Nephrology — MCQs
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Prerenal and renal azotemia are differentiated on the basis of.
Which of the following statements about autosomal dominant polycystic kidney disease (ADPKD) is incorrect?
Polycystic disease of the kidney may have cysts in all of the following organs except?
Mainstay of treatment of nephrogenic diabetes insipidus is:
A boy is suffering from acute pyelonephritis. The most specific urinary finding will be:
Hyperkalemia without ECG changes may be treated with all except one of the following medications:
A patient presents with acute renal failure (ARF) and complete anuria, with a normal ultrasound of the kidneys. Which investigation will provide the best initial information regarding renal function?
What is a common electrolyte disturbance seen in chronic renal failure?
Nephrology Indian Medical PG Practice Questions and MCQs
Question 881: Prerenal and renal azotemia are differentiated on the basis of.
- A. Creatinine clearance
- B. Serum creatinine level
- C. Sodium fraction excretion (Correct Answer)
- D. Urine bicarbonate level
Explanation: ***Sodium fraction excretion*** - **Fractional excretion of sodium (FENa)** is a key indicator for differentiating prerenal azotemia from intrinsic renal azotemia [2]. - In **prerenal azotemia**, the kidneys avidly reabsorb sodium to conserve volume, leading to a **low FENa (<1%)**. In contrast, **renal azotemia** (e.g., acute tubular necrosis) typically presents with a **high FENa (>2%)** due to impaired sodium reabsorption [2]. *Creatinine clearance* - **Creatinine clearance** is a measure of **glomerular filtration rate (GFR)**, which is reduced in both prerenal and renal azotemia [1], [3]. - It does not specifically differentiate between the underlying cause of the reduced GFR (i.e., whether it's due to hypoperfusion or intrinsic kidney damage). *Serum creatinine level* - An **elevated serum creatinine level** is present in both prerenal and renal azotemia, indicating **renal dysfunction** [1]. - This measurement alone cannot distinguish whether the kidney injury is due to decreased perfusion or damage to the kidney itself. *Urine bicarbonate level* - **Urine bicarbonate levels** are primarily relevant in the assessment of **renal tubular acidosis** or other acid-base disorders. - They do not play a direct role in differentiating between prerenal and renal causes of azotemia.
Question 882: Which of the following statements about autosomal dominant polycystic kidney disease (ADPKD) is incorrect?
- A. Low Renin due to pressure atrophy of JG apparatus is a common finding in ADPKD. (Correct Answer)
- B. Spider leg deformity
- C. Anemia
- D. Cysts increase in size with age
Explanation: ***Low Renin due to pressure atrophy of JG apparatus is a common finding in ADPKD.*** - This statement is incorrect because **ADPKD** is typically associated with **elevated renin levels**. The enlarging cysts can cause **ischemia** and **stretch** of renal tissue, leading to activation of the **renin-angiotensin-aldosterone system (RAAS)**. - The activation of RAAS, and consequently high renin, contributes to **hypertension**, a common complication in ADPKD. Pressure atrophy of the juxtaglomerular (JG) apparatus leading to low renin is not a characteristic feature. *Spider leg deformity* - This term refers to the characteristic appearance of the calyces on an **intravenous pyelogram (IVP)** in ADPKD. The presence of large cysts distorts the renal collecting system, giving rise to this radiographic sign. - While IVP is less commonly used today due to the widespread availability of CT and MRI, the **"spider leg" appearance** accurately describes the effect of multiple cysts on the renal pelvis and calyces. *Anemia* - **Anemia** is typically **less common** in ADPKD patients compared to other forms of chronic kidney disease (CKD) at similar stages. - This is because the large cystic kidneys may retain a relatively preserved capacity for **erythropoietin production**, which helps prevent severe anemia, unlike the fibrosis often seen in other CKDs. *Cysts increase in size with age* - The hallmark of ADPKD is the progressive growth and increase in number of renal cysts over time. This **cyst enlargement** leads to a gradual decline in renal function. - The age-related increase in cyst size and number contributes to the progressive nature of the disease, eventually leading to **end-stage renal disease (ESRD)** in many affected individuals.
Question 883: Polycystic disease of the kidney may have cysts in all of the following organs except?
- A. Lung (Correct Answer)
- B. Liver
- C. Pancreas
- D. Spleen
Explanation: ***Lung*** - While Polycystic Kidney Disease (PKD) is a **systemic disorder**, cysts are exceptionally rare or not typically found in the **lungs**. - PKD primarily affects organs that develop from common embryonic pathways, such as the kidney, liver, pancreas, and spleen. *Liver* - **Hepatic cysts** are the most common extrarenal manifestation of **autosomal dominant polycystic kidney disease (ADPKD)**, occurring in a majority of patients [1]. - These cysts can range from asymptomatic to causing significant hepatomegaly, pain, and liver dysfunction. *Pancreas* - **Pancreatic cysts** are another common finding in ADPKD, though generally **smaller and less clinically significant** than hepatic cysts. - They are usually asymptomatic but can sometimes lead to pancreatitis or pain. *Spleen* - **Splenic cysts** are a recognised but **less common** extrarenal manifestation in patients with ADPKD. - Like other extrarenal cysts, they are often asymptomatic and discovered incidentally.
Question 884: Mainstay of treatment of nephrogenic diabetes insipidus is:
- A. Thiazide / Amiloride diuretics and salt restriction (Correct Answer)
- B. Vasopressin and salt restriction
- C. Desmopressin
- D. Desmopressin with salt restriction
Explanation: ***Thiazide / Amiloride diuretics and salt restriction*** - **Thiazide diuretics** (e.g., hydrochlorothiazide) are the mainstay in nephrogenic diabetes insipidus by causing mild **volume depletion**, which enhances proximal tubular reabsorption of water and solutes, reducing urine volume. [1] - **Salt restriction** further supports this mechanism by helping to decrease filtered sodium load and consequently reducing water excretion. [1] *Desmopressin* - **Desmopressin** is a synthetic analog of **vasopressin** and is the primary treatment for **central diabetes insipidus**, where there is insufficient ADH production. [2] - In **nephrogenic diabetes insipidus**, the kidneys are resistant to ADH, so desmopressin would be ineffective. [2] *Vasopressin and salt restriction* - **Vasopressin** (arginine vasopressin, AVP) is the natural antidiuretic hormone whose action is impaired in nephrogenic diabetes insipidus due to **renal resistance**, making its administration ineffective. [2] - While salt restriction is beneficial, combining it with ineffective vasopressin would not be the mainstay of treatment. *Desmopressin with salt restriction* - As mentioned, **desmopressin** is ineffective in **nephrogenic diabetes insipidus** because the renal tubules are unresponsive to its action. [2] - Although **salt restriction** is a useful adjunct, its combination with an ineffective drug does not make it the mainstay of treatment for this specific condition.
Question 885: A boy is suffering from acute pyelonephritis. The most specific urinary finding will be:
- A. Bacteria in gram stain
- B. W.B.C. casts (Correct Answer)
- C. Leucocyte esterase test
- D. Nitrite test
Explanation: ***W.B.C. casts*** - **WBC casts** are pathognomonic for **pyelonephritis** as they indicate inflammation and infection within the **renal tubules**. - They form when white blood cells aggregate in the **tubular lumen** and are encased in **Tamm-Horsfall protein**, reflecting their renal origin. *Leucocyte esterase test* - The **leukocyte esterase test** detects the presence of enzymes released by **neutrophils**, indicating pyuria (white blood cells in urine). - While positive in pyelonephritis, it is not specific to the kidney and can be positive in **lower urinary tract infections** as well. *Nitrite test* - A **nitrite test** detects the presence of **nitrites**, which are formed by gram-negative bacteria that convert urinary nitrates. - This test is indicative of a bacterial infection but is not specific to the **upper urinary tract** (pyelonephritis) versus a **lower urinary tract infection** (cystitis). *Bacteria in gram stain* - The presence of **bacteria** on a Gram stain of unspun urine indicates a significant bacterial presence, often associated with a urinary tract infection. - However, it does not differentiate between **upper** (pyelonephritis) and **lower** (cystitis) urinary tract infections and is therefore not specific for pyelonephritis.
Question 886: Hyperkalemia without ECG changes may be treated with all except one of the following medications:
- A. Atenolol (Correct Answer)
- B. Na bicarbonate
- C. Insulin with dextrose
- D. Calcium gluconate
Explanation: ***Atenolol*** - **Atenolol** is a beta-blocker that does not play a direct role in the acute management of hyperkalemia. In fact, beta-blockers can sometimes **worsen hyperkalemia** by impairing cellular potassium uptake [3]. - Its primary use is for conditions like hypertension or angina, and it has no mechanism to significantly lower serum potassium levels or stabilize cardiac membranes in hyperkalemia. *Calcium gluconate* - **Calcium gluconate** is used to stabilize the cardiac membrane and prevent arrhythmias in hyperkalemia, particularly when ECG changes are present [1]. - While it doesn't lower serum potassium levels directly, it is crucial for **cardioprotection**, and its absence here implies the question is about potassium-lowering agents. *Na bicarbonate* - **Sodium bicarbonate** can be used to shift potassium intracellularly, particularly in patients with **metabolic acidosis**. - It increases intracellular pH, which promotes the movement of potassium into cells, thus lowering extracellular potassium. *Insulin with dextrose* - **Insulin with dextrose** is a common and effective treatment for hyperkalemia, as insulin promotes the uptake of potassium into cells. - Dextrose is administered concurrently to prevent **hypoglycemia**, which would otherwise occur due to the insulin [2].
Question 887: A patient presents with acute renal failure (ARF) and complete anuria, with a normal ultrasound of the kidneys. Which investigation will provide the best initial information regarding renal function?
- A. Serum Creatinine
- B. Urine Output Assessment
- C. Renal Biopsy
- D. DTPA Scan (Radiorenogram) (Correct Answer)
Explanation: DTPA Scan (Radiorenogram) - A DTPA scan can assess renal perfusion and glomerular filtration rate (GFR), providing crucial information about the functional status of the kidneys, particularly in cases of anuria [1]. - In the context of anuria with a normal ultrasound, it helps differentiate between pre-renal (poor perfusion), post-renal (if obstruction was missed), or intrinsic renal failure by evaluating blood flow and tracer uptake [1]. Serum Creatinine - While serum creatinine is a marker of renal function, it reflects the current state and doesn't provide real-time or dynamic information about renal blood flow or GFR at the onset of anuria [2]. - In acute renal failure, particularly with anuria, creatinine levels can rise rapidly, but assessing the cause and degree of functional impairment beyond simple filtration requires more advanced imaging. Urine Output Assessment - The patient is already presenting with complete anuria, meaning there is no urine output, rendering this assessment uninformative for further diagnostic steps. - While typically a crucial initial indicator, in this specific scenario, it only confirms the clinical presentation and does not provide insight into the underlying etiology of the anuria. Renal Biopsy - A renal biopsy is an invasive procedure primarily used for definitive diagnosis of intrinsic renal diseases and is not a first-line investigation for immediate assessment of renal function in acute anuria [2]. - It would typically be considered after non-invasive tests have failed to provide a diagnosis or if a specific intrinsic renal disease is strongly suspected and requires histological confirmation [2].
Question 888: What is a common electrolyte disturbance seen in chronic renal failure?
- A. Hyperkalemia (Correct Answer)
- B. Hypocalcemia
- C. Hypercalcemia
- D. Hyperphosphatemia
Explanation: **Hyperkalemia** - As **glomerular filtration rate (GFR)** decreases in chronic renal failure, the kidneys' ability to excrete potassium is significantly impaired, leading to its accumulation [1]. - This is a common and potentially life-threatening complication due to its effects on **cardiac rhythm** [1]. *Hypercalcemia* - While possible in some renal conditions, **hypercalcemia** is not a typical electrolyte disturbance seen primarily due to the loss of kidney function; instead, **hypocalcemia** is more characteristic [2]. - Renal failure often leads to impaired vitamin D activation and phosphate retention, which tend to lower, not raise, serum calcium [2]. *Hypocalcemia* - Although **hypocalcemia** is also a common feature of chronic renal failure, the question asks for "a common electrolyte disturbance" and **hyperkalemia** is often considered more immediately life-threatening and directly linked to impaired excretion. - It results from decreased production of **1,25-dihydroxyvitamin D** by the kidneys and phosphate retention, which binds to calcium [2]. *Hyperphosphatemia* - **Hyperphosphatemia** is indeed a very common electrolyte disturbance in chronic renal failure, resulting from the kidney's inability to excrete phosphate [2]. - However, the options present multiple common disturbances, and **hyperkalemia** is often highlighted due to its acute danger.
Practice by Chapter
Acute Kidney Injury
Practice Questions
Chronic Kidney Disease
Practice Questions
Glomerular Diseases
Practice Questions
Tubulointerstitial Diseases
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Nephrotic and Nephritic Syndromes
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Urinary Tract Infections
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Renal Replacement Therapy
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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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