Nephrology Practice Questions

Q: Which type of renal stones is associated with laxative abuse?

Uric acid stones. ***Uric acid stones*** - Chronic laxative abuse can lead to **dehydration** and **diarrhea**, causing significant fluid and bicarbonate loss. This loss results in systemic metabolic acidosis and a persistently **acidic urine pH**. [1] - A persistently **acidic urine pH** (typically below 5.5) reduces the solubility of uric acid, promoting its crystallization and the formation of uric acid stones. [1] *Ammonium urate stones* - These stones are often seen in conditions with chronic **urinary tract infections** (UTIs) caused by **urea-splitting organisms** (e.g., Proteus), especially in children or in contexts of chronic diarrhea where ammonia production is increased. - While laxative abuse can cause diarrhea, it primarily leads to an acidic urine pH rather than the alkaline pH and high ammonia concentration typically associated with ammonium urate stones. *Struvite stones* - **Struvite stones** (magnesium ammonium phosphate) are predominantly associated with **urinary tract infections** by **urea-splitting organisms** (e.g., Proteus mirabilis) that elevate urinary pH and ammonia levels. [1] - Laxative abuse leads to an acidic urine pH, which is not conducive to struvite stone formation. *Calcium oxalate stones* - **Calcium oxalate stones** are the most common type of renal stone and are usually associated with hypercalciuria, hyperoxaluria, hypocitraturia, or low urine volume. - While dehydration from laxative abuse can increase urine concentration, the primary biochemical derangement leading to uric acid stones (acidic urine) is different from the risk factors for calcium oxalate stones.

Q: Which of the following is a cause of hypokalemic metabolic alkalosis with hypertension?

Liddle syndrome. ***Liddle syndrome*** - It is an **autosomal dominant** disorder characterized by a mutation in the **ENaC channel**, leading to increased sodium reabsorption and potassium excretion, thus causing **hypokalemia**, **metabolic alkalosis**, and **hypertension**. [1] - This condition mimics **primary hyperaldosteronism** but has **low plasma renin activity** and **low aldosterone levels**. [1] *Bartter syndrome* - This is a genetic disorder affecting the **Na-K-2Cl cotransporter** in the **thick ascending limb** of the loop of Henle, leading to **salt wasting** and compensatory **renin-angiotensin-aldosterone system activation**. - It presents with **hypokalemia**, **metabolic alkalosis**, but typically with **normal or low blood pressure**, not hypertension. *Gitelman syndrome* - This is an autosomal recessive disorder affecting the **thiazide-sensitive Na-Cl cotransporter** in the **distal convoluted tubule**. - It causes **hypokalemic metabolic alkalosis**, hypomagnesemia, and hypocalciuria, but patients are typically **normotensive** or **hypotensive**, distinguishing it from Liddle syndrome. *Renal tubular acidosis* - This is a group of disorders characterized by the **kidneys' inability to excrete acid** or **reabsorb bicarbonate**, leading to **metabolic acidosis**. [2] - While it can cause electrolyte abnormalities, hypokalemia is a feature of certain types (e.g., RTA type 1 and 2), but the defining feature is **metabolic acidosis**, not metabolic alkalosis, and it is not typically associated with hypertension from the primary tubular defect. [2]

Q: Most common acute complication of dialysis is

Hypotension. ***Hypotension*** - **Intradialytic hypotension** is the most common acute complication, occurring in 15-30% of dialysis sessions. - It is often caused by rapid removal of fluid (ultrafiltration), leading to a significant drop in blood pressure [1]. *Bleeding* - While bleeding can occur due to **anticoagulation** used during dialysis or as a complication of vascular access, it is less common than hypotension. - It is not considered the most frequent acute complication of the dialysis procedure itself. *Dementia* - **Dementia** is a chronic neurological condition that is not an acute complication directly attributable to a single dialysis session. - It can be a long-term comorbidity in patients with end-stage renal disease (ESRD), but not an immediate side effect. *Muscle cramps* - **Muscle cramps** are a relatively common acute complication during or immediately after dialysis, affecting about 5-20% of patients. - However, their frequency is generally lower than that of intradialytic hypotension [1].

Q: Crush Syndrome is associated with all of the following features except -

Hypercalcemia. ***Hypercalcemia*** - Crush syndrome involves massive **muscle damage** leading to the release of intracellular contents, but hypercalcemia is not typically seen acutely. - While skeletal muscle contains calcium, its release, if any, is usually outweighed by other electrolyte shifts and renal dysfunction, often leading to **hypocalcemia** due to calcium binding to damaged tissues and phosphate. *Hypocalcemia* - This is a common feature of **crush syndrome** because calcium ions move into damaged cells and bind to free fatty acids and damaged tissue. - The elevated **phosphate levels** released from damaged cells can also bind to circulating calcium, further reducing serum calcium. *Hyperkalemia* - One of the most dangerous complications of **crush syndrome**, resulting from the massive release of **intracellular potassium** from damaged muscle cells. - Can lead to **life-threatening arrhythmias** if not promptly managed. *Increased serum creatinine* - Damaged muscle releases large amounts of **creatinine**, which is a byproduct of muscle metabolism; this, along with **myoglobin** (leading to acute kidney injury), causes a significant increase in serum creatinine levels. - **Acute kidney injury** due to rhabdomyolysis is a hallmark of crush syndrome, leading to impaired clearance of waste products.

Q: Muehrcke lines in nails are seen in

Nephrotic syndrome. ***Nephrotic syndrome*** - **Muehrcke lines** are paired, white, transverse lines that do not move with nail growth, characteristic of **hypoalbuminemia** seen in nephrotic syndrome [1]. - These lines are caused by **edema** in the nail bed, making them visible through the nail plate. *Bartter syndrome* - Characterized by a defect in the **sodium-potassium-chloride cotransporter** in the loop of Henle, leading to electrolyte imbalances. - It does not typically present with nail changes like Muehrcke lines. *Nail-patella syndrome* - A genetic disorder causing **skeletal abnormalities**, including hypoplastic or absent patellae and nail dysplasia. - Nail changes are usually structural abnormalities (e.g., triangular lunulae, ridging), not Muehrcke lines. *Acute tubular necrosis* - Involves damage to the **renal tubules**, often causing acute kidney injury and electrolyte disturbances. - While it can lead to kidney dysfunction, it is not specifically associated with Muehrcke lines.

Q: Which of the following types of kidney stones are commonly associated with urinary tract infections?

Struvite stones. ***Struvite stones*** - **Struvite stones** (magnesium ammonium phosphate) are strongly associated with **urinary tract infections (UTIs)** caused by urease-producing bacteria like *Proteus* and *Klebsiella*. - These bacteria hydrolyze urea into ammonia and carbon dioxide, increasing urine pH and promoting the precipitation of struvite, often forming **staghorn calculi** [1]. *Cystine stones* - **Cystine stones** are caused by a **genetic defect** in amino acid transport, leading to increased excretion of cystine, ornithine, lysine, and arginine (COLA) in the urine. - They are not directly associated with UTIs but rather with a rare inherited metabolic disorder called **cystinuria**. *Xanthine stones* - **Xanthine stones** are very rare and typically occur in individuals with **xanthinuria**, a genetic disorder characterized by a deficiency in xanthine oxidase. - They are also not linked to UTIs but are a consequence of abnormal purine metabolism. *Calcium oxalate stones* - **Calcium oxalate stones** are the most common type of kidney stone, resulting from high levels of calcium and oxalate in the urine, often due to dietary factors, malabsorption, or idiopathic hypercalciuria. - While UTIs can complicate any kidney stone, **calcium oxalate stones** are not primarily *caused* by UTIs. [1]

Q: Polyuria with low fixed specific gravity urine is seen in ?

Chronic glomerulonephritis. ***Chronic glomerulonephritis*** - Damage to the **renal tubules** in chronic glomerulonephritis impairs their ability to concentrate urine, leading to polyuria with a **low, fixed specific gravity**. [1] - This fixed specific gravity reflects the kidneys' inability to adjust urine concentration in response to hydration status, a hallmark of **chronic kidney disease**. [2] *Diabetes mellitus* - Polyuria in diabetes mellitus is caused by **osmotic diuresis** due to high glucose levels in the urine, leading to increased urinary volume. [2] - While there is polyuria, the specific gravity is not necessarily fixed and can vary, often being high due to the presence of glucose. *Diabetes insipidus* - Diabetes insipidus causes polyuria and dilute urine due to either a deficiency of **ADH (central DI)** or renal unresponsiveness to ADH **(nephrogenic DI)**. - While it causes polyuria with low specific gravity, it's typically *not* fixed; the urine specific gravity can still fluctuate to some extent depending on the patient's hydration, or in response to ADH if it's central DI. *Potomania* - Potomania, or **primary polydipsia**, is excessive water intake that leads to dilutional hyponatremia and polyuria. - The kidneys are otherwise healthy and can still concentrate urine to some extent if water intake is restricted, preventing a truly fixed low specific gravity.

Q: Which of the following is the MOST common condition caused by hypernatremia?

Seizure. ***Seizure*** - While not the *most* common initial symptom, **seizure** can be a severe manifestation of hypernatremia, particularly when the serum sodium levels rise rapidly or to very high concentrations leading to significant neuronal dehydration. - **Rapid correction of severe hypernatremia** can also induce seizures if the brain cells swell too quickly. *Altered mental status* - **Altered mental status** such as lethargy, confusion, or irritability, is a very common and often an earlier symptom of hypernatremia due to neuronal dehydration and intracellular water shifts, but it generally precedes more severe neurological complications like seizures.[1] - It is a broad term that encompasses a range of neurological dysfunctions, and while frequent, it is not as specific a severe endpoint as a seizure. *Brain hemorrhage* - **Brain hemorrhage** is a rare and severe complication of hypernatremia, primarily seen when extreme osmotic shifts cause significant brain shrinkage, leading to tension on bridging veins and potential rupture. - This is not a common presentation and typically occurs only in very severe cases of hypernatremia or during overly rapid correction. *Central pontine myelinosis* - **Central pontine myelinolysis (CPM)** is a neurological disorder caused by too rapid correction of *chronic hyponatremia*, not hypernatremia.[1] - It results from osmotic damage to myelin sheaths in the pons, leading to severe neurological deficits such as dysphagia, dysarthria, and even locked-in syndrome.[1]

Q: Which of the following conditions is a direct indication for initiating dialysis?

Severe hyperkalemia. ### Severe hyperkalemia - **Severe hyperkalemia** (potassium levels typically >6.5 mEq/L or rapidly rising, especially with ECG changes) is an immediate life-threatening indication for dialysis when conservative measures fail or are insufficient [1]. - Dialysis effectively removes **excess potassium** from the blood, preventing fatal cardiac arrhythmias. *Severe metabolic acidosis* - While **severe metabolic acidosis** (pH <7.1-7.2) can be an indication, it is often managed first with bicarbonate administration and is typically not a stand-alone **direct** *emergency* indication for dialysis unless accompanied by other severe features or resistance to medical therapy. - The decision to dialyze for acidosis often depends on the underlying cause, degree of renal failure, and response to initial management [2]. *Fluid overload* - **Fluid overload** is a common complication of kidney failure, but it becomes a *direct* indication for dialysis when it is **refractory to diuretic therapy** and causes life-threatening symptoms such as **pulmonary edema** [2]. - Without such refractory state and immediate danger, fluid overload itself is not always an *immediate* trigger for dialysis compared to severe hyperkalemia. *Acute kidney injury* - **Acute kidney injury** (AKI) is the underlying *condition* that can lead to indications for dialysis, but AKI itself is not a *direct indication* for dialysis. - Dialysis is initiated for the *complications* of AKI, such as refractory hyperkalemia, severe metabolic acidosis, or fluid overload, rather than the diagnosis of AKI alone [2].

Q: Which of the following symptoms is least likely to be associated with hyponatremia?

Myalgia. Myalgia - While muscle cramps can occur with electrolyte imbalances, generalized myalgia (muscle pain) is not a typical or primary symptom of hyponatremia. - Hyponatremia primarily affects neurological function due to osmotic shifts in the brain. anorexia - Anorexia (loss of appetite) is a common, non-specific symptom of many metabolic disturbances, including hyponatremia, and often accompanies nausea and vomiting. - It arises from the general malaise and gastrointestinal upset associated with the condition. Convulsions - Convulsions are a severe neurological symptom of acute and profound hyponatremia, resulting from cerebral edema and increased intracranial pressure [1]. - This occurs when the brain swells due to the osmotic shift of water into brain cells. Drowsiness - Drowsiness is a frequent neurological manifestation of hyponatremia, indicative of altered mental status [1]. - It reflects impaired brain function due to the osmotic disturbances and potential cerebral edema [1].

Question 1

Which type of renal stones is associated with laxative abuse?

Accepted Answer

Uric acid stones

Answer

Struvite stones

Answer

Calcium oxalate stones

Answer

Ammonium urate stones

Question 2

Which of the following is a cause of hypokalemic metabolic alkalosis with hypertension?

Accepted Answer

Liddle syndrome

Answer

Bartter syndrome

Answer

Gitelman syndrome

Answer

Renal tubular acidosis

Question 3

Most common acute complication of dialysis is

Accepted Answer

Hypotension

Answer

Bleeding

Answer

Dementia

Answer

Muscle cramps

Question 4

Crush Syndrome is associated with all of the following features except -

Accepted Answer

Hypercalcemia

Answer

Hypocalcemia

Answer

Hyperkalemia

Answer

Increased serum creatinine

Question 5

Muehrcke lines in nails are seen in

Accepted Answer

Nephrotic syndrome

Answer

Bartter syndrome

Answer

Nail-patella syndrome

Answer

Acute tubular necrosis

Question 6

Which of the following types of kidney stones are commonly associated with urinary tract infections?

Accepted Answer

Struvite stones

Answer

Cystine stones

Answer

Xanthine stones

Answer

Calcium oxalate stones

Question 7

Polyuria with low fixed specific gravity urine is seen in ?

Accepted Answer

Chronic glomerulonephritis

Answer

Diabetes mellitus

Answer

Diabetes insipidus

Answer

Potomania

Question 8

Which of the following is the MOST common condition caused by hypernatremia?

Accepted Answer

Seizure

Answer

Altered mental status

Answer

Brain hemorrhage

Answer

Central pontine myelinosis

Question 9

Which of the following conditions is a direct indication for initiating dialysis?

Accepted Answer

Severe hyperkalemia

Answer

Severe metabolic acidosis

Answer

Fluid overload

Answer

Acute kidney injury

Question 10

Which of the following symptoms is least likely to be associated with hyponatremia?

Accepted Answer

Myalgia

Answer

anorexia

Answer

Drowsiness

Answer

Convulsions

Nephrology — MCQs

Nephrology — MCQs

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