Nephrology — MCQs

Nephrology Indian Medical PG Practice Questions and MCQs

Question 851: Which of the following is not a contraindication for renal biopsy?

A. Bleeding diathesis
B. CRF with normal kidney (Correct Answer)
C. 60 % damage of kidney texture
D. Uncontrolled hypertension

Explanation: ***CRF with normal kidney*** - This is **not a contraindication** because chronic renal failure (CRF) with a normal-sized kidney often indicates a potentially **reversible or treatable** underlying kidney disease, making biopsy valuable for diagnosis and guiding treatment. [1] - A biopsy could help determine the specific cause of CRF, such as certain **glomerulonephropathies**, that might respond to targeted therapies. [1] *Bleeding diathesis* - A **bleeding diathesis**, such as severe **thrombocytopenia** or significant coagulopathy, significantly increases the risk of **hemorrhage** during and after a percutaneous renal biopsy. - This condition makes procedures that involve tissue penetration particularly hazardous due to uncontrolled bleeding. *60 % damage of kidney texture* - **Extensive kidney damage** (e.g., 60% damage or severely atrophic kidneys) often indicates **advanced, irreversible fibrosis**, where a biopsy is unlikely to provide therapeutically actionable information. [1] - The procedure carries risks, and if the kidney is severely compromised, the diagnostic yield is low, while the risk of complications (e.g., bleeding, infection) remains. *Uncontrolled hypertension* - **Uncontrolled hypertension** poses a significant risk for complications, particularly **post-biopsy bleeding** and **hematoma formation**, due to increased intravascular pressure. [1] - Blood pressure should be adequately controlled (e.g., below 140/90 mmHg) before performing a renal biopsy to minimize these vascular risks.

Question 852: Which of the following statements is most accurate regarding adult polycystic kidney disease (APKD)?

A. M/C cause of death is cardiovascular
B. Autosomal dominant inheritance. (Correct Answer)
C. PCKD associated with PKD2 gene is severe.
D. Cysts can convert to cancer.

Explanation: ***Autosomal dominant inheritance.*** - **Autosomal dominant polycystic kidney disease (ADPKD)** is the most common form, meaning only one copy of the mutated gene from one parent is sufficient to cause the disease [1]. - This inheritance pattern leads to a 50% chance of transmission to each child, which is characteristic of the adult form. *M/C cause of death is cardiovascular* - While **cardiovascular complications**, particularly **hypertension** and **heart failure**, are very common in ADPKD and contribute significantly to morbidity, the leading cause of death is **renal failure** requiring dialysis or transplantation [1]. - Many patients die from complications related to **end-stage renal disease (ESRD)**, such as **uremia** or complications from renal replacement therapy [1]. *Cysts can convert to cancer.* - While there is a slightly increased risk of **renal cell carcinoma** in ADPKD patients, the **cysts themselves do not typically transform into cancer**. - The malignancy usually arises from the normal kidney parenchyma between the cysts, not from malignant degeneration of the cyst lining. *PCKD associated with PKD2 gene is severe.* - Mutations in the **PKD2 gene** are generally associated with a **milder clinical course** and a later onset of end-stage renal disease (ESRD) compared to mutations in the **PKD1 gene** [1]. - Patients with **PKD1 mutations** typically experience a more severe disease, with a faster decline in renal function and earlier development of ESRD [1].

Question 853: What is the primary cause of edema in nephritic syndrome?

A. Decreased plasma protein concentration
B. Reduced plasma osmotic pressure
C. Increased plasma protein concentration
D. Sodium and water retention (Correct Answer)

Explanation: ***Sodium and water retention*** - In nephritic syndrome, **sodium and water retention** occurs due to kidney inflammation, leading to fluid overload [1]. - This results in increased **blood volume**, causing edema as a key clinical feature [1]. *Increased in plasma protein concentration* - Nephritic syndrome typically leads to **decreased**, not increased, plasma protein levels due to proteinuria. - Higher plasma protein levels would not contribute to edema; in fact, they would do the opposite by promoting osmotic balance. *Reduced plasma osmotic pressure* - While reduced osmotic pressure contributes to edema, in nephritic syndrome, the main factor is sodium and water retention [1]. - This oes not accurately describe the underlying cause in nephritic syndrome. *Decreased in plasma protein concentration* - Although nephritic syndrome may involve decreased protein concentration, edema is primarily due to **fluid retention** [1]. - Directly stating decreased plasma proteins oversimplifies the dynamic fluid balance that is disrupted in nephritic syndrome.

Question 854: At what glomerular filtration rate (GFR) is the term "end-stage renal disease (ESRD)" typically classified?

A. less than 15% of normal (Correct Answer)
B. 10%—25% of normal
C. 15%—25% of normal
D. 5%—10% of normal

Explanation: ***Less than 15% of normal*** - **End-stage renal disease (ESRD)** is defined by a **glomerular filtration rate (GFR)** that falls below **15 mL/min/1.73 m²**, which is approximately **less than 15% of normal function**. - At this stage, **renal replacement therapy** (dialysis or transplantation) is typically required to sustain life. *15%—25% of normal* - This GFR range (15-25 mL/min/1.73 m²) corresponds to **Stage 4 chronic kidney disease (CKD)**, which is severe but not yet formally "end-stage." - Patients in this stage require careful monitoring and management, but may not immediately need renal replacement therapy. *10%—25% of normal* - This range overlaps with both **severe CKD (Stage 4)** and the beginning of **ESRD (Stage 5)**, but it is not the precise definition for ESRD. - The critical threshold for ESRD is uniformly established as GFR below 15 mL/min/1.73 m². *5%—10% of normal* - While a GFR in this range certainly indicates **ESRD**, the official classification includes any GFR **below 15% of normal** (or below 15 mL/min/1.73 m²), making "less than 15%" the most accurate and inclusive answer. - This smaller range describes a more advanced state within ESRD, but not the general definition.

Question 855: Increased anion gap metabolic acidosis is associated with all of the following conditions except:

A. Starvation
B. Diarrhoea (Correct Answer)
C. Lactic acidosis
D. Salicylate poisoning

Explanation: ***Diarrhoea*** - Diarrhoea causes **non-anion gap metabolic acidosis** due to the loss of **bicarbonate-rich fluids** from the gastrointestinal tract [3]. - The anion gap remains normal because **chloride levels increase** to compensate for the bicarbonate loss, maintaining electroneutrality. *Starvation* - Prolonged starvation leads to **ketoacidosis** as the body breaks down fats for energy, producing **ketone bodies** (acetoacetate, beta-hydroxybutyrate) [1]. - These unmeasured anions increase the **anion gap**. *Salicylate poisoning* - Salicylate poisoning causes an **increased anion gap metabolic acidosis** because salicylates are organic acids and interfere with cellular metabolism [2]. - It often presents as a **mixed acid-base disorder** with an initial respiratory alkalosis due to central respiratory stimulation [2]. *Lactic acidosis* - Lactic acidosis results from the accumulation of **lactic acid**, an unmeasured anion, due to increased anaerobic metabolism (e.g., in shock or severe hypoxia) [2]. - This directly contributes to an **increased anion gap**.

Question 856: Which of the following is NOT a characteristic of Dent's disease?

A. Chloride channel defect
B. Defect in limb of Loop of Henle (Correct Answer)
C. Males are affected
D. Nephrolithiasis

Explanation: ***Defect in limb of Loop of Henle*** - Dent's disease is primarily a disorder affecting the **proximal renal tubule**, not the loop of Henle. - It is caused by mutations in the **CLC5 gene**, encoding a chloride channel, or in the OCRL1 gene. *Chloride channel defect* - Dent's disease is an X-linked recessive disorder caused by mutations in the **CLC5 gene**, which encodes a **chloride channel** located in the endosomes of the renal proximal tubule. - This channel's dysfunction leads to impaired protein reabsorption and other tubular defects. *Males are affected* - Dent's disease is an **X-linked recessive disorder**, meaning it predominantly affects males. - Females are typically carriers and are usually asymptomatic or have much milder symptoms due to random X-chromosome inactivation. *Nephrolithiasis* - Patients with Dent's disease frequently develop **nephrolithiasis (kidney stones)** due to hypercalciuria and hyperphosphaturia. - This is a common and often debilitating complication of the disease, contributing to progressive renal damage.

Question 857: What is the most common type of stone found in the bladder?

A. Ammonium urate
B. Struvite
C. Uric acid
D. Calcium oxalate (Correct Answer)

Explanation: ***Calcium oxalate*** - **Calcium oxalate** is the most common type of urinary stone overall, accounting for up to 80% of all stones, and is consequently the most frequent type found in the bladder. - The formation of **calcium oxalate stones** in the bladder is often associated with conditions causing stasis or high calcium excretion, although they can also form in the kidneys and descend [1]. *Ammonium urate* - **Ammonium urate stones** are relatively rare in developed countries but are more common in regions with endemic bladder stones, often linked to chronic urinary tract infections [1]. - These stones are typically soft, friable, and radiolucent, and are often a component of mixed stones. *Uric acid* - **Uric acid stones** are more common in patients with gout, metabolic syndrome, or conditions leading to persistently acidic urine, and are usually radiolucent [1]. - While they can occur in the bladder, they are not as prevalent as calcium oxalate stones in this location. *Struvite* - **Struvite stones** (magnesium ammonium phosphate) are strongly associated with **urinary tract infections** caused by **urea-splitting bacteria** (e.g., *Proteus* spp.) [1]. - They tend to grow rapidly and can form large, staghorn calculi, but are not the most common type of bladder stone overall [1].

Question 858: A patient presents with acute renal failure and a normal ultrasound abdomen report. What is the next most useful investigation?

A. Intravenous pyelography (IVP)
B. DTPA scan (Correct Answer)
C. CT scan for renal evaluation
D. Retrograde pyelography (RGP)

Explanation: ***DTPA scan*** - A **DTPA (diethylenetriamine pentaacetate) scan** assesses **renal perfusion** and **glomerular filtration rate (GFR)**, which is crucial for evaluating functional impairment in acute renal failure [1]. - Since the ultrasound is normal, ruling out structural obstruction [2], the next step is to evaluate the kidneys' functional status, and the DTPA scan is excellent for this. *Intravenous pyelography (IVP)* - **IVP** uses **iodinated contrast**, which is potentially **nephrotoxic** and should be avoided in patients with acute renal failure [3]. - It primarily evaluates the **collecting system** and **ureters** for structural abnormalities, which were already deemed normal by the ultrasound in this case. *Retrograde pyelography (RGP)* - **RGP** is an **invasive procedure** involving the retrograde injection of contrast into the ureters and renal pelvis. - While it can visualize the upper urinary tract, it is typically reserved for cases where **obstruction is suspected** after less invasive methods or when definitive delineation of an obstruction is required, which is not indicated here given the normal ultrasound. *CT scan for renal evaluation* - A **CT scan for renal evaluation** often involves **contrast administration**, posing a risk of **contrast-induced nephropathy** in acute renal failure [3]. - While it provides detailed anatomical information, the initial ultrasound has already ruled out significant structural abnormalities, and a functional assessment is now more critical.

Question 859: Which of the following statements about acute tubular necrosis (ATN) is false?

A. Urine sodium < 20mmol/l is true for ATN.
B. Blood urea: creatinine ratio < 20 is true for ATN.
C. Specific gravity of urine < 1.020 is true for ATN. (Correct Answer)
D. Urine Osmolality > 500 is true for ATN.

Explanation: ***Specific gravity of urine < 1.020 is true for ATN.*** * This statement is false because a urine **specific gravity < 1.020** indicates **dilute urine**, which is characteristic of ATN due to the kidney's impaired concentrating ability. The question asks for the false statement, making this option the correct choice as it states a fact about ATN as being true. * In ATN, the damaged tubules cannot reabsorb water effectively, leading to fixed osmolality and low specific gravity, usually around **1.010 to 1.012**. *Urine sodium < 20mmol/l is true for ATN.* * This statement is false in the context of ATN; in ATN, the damaged tubules lose the ability to reabsorb sodium, leading to **increased urinary sodium concentration**, typically **> 20 mmol/L**. * Low urine sodium (< 20 mmol/L) is characteristic of **pre-renal azotemia**, where the kidneys are attempting to conserve sodium due to hypoperfusion [1]. *Blood urea: creatinine ratio < 20 is true for ATN.* * This statement is false in the context of ATN; in ATN, both urea and creatinine excretion are impaired, but the **reabsorption of urea is less efficient** than in prerenal states, leading to a blood urea:creatinine ratio that is typically **< 20:1** [1]. * A ratio **> 20:1** is typically seen in **pre-renal azotemia**, where there is disproportionate reabsorption of urea relative to creatinine [1]. *Urine Osmolality > 500 is true for ATN.* * This statement is false in the context of ATN; in ATN, the damaged renal tubules cannot concentrate urine, resulting in a **low urine osmolality**, typically **< 350 mOsm/kg** (often similar to plasma osmolality). * A urine osmolality **> 500 mOsm/kg** is characteristic of **pre-renal azotemia**, indicating intact tubular function striving to conserve water [1].

Question 860: Which of the following causes polyuria?

A. Rhabdomyolysis
B. Interstitial nephritis
C. Hypokalemia
D. A.D.H insufficiency (Correct Answer)

Explanation: ***A.D.H insufficiency*** - **Antidiuretic hormone (ADH)**, also known as **vasopressin**, regulates water reabsorption in the kidneys. Insufficiency leads to impaired reabsorption, resulting in excessive water excretion and thus **polyuria**. - This condition is characteristic of **diabetes insipidus**, where the kidneys cannot concentrate urine, leading to the production of large volumes of dilute urine, which is a key symptom. *Interstitial nephritis* - This condition involves **inflammation of the renal interstitium** and tubules, often leading to **acute kidney injury (AKI)** or chronic kidney disease. - While it can impair renal concentrating ability in some cases, it is not the primary or most direct cause of profound polyuria compared to ADH insufficiency. *Hypokalemia* - Severe **hypokalemia** (low potassium levels) can cause **nephrogenic diabetes insipidus**, leading to polyuria due to impaired renal response to ADH. - However, **hypokalemia itself is not the direct cause of polyuria**; rather, it induces a state in the kidney that mimics ADH resistance. *Rhabdomyolysis* - This involves the **breakdown of muscle tissue**, releasing contents like myoglobin into the bloodstream, which can damage the kidneys and cause **acute kidney injury (AKI)**. - AKI associated with rhabdomyolysis typically presents with **oliguria** (low urine output) or **anuria** (no urine output) due to tubular necrosis and obstruction, rather than polyuria.

Practice by Chapter

Acute Kidney Injury

Practice Questions

Chronic Kidney Disease

Practice Questions

Glomerular Diseases

Practice Questions

Tubulointerstitial Diseases

Practice Questions

Nephrotic and Nephritic Syndromes

Practice Questions

Urinary Tract Infections

Practice Questions

Renal Replacement Therapy

Practice Questions

Fluid and Electrolyte Disorders

Practice Questions

Acid-Base Disorders

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Kidney in Systemic Diseases

Practice Questions

Kidney Stones and Obstructive Uropathy

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Hypertension in Kidney Disease

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Nephrology — MCQs

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