **Medication Alert:** ACE inhibitors and ARBs, commonly used in CKD for proteinuria, can worsen hyperkalemia by inhibiting the Renin-Angiotensin-Aldosterone System (RAAS) [1].

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: Gitelman's Syndrome differs from Bartter's Syndrome in all except:

Less common. **Explanation:** The correct answer is **A (Less common)** because Gitelman’s Syndrome is actually **more common** than Bartter’s Syndrome. While both are autosomal recessive salt-wasting tubulopathies, Gitelman’s has a higher prevalence (approximately 1 in 40,000) compared to Bartter’s (1 in 100,000). **Why the other options are incorrect (Features of Gitelman’s):** * **B. Later age of presentation:** Bartter’s often presents in utero (polyhydramnios) or infancy with growth retardation. Gitelman’s typically presents in late childhood or adulthood. * **C. Prominent neuromuscular signs:** Due to profound **hypomagnesemia**, Gitelman’s patients frequently suffer from fatigue, muscle cramps, and tetany, which are less prominent in Bartter’s. * **D. Generally milder clinical course:** Bartter’s is often severe with significant volume depletion and growth failure. Gitelman’s is usually more indolent, though it can impact quality of life through chronic fatigue. **High-Yield NEET-PG Pearls:** 1. **Site of Defect:** Bartter’s affects the **Thick Ascending Limb (TAL)** (mimics Loop diuretics); Gitelman’s affects the **Distal Convoluted Tubule (DCT)** (mimics Thiazide diuretics). 2. **Urinary Calcium:** This is the key differentiator. Bartter’s presents with **Hypercalciuria** (risk of nephrocalcinosis), whereas Gitelman’s presents with **Hypocalciuria**. 3. **Magnesium:** Hypomagnesemia is a hallmark and much more severe in Gitelman's syndrome. 4. **Commonality:** Both present with Metabolic Alkalosis, Hypokalemia, and Normal/Low Blood Pressure.

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: Presence of which of the following in the urine is diagnostic of glomerular injury?

20% dysmorphic RBCs. The presence of **dysmorphic Red Blood Cells (RBCs)** in the urine is a hallmark of **glomerular bleeding** [1]. When RBCs pass through the damaged glomerular basement membrane (GBM) and travel through the varying osmotic gradients of the renal tubules, they undergo mechanical and chemical stress. This results in distorted shapes, such as blebs, protrusions, or fragmented membranes [1]. * **Why Option B is correct:** While various thresholds exist, the presence of **>20% dysmorphic RBCs** (or specifically **>5% Acanthocytes/G1 cells**) is highly specific for a glomerular source of hematuria (e.g., Glomerulonephritis). Acanthocytes, which are ring-shaped RBCs with vesicle-like protrusions, are the most reliable markers [1]. * **Why Option A is incorrect:** Bright red cells (isomorphic RBCs) usually indicate **non-glomerular bleeding** from the lower urinary tract (ureters, bladder, or urethra), such as from stones, trauma, or malignancy [1]. * **Why Option C is incorrect:** The quantity of RBCs (100 RBCs/HPF) indicates the severity of hematuria but does not localize the site of injury. Both glomerular and post-glomerular pathologies can cause high-grade hematuria [1]. * **Why Option D is incorrect:** Beta-2 microglobulin is a low-molecular-weight protein. Increased levels in the urine are a marker of **tubular injury** (proximal tubule dysfunction), not glomerular injury. **High-Yield Clinical Pearls for NEET-PG:** * **Red Cell Casts:** These are 100% pathognomonic for glomerular hematuria [1]. * **Acanthocytes:** Specifically, the "Mickey Mouse" appearance of RBCs is the most specific type of dysmorphic cell for glomerulonephritis. * **Glomerular vs. Non-Glomerular:** Glomerular hematuria is often associated with significant proteinuria (>500 mg/day) and a "smoky" or "cola-colored" urine appearance, whereas non-glomerular hematuria often presents with blood clots [1].

Question 1

What is the cause of hyperkalemia in chronic kidney failure?

Accepted Answer

Decreased excretion

Answer

Release from cells

Answer

Hyperinsulinemia

Answer

Hyperaldosteronism

Question 2

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

Accepted Answer

20

Answer

40

Answer

20-30

Answer

30-40

Question 3

Gitelman's Syndrome differs from Bartter's Syndrome in all except:

Accepted Answer

Less common

Answer

Later age of presentation

Answer

Prominent neuromuscular signs and symptoms

Answer

Generally milder clinical course

Question 4

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 5

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 6

Which is the most common cause of this condition?

Accepted Answer

Diabetes

Answer

Berger Disease

Answer

Aortic Embolism

Answer

Dissection of aorta

Question 7

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 8

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 9

Presence of which of the following in the urine is diagnostic of glomerular injury?

Accepted Answer

20% dysmorphic RBCs

Answer

Bright red cells

Answer

100 RBCs per high power field

Answer

Beta-2 microglobulin

Question 10

Which of the following conditions is typically associated with hyperphosphatemia?

Accepted Answer

Chronic renal failure

Answer

Rickets

Answer

Prolonged phosphate intake

Answer

Osteitis fibrosa cystica

Nephrology — MCQs

Nephrology — MCQs

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