Urinary Calculi — MCQs
Most sensitive test to detect early renal tuberculosis is -
What is the most common type of stone found in the bladder?
Ultrasound is the investigation of choice for
A 50-year-old man has a history of frequent episodes of renal colic with high calcium renal stones. The most useful diuretic in the treatment of recurrent calcium stones is:
A 45-year-old Caucasian male with a history of chronic myeloid leukemia for which he is receiving chemotherapy presents to the emergency room with oliguria and colicky left flank pain. His serum creatinine is 3.0 mg/dL and his urine pH is 5.0. You diagnose nephrolithiasis. His kidney stones, however, are not visible on abdominal x-ray. His stone is most likely composed of which of the following?
A patient presents with persistent and severe pain in the lateral thigh and pubic regions, requiring hospital admission for observation and potential surgical intervention. Where is the ureteral stone most likely lodged?
Which of the following advice is not given to a 35-year-old female patient with recurrent renal stones?
Which of the following types of kidney stones are commonly associated with urinary tract infections?
An infant with severe dehydration secondary to diarrhea suddenly presents with flank mass and blood in urine. The most probable diagnosis is?
Which of the following potassium sparing diuretics cause renal stones?
Urinary Calculi Indian Medical PG Practice Questions and MCQs
Question 1: Most sensitive test to detect early renal tuberculosis is -
- A. MRI
- B. Intravenous urography (Correct Answer)
- C. USG
- D. CT
Explanation: ***Intravenous urography*** - **Intravenous urography (IVU/IVP)** is the **most sensitive imaging test** for detecting **early renal tuberculosis**, particularly for visualizing collecting system changes. - **Early renal TB** primarily affects the **pelvicalyceal system** before significant parenchymal involvement occurs. - **Classic early findings** on IVU include: **calyceal irregularities**, **papillary necrosis**, **infundibular stenosis**, **"moth-eaten" calyces**, and **"phantom calyx"** (non-visualizing calyx due to infundibular obstruction). - IVU provides **excellent functional and anatomical detail** of the urinary collecting system with contrast opacification, making subtle early changes highly visible. *CT* - **CT scan** is more sensitive for detecting **parenchymal lesions**, **calcifications**, **strictures**, and **advanced disease** with cavitation. - However, for **early disease** that primarily involves the collecting system mucosa, CT may not be as sensitive as IVU in demonstrating subtle mucosal irregularities. - CT is excellent for staging and detecting complications but is not the first-line modality for early diagnosis. *MRI* - **MRI** provides excellent soft tissue contrast and is useful for complex cases or when radiation exposure must be avoided. - It is generally reserved for **problem-solving** or **contraindications to CT/IVU**, not for initial screening of early renal TB. - MRI does not offer superior sensitivity compared to IVU for early collecting system changes. *USG* - **Ultrasonography (USG)** is a useful **initial screening tool** but has **limited sensitivity** for detecting early renal tuberculosis. - It is operator-dependent and may miss subtle mucosal changes in the collecting system. - USG is more effective for identifying **gross lesions** like hydronephrosis, large abscesses, or significant parenchymal destruction in advanced disease.
Question 2: 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 3: Ultrasound is the investigation of choice for
- A. Somatostatinoma
- B. Intraductal Pancreatic calculi
- C. Urethral stricture
- D. Blunt abdominal trauma (Correct Answer)
Explanation: ***Blunt abdominal trauma*** - **Focused Assessment with Sonography for Trauma (FAST) exam** is the initial imaging modality of choice for rapidly detecting **intra-abdominal free fluid** (hemoperitoneum) in hemodynamically unstable patients with blunt abdominal trauma due to its speed, portability, and non-invasiveness. - It helps guide the need for further imaging or surgical intervention, making it critical in the acute setting. *Somatostatinoma* - Diagnosed primarily through biochemical tests (elevated **somatostatin levels**) and imaging like **CT, MRI, or somatostatin receptor scintigraphy (SRS)**, which are superior for localizing these rare neuroendocrine tumors. - Although ultrasound can sometimes detect pancreatic masses, it is not the **investigation of choice** for definitive diagnosis or staging of somatostatinomas. *Intraductal Pancreatic calculi* - Often best visualized with **Endoscopic Retrograde Cholangiopancreatography (ERCP)** or **Magnetic Resonance Cholangiopancreatography (MRCP)**, which provide detailed imaging of the pancreatic and bile ducts. - While transabdominal ultrasound can sometimes detect dilated ducts or large calculi, **Endoscopic Ultrasound (EUS)** is more sensitive and specific for intraductal pathologies, making routine transabdominal ultrasound not the primary choice. *Urethral stricture* - The gold standard for diagnosing urethral strictures is **urethrography** (retrograde urethrogram), which directly visualizes the stricture and its extent. - While ultrasound can sometimes be used to assess the urethra, it is less effective than urethrography for defining the length and severity of a stricture.
Question 4: A 50-year-old man has a history of frequent episodes of renal colic with high calcium renal stones. The most useful diuretic in the treatment of recurrent calcium stones is:
- A. Furosemide
- B. Hydrochlorothiazide (Correct Answer)
- C. Acetazolamide
- D. Spironolactone
Explanation: ***Hydrochlorothiazide*** - **Thiazide diuretics** reduce urinary calcium excretion by increasing calcium reabsorption in the distal convoluted tubule. - This mechanism makes them effective in preventing the recurrence of **calcium oxalate** and **calcium phosphate kidney stones**. *Furosemide* - **Loop diuretics** like furosemide increase urinary calcium excretion, which would *aggravate* rather than prevent calcium stone formation. - This effect is due to inhibiting sodium-potassium-chloride reabsorption in the **loop of Henle**, thereby reducing calcium reabsorption. *Spironolactone* - **Spironolactone** is a potassium-sparing diuretic that acts as an aldosterone antagonist, primarily affecting sodium and potassium balance. - It does not significantly impact urinary calcium excretion, and therefore, it is **not indicated** for the prevention of calcium renal stones. *Acetazolamide* - **Acetazolamide** is a carbonic anhydrase inhibitor that increases bicarbonate excretion and causes a metabolic acidosis. - It increases urinary pH and can potentially *promote* the formation of calcium phosphate stones in susceptible individuals.
Question 5: A 45-year-old Caucasian male with a history of chronic myeloid leukemia for which he is receiving chemotherapy presents to the emergency room with oliguria and colicky left flank pain. His serum creatinine is 3.0 mg/dL and his urine pH is 5.0. You diagnose nephrolithiasis. His kidney stones, however, are not visible on abdominal x-ray. His stone is most likely composed of which of the following?
- A. Uric acid (Correct Answer)
- B. Cystine
- C. Calcium phosphate
- D. Magnesium ammonium phosphate
- E. Calcium oxalate
Explanation: ***Uric acid*** - The patient has **chronic myeloid leukemia (CML)** and is receiving **chemotherapy**, which can cause a rapid turnover of cells, leading to **hyperuricemia** and the formation of uric acid stones. - Uric acid stones are **radiolucent** (not visible on X-ray) and are associated with a **low urine pH** (5.0 in this case). *Cystine* - Cystine stones are caused by a **genetic defect** in amino acid transport, leading to high urinary cystine levels. - While they are also **radiolucent**, there is no clinical information to suggest a genetic predisposition for cystinuria in this patient. *Calcium phosphate* - Calcium phosphate stones are typically **radio-opaque** and usually form in alkaline urine, which contradicts the patient's low urine pH [1]. - They are often associated with conditions like **renal tubular acidosis** or hyperparathyroidism [1]. *Magnesium ammonium phosphate* - These are also known as **struvite stones** and are highly suggestive of **urinary tract infections** with urea-splitting organisms (e.g., *Proteus*) [1]. - They tend to grow large, form **staghorn calculi**, and are **radio-opaque** [1]. *Calcium oxalate* - Calcium oxalate stones are the **most common type** of kidney stone and are **radio-opaque**, making them visible on X-ray. - They are typically associated with conditions causing **hypercalciuria** or hyperoxaluria, which are not explicitly indicated here, and they would be visible on the X-ray.
Question 6: A patient presents with persistent and severe pain in the lateral thigh and pubic regions, requiring hospital admission for observation and potential surgical intervention. Where is the ureteral stone most likely lodged?
- A. At the junction of the renal pelvis and ureter
- B. Midureter as it passes beneath the gonadal vessels
- C. At the pelvic brim (Correct Answer)
- D. In the intramural portion of the ureter where it penetrates the bladder
Explanation: ***At the pelvic brim*** - Stones lodged at the **pelvic brim**, particularly at the crossing of the **iliac vessels**, often cause severe, radiating pain to the **lateral thigh** and **groin/pubic** regions due to irritation of adjacent somatic nerves. - This location is a common site of impaction and can lead to significant obstruction and pain severe enough to warrant hospital admission. *At the junction of the renal pelvis and ureter* - Obstruction at the **ureteropelvic junction (UPJ)** typically causes **flank pain** radiating towards the abdomen, but not usually to the lateral thigh or pubic region. - While it can be severe, the pain distribution is characteristic of upper urinary tract distension. *Midureter as it passes beneath the gonadal vessels* - Stones in the **midureter** might cause pain that refers to the **anterior abdominal wall**, but it is less likely to specifically target the lateral thigh or pubic areas as intensely as stones at the pelvic brim. - Obstruction here can lead to hydronephrosis and colic, but the pain pattern is distinct. *In the intramural portion of the ureter where it penetrates the bladder* - Stones in the **intramural ureter** are associated with symptoms of **bladder irritation**, such as urinary frequency, urgency, and dysuria, along with referred pain to the **tip of the penis** or **labia**. - While painful, this location typically does not cause severe pain radiating to the lateral thigh or pubic region.
Question 7: Which of the following advice is not given to a 35-year-old female patient with recurrent renal stones?
- A. Increase water
- B. Restrict salt
- C. Restrict protein
- D. Restrict calcium intake (Correct Answer)
Explanation: ***Restrict calcium intake*** - For most types of renal stones (especially **calcium oxalate stones**), restricting dietary calcium is generally **not recommended** as it can ironically lead to increased oxalate absorption and higher stone formation risk. - Adequate calcium intake is important to bind dietary oxalate in the gut, reducing its absorption and subsequent excretion in the urine. *Increase water* - **Increased fluid intake** is a cornerstone in preventing all types of renal stones by promoting a higher urine volume, which dilutes stone-forming substances [1]. - This advice is crucial as it helps reduce the supersaturation of calcium, oxalate, and other mineral salts in the urine, making crystal formation less likely [1]. *Restrict protein* - **High animal protein intake** can increase the excretion of calcium, uric acid, and oxalate, while decreasing citrate excretion, all of which promote stone formation. - Limiting animal protein is a standard recommendation, particularly for patients with a history of **calcium oxalate** and **uric acid stones**. *Restrict salt* - High dietary sodium intake increases urinary calcium excretion and can promote the crystallization of calcium salts in the urine. - Therefore, **reducing salt intake** is a critical recommendation to lower urine calcium levels and prevent recurrent renal stones.
Question 8: Which of the following types of kidney stones are commonly associated with urinary tract infections?
- A. Struvite stones (Correct Answer)
- B. Cystine stones
- C. Xanthine stones
- D. Calcium oxalate stones
Explanation: ***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]
Question 9: An infant with severe dehydration secondary to diarrhea suddenly presents with flank mass and blood in urine. The most probable diagnosis is?
- A. Renal vein thrombosis (Correct Answer)
- B. Acute glomerulonephritis
- C. Lipoid nephrosis
- D. Pyelonephritis
Explanation: ***Renal vein thrombosis*** - **Dehydration**, especially in infants, is a significant risk factor for **renal vein thrombosis** due to increased blood viscosity and hypercoagulability - The sudden appearance of a **flank mass** (due to renal enlargement and hemorrhage) and **hematuria** (blood in urine) are classic signs of this condition - Classic triad includes flank mass, hematuria, and thrombocytopenia in the setting of predisposing factors like severe dehydration *Acute glomerulonephritis* - While it can cause hematuria, it typically presents with **edema**, **hypertension**, and **oliguria**, which are not mentioned in this scenario - A flank mass is not a typical presentation of acute glomerulonephritis - Usually follows streptococcal infection with latent period *Lipoid nephrosis* - This is a type of **nephrotic syndrome** characterized by **massive proteinuria**, edema, and normal renal function - Does not typically present with a flank mass or gross hematuria - More common presentation is generalized edema and frothy urine *Pyelonephritis* - This is a **bacterial infection of the kidney** that causes fever, flank pain, and dysuria - While it can cause microscopic hematuria, a sudden flank mass and gross hematuria are not typical presentations - Especially unlikely in the context of severe dehydration without signs of infection
Question 10: Which of the following potassium sparing diuretics cause renal stones?
- A. Triamterene (Correct Answer)
- B. Amiloride
- C. Eplerenone
- D. Spironolactone
Explanation: ***Triamterene*** - **Triamterene** is known particularly for its propensity to form **renal stones**, especially when combined with indomethacin or in patients with underlying kidney disease. - The drug itself is poorly soluble and can precipitate in the urine, forming stones or crystal aggregates. *Amiloride* - **Amiloride** is a potassium-sparing diuretic that inhibits sodium channels in the distal nephron, but it is **not associated with renal stone formation**. - Its mechanism of action does not involve precipitation in the urinary tract. *Eplerenone* - **Eplerenone** is a selective aldosterone receptor antagonist that prevents potassium excretion, but it has **not been linked to renal stone development**. - It works by blocking aldosterone's effects on the mineralocorticoid receptor, without crystal formation issues. *Spironolactone* - **Spironolactone** is a non-selective aldosterone antagonist, similar to eplerenone, and is **not recognized as a cause of renal stones**. - It competes with aldosterone for receptor binding in the collecting duct, leading to potassium sparing and sodium excretion.
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