Nephrology — MCQs

A 63-year-old man is in stable condition after an acute myocardial infarction when he becomes hypotensive for 3 hours before paramedical personnel arrive. Over the next week, the serum urea nitrogen level increases to 48 mg/dL, the serum creatinine level increases to 5 mg/dL, and the urine output decreases. He undergoes hemodialysis for the next 2 weeks and then develops marked polyuria, with a urine output of 2 to 3 L/day. His renal function gradually returns to normal. Which of the following substances is most likely released and participated in the elevation of BUN, creatinine, and reduced urinary output?

Q839

Which of the following causes hyperchloremic acidosis?

Q840

Positive urinary anion gap is found in which of the following conditions?

Nephrology Indian Medical PG Practice Questions and MCQs

Question 831: Pyuria is found in all except

A. Renal tuberculosis
B. Vaginosis
C. CA bladder
D. Appendicular abscess (Correct Answer)

Explanation: ***Appendicular abscess*** - An appendicular abscess is an **extraluminal collection of pus** originating from a ruptured appendix, usually contained within the peritoneum. - While it causes significant inflammation, it does not typically lead to **pyuria** because it is not directly associated with the urinary tract. *CA bladder* - **Carcinoma of the bladder** can lead to irritation and inflammation of the bladder lining. - This irritation can cause **hematuria** and, in some cases, an influx of white blood cells into the urine, resulting in **pyuria**. *Renal tuberculosis* - This is a form of **extrapulmonary tuberculosis** that affects the kidneys. - The infection directly within the renal parenchyma and urinary collecting system leads to significant **inflammation and pus formation**, causing **pyuria** [1]. *Vaginosis* - **Bacterial vaginosis** is an infection of the vagina [1]. - Due to the close anatomical proximity of the vagina and urethra, vaginal inflammation and discharge can result in **contamination of a urine sample** with white blood cells from the vagina, misinterpreted as pyuria [1].

Question 832: Most common presentation of renal cell carcinoma is

A. Abdominal mass
B. Hematuria (Correct Answer)
C. Flank pain
D. Nocturia

Explanation: ***Hematuria*** - **Hematuria** (blood in the urine) is the **most common presenting symptom** of renal cell carcinoma, occurring in about 60% of patients [1]. It is often **painless** [2] and can be gross or microscopic. - This symptom occurs due to the tumor eroding into the collecting system of the kidney, causing blood to mix with urine. *Abdominal mass* - While an **abdominal mass** can be a symptom of renal cell carcinoma [1], it is generally less common than hematuria as the initial presentation, occurring in about 45% of cases. - The mass is often **palpable** when the tumor has grown to a significant size [3], indicating a more advanced stage. *Flank pain* - **Flank pain** is another common symptom, but typically ranks third in frequency after hematuria and abdominal mass, presenting in about 40% of patients. - Pain usually arises when the tumor grows large enough to **compress surrounding structures** or invades the renal capsule. *Nocturia* - **Nocturia** (frequent urination at night) is **not a direct symptom** of renal cell carcinoma. - It is more commonly associated with benign conditions like **benign prostatic hyperplasia (BPH)**, urinary tract infections, or bladder overactivity.

Question 833: All of the following are decreased in nephrotic syndrome, except for:

A. Serum complement (C3)
B. Serum fibrinogen (Correct Answer)
C. Serum albumin
D. Serum transferrin

Explanation: ***Serum fibrinogen*** - **Fibrinogen** levels are generally **increased** in nephrotic syndrome due to compensatory hepatic synthesis triggered by the loss of other proteins and lipids, contributing to the hypercoagulable state. - The liver increases the production of various proteins, including clotting factors, in an attempt to maintain oncotic pressure, leading to elevated fibrinogen. *Serum transferrin* - **Transferrin** is a plasma protein responsible for iron transport and is significantly **decreased** in nephrotic syndrome due to its loss in the urine. - The urinary loss of transferrin can contribute to **iron-refractory microcytic anemia** seen in some nephrotic patients. *Serum albumin* - **Albumin** is the most abundant plasma protein and its severe **decrease** in nephrotic syndrome (hypoalbuminemia) is a hallmark of the condition due to massive urinary excretion [1]. - The low serum albumin is a primary cause of the characteristic **edema** in nephrotic syndrome due to reduced plasma oncotic pressure [2]. *Serum complement (C3)* - **Complement C3** levels are often **decreased** in nephrotic syndrome, particularly in glomerulonephritic causes like **post-streptococcal glomerulonephritis** or **membranoproliferative glomerulonephritis type 2**, where C3 is consumed [3]. - While not universally decreased in all nephrotic syndromes, significant urinary loss of C3 can occur, leading to reduced serum levels.

Question 834: In a case of autosomal dominant polycystic kidney disease, cysts are present in all of the following organs, except:

A. Pancreas
B. Seminal vesicles
C. Liver
D. Lung (Correct Answer)

Explanation: Cysts are generally not found in the lungs of patients with autosomal dominant polycystic kidney disease (ADPKD). - ADPKD primarily affects organs with epithelial linings derived from the mesonephric duct or related embryonic structures. ADPKD is a common autosomal dominant condition characterized by multiple renal cysts that enlarge over time, with mutations in PKD1 and PKD2 genes accounting for the majority of cases [1]. *Liver* - **Hepatic cysts** are the most common extrarenal manifestation of ADPKD, occurring in approximately 50-70% of patients. - Their prevalence and size tend to increase with age and female sex. *Pancreas* - **Pancreatic cysts** are also a recognized extrarenal manifestation of ADPKD, though less common than hepatic cysts. - They are typically asymptomatic but can occasionally cause symptoms. *Seminal vesicles* - **Seminal vesicle cysts** can occur in men with ADPKD, contributing to an increased risk of infertility or other reproductive issues. - They are often asymptomatic and found incidentally.

Question 835: What is the most likely diagnosis in a patient presenting with hypertension, proteinuria, and renal failure?

A. Mycosis fungoides
B. Wegener's granulomatosis (Correct Answer)
C. Invasive aspergillosis
D. Sarcoidosis

Explanation: ***Wegener's granulomatosis*** - This condition, now known as **Granulomatosis with Polyangiitis (GPA)**, classically presents as a triad of **upper respiratory tract disease**, **lower respiratory tract disease**, and **renal disease** [1]. - The renal involvement often manifests as **glomerulonephritis**, leading to **hypertension**, **proteinuria**, and potentially rapid progression to **renal failure** [2]. *Mycosis fungoides* - This is a **cutaneous T-cell lymphoma** primarily affecting the skin, presenting with patches, plaques, and tumors. - It typically does not involve the kidneys in a manner that would cause **hypertension**, **proteinuria**, and **renal failure**. *Invasive aspergillosis* - This is a serious **fungal infection** most commonly seen in **immunocompromised individuals**, affecting the lungs and other organs. - While it can cause systemic illness, it does not typically present with the classic triad of **hypertension**, **proteinuria**, and **renal failure** as a primary finding. *Sarcoidosis* - This is a **multisystem inflammatory disease** characterized by the formation of **non-caseating granulomas** in various organs, most commonly the lungs and lymph nodes. - While renal involvement can occur, it's less common and doesn't typically present with the acute, severe combination of **hypertension**, **proteinuria**, and **renal failure** seen in GPA.

Question 836: Renal biopsy is indicated in which of the following conditions?

A. Uncontrolled hypertension
B. Solitary kidney
C. Kidneys <60% predicted size
D. Nephrotic syndrome in adults (Correct Answer)

Explanation: ***Nephrotic syndrome in adults*** - A **renal biopsy** is indicated in adults with **nephrotic syndrome** to identify the underlying glomerular pathology and guide treatment decisions, as different causes (e.g., focal segmental glomerulosclerosis, membranous nephropathy) require specific therapies [1]. - While other imaging or blood tests may suggest a diagnosis, a biopsy provides a **definitive histological diagnosis** of the specific kidney disease [2]. *Uncontrolled hypertension* - **Uncontrolled hypertension** is usually managed medically, and a renal biopsy is typically not indicated unless there is suspicion of a **secondary cause of hypertension** directly affecting the kidneys (e.g., renovascular disease) that cannot be diagnosed by less invasive means. - Imaging studies like **renal artery Doppler** or CT angiography are usually the first line to investigate renal causes of hypertension, not biopsy [3]. *Solitary kidney* - A **solitary kidney** itself does not typically warrant a renal biopsy unless there is evidence of **acute renal injury**, **proteinuria**, or **hematuria** with no clear cause, and thus a need to investigate the underlying pathology. - The presence of a solitary kidney is a **contraindication to biopsy** if the other kidney is healthy, due to the increased risk of complications (e.g., bleeding, infection) in the only functioning kidney. *Kidneys <60% predicted size* - **Small kidney size** (less than 60% predicted) often indicates **chronic kidney disease** with established scarring or atrophy, where a biopsy may not provide actionable information beyond what is already known. - In such cases, if a biopsy is performed, it is usually to assess for specific, treatable causes of rapid progression in a small, atrophic kidney, but is not a routine indication for small kidneys alone due to difficulty obtaining adequate tissue and increased risk.

Question 837: Cause of nephrocalcinosis in granulomatous diseases is?

A. Dystrophic calcification
B. Mutation in calcium sensing receptor
C. Increased absorption
D. Increased conversion to 1,25 OH (Correct Answer)

Explanation: ***Increased absorption*** - Granulomatous diseases, like sarcoidosis, lead to increased **vitamin D** absorption, causing hypercalcemia and subsequently **nephrocalcinosis**. [4] - This mechanism results from the conversion of inactive vitamin D to its active form, increasing calcium mobilization from the gut. [3], [4] *Dystrophic calcification* - Refers to calcium deposition in **damaged tissues**, typically not related to the increased absorption of calcium in nephrocalcinosis. - It usually occurs in areas with preceding tissue necrosis, rather than the increased calcium absorption seen in granulomatous diseases. *Increased conversion to 1,25 OH* - Although **increased conversion** of vitamin D occurs, it is not the primary reason for nephrocalcinosis; rather, it's the secondary effect of **increased absorption** that leads to calcium overload. [3], [4] - The relationship is more about the resultant increased calcium levels causing kidney damage rather than a direct causative effect. *Mutation in calcium sensing receptor* - This mutation typically causes **primary hyperparathyroidism** or other calcium dysregulations, but it is unrelated to the mechanism of nephrocalcinosis in **granulomatous diseases**. [1], [2] - Granulomatous nephrocalcinosis is more about excess calcium due to absorption rather than receptor malfunctioning.

Question 838: A 63-year-old man is in stable condition after an acute myocardial infarction when he becomes hypotensive for 3 hours before paramedical personnel arrive. Over the next week, the serum urea nitrogen level increases to 48 mg/dL, the serum creatinine level increases to 5 mg/dL, and the urine output decreases. He undergoes hemodialysis for the next 2 weeks and then develops marked polyuria, with a urine output of 2 to 3 L/day. His renal function gradually returns to normal. Which of the following substances is most likely released and participated in the elevation of BUN, creatinine, and reduced urinary output?

A. Aldosterone (involved in fluid retention)
B. Endothelin (vasoconstrictor released in response to ischemia) (Correct Answer)
C. Natriuretic peptide (responds to heart failure)
D. Erythropoietin (stimulates red blood cell production)

Explanation: ***Endothelin (vasoconstrictor released in response to ischemia)*** - **Endothelin** is a potent **vasoconstrictor** released by endothelial cells in response to ischemia and injury, such as that caused by prolonged hypotension in the context of an acute myocardial infarction. Its effects lead to reduced renal blood flow. - Reduced renal blood flow causes **glomerular filtration rate (GFR) to decrease**, leading to the observed increase in **BUN** and **creatinine**, and reduced urine output (oliguria) due to acute kidney injury [2]. *Aldosterone (involved in fluid retention)* - **Aldosterone** is primarily involved in **sodium and water reabsorption** and potassium excretion, primarily by the distal tubules and collecting ducts. - While it contributes to fluid retention, it is not the primary mediator of the initial acute renal vasoconstriction and drop in GFR seen in ischemic acute kidney injury. *Natriuretic peptide (responds to heart failure)* - **Natriuretic peptides** (e.g., ANP, BNP) are released in response to **cardiac stretch** (e.g., in heart failure) and promote vasodilation and natriuresis (sodium excretion) [3]. - These effects would typically **increase GFR** and urine output, which is contrary to the reduced urine output and elevated BUN/creatinine observed in this case [3]. *Erythropoietin (stimulates red blood cell production)* - **Erythropoietin** is a hormone produced by the kidneys in response to **hypoxia**, stimulating red blood cell production in the bone marrow [1]. - It does not directly cause renal vasoconstriction or contribute to the acute rise in BUN and creatinine due to ischemia [1].

Question 839: Which of the following causes hyperchloremic acidosis?

A. Diarrhea leading to metabolic acidosis
B. Ileoplasty not affecting acid-base status
C. Ureterosigmoidostomy (Correct Answer)
D. Vomiting causing metabolic alkalosis

Explanation: ***Ureterosigmoidostomy*** - This procedure involves implanting ureters into the sigmoid colon, causing **urinary electrolytes** to be reabsorbed by the colon. - The colon reabsorbs **chloride** in exchange for **bicarbonate**, leading to **hyperchloremia** and **metabolic acidosis**. *Diarrhea leading to metabolic acidosis* - While diarrhea does cause **metabolic acidosis** due to bicarbonate loss, it is typically a **normochloremic** or anion-gap acidosis, not primarily hyperchloremic unless there are severe fluid losses or other complex factors. - The primary mechanism is loss of bicarbonate-rich fluid from the gastrointestinal tract, leading to a decrease in serum bicarbonate. *Ileoplasty not affecting acid-base status* - An **ileoplasty** (surgical reconstruction of the ileum) generally refers to procedures that do not inherently cause acid-base disturbances unless there are complications like obstruction or short bowel syndrome. - Unlike a ureterosigmoidostomy, the ileum is not typically used for urine draining in a way that leads to significant electrolyte exchange affecting systemic acid-base balance. *Vomiting causing metabolic alkalosis* - **Vomiting** leads to the loss of **gastric acid (HCl)**, which results in **hypochloremia** and metabolic alkalosis, not acidosis. - The loss of hydrogen ions and chloride from the stomach causes an increase in serum bicarbonate to maintain charge neutrality.

Question 840: Positive urinary anion gap is found in which of the following conditions?

A. Diabetic ketoacidosis
B. Renal tubular acidosis (Correct Answer)
C. Diarrhea
D. Alcoholic ketoacidosis

Explanation: ***Renal tubular acidosis*** - **Renal tubular acidosis (RTA)** results in impaired renal acid excretion, leading to a **positive urinary anion gap** [1]. - This occurs because the kidneys are unable to excrete sufficient amounts of **ammonium (NH4+)**, which is a primary urinary cation that balances excreted anions [1]. *Alcoholic ketoacidosis* - While alcoholic ketoacidosis causes a **high serum anion gap metabolic acidosis**, the urinary anion gap is typically **negative** due to increased excretion of ammonium to excrete excess acids. - The ketoacids (beta-hydroxybutyrate, acetoacetate) are the unmeasured anions contributing to the serum anion gap. *Diabetic ketoacidosis* - Similar to alcoholic ketoacidosis, **diabetic ketoacidosis (DKA)** presents with a high serum anion gap and a **negative urinary anion gap**. - The body compensates for the metabolic acidosis by increasing **ammonium excretion** in the urine. *Diarrhea* - Severe diarrhea causes **hyperchloremic metabolic acidosis** with a **normal serum anion gap** [1]. - The increased loss of bicarbonate in stool leads to renal compensation with increased acid excretion, resulting in a **negative urinary anion gap** as ammonium excretion rises.

Practice by Chapter

Acute Kidney Injury

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Chronic Kidney Disease

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Glomerular Diseases

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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

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Acid-Base Disorders

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Kidney in Systemic Diseases

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Kidney Stones and Obstructive Uropathy

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Hypertension in Kidney Disease

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Nephrology — MCQs

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