Nephrology Practice Questions

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

CRF with normal kidney. ***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.

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

Autosomal dominant inheritance.. ***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].

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

less than 15% of normal. ***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.

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

Diarrhoea. ***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**.

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

Sodium and water retention. ***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.

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

DTPA scan. ***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.

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

Calcium oxalate. ***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].

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

Defect in limb of Loop of Henle. ***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.

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

Specific gravity of urine < 1.020 is true for ATN.. ***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 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 20:1** 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 ** 500 mOsm/kg** is characteristic of **pre-renal azotemia**, indicating intact tubular function striving to conserve water [1].

Q: Which of the following causes polyuria?

A.D.H insufficiency. ***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.

Question 1

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

Accepted Answer

CRF with normal kidney

Answer

Bleeding diathesis

Answer

60 % damage of kidney texture

Answer

Uncontrolled hypertension

Question 2

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

Accepted Answer

Autosomal dominant inheritance.

Answer

M/C cause of death is cardiovascular

Answer

PCKD associated with PKD2 gene is severe.

Answer

Cysts can convert to cancer.

Question 3

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

Accepted Answer

less than 15% of normal

Answer

10%—25% of normal

Answer

15%—25% of normal

Answer

5%—10% of normal

Question 4

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

Accepted Answer

Diarrhoea

Answer

Starvation

Answer

Lactic acidosis

Answer

Salicylate poisoning

Question 5

What is the primary cause of edema in nephritic syndrome?

Accepted Answer

Sodium and water retention

Answer

Decreased plasma protein concentration

Answer

Reduced plasma osmotic pressure

Answer

Increased plasma protein concentration

Question 6

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

Accepted Answer

DTPA scan

Answer

Intravenous pyelography (IVP)

Answer

CT scan for renal evaluation

Answer

Retrograde pyelography (RGP)

Question 7

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

Accepted Answer

Calcium oxalate

Answer

Ammonium urate

Answer

Struvite

Answer

Uric acid

Question 8

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

Accepted Answer

Defect in limb of Loop of Henle

Answer

Chloride channel defect

Answer

Males are affected

Answer

Nephrolithiasis

Question 9

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

Accepted Answer

Specific gravity of urine < 1.020 is true for ATN.

Answer

Urine sodium < 20mmol/l is true for ATN.

Answer

Blood urea: creatinine ratio < 20 is true for ATN.

Answer

Urine Osmolality > 500 is true for ATN.

Question 10

Which of the following causes polyuria?

Accepted Answer

A.D.H insufficiency

Answer

Rhabdomyolysis

Answer

Interstitial nephritis

Answer

Hypokalemia

Nephrology — MCQs

Nephrology — MCQs

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