Nephrology Practice Questions

Q: A 5-year-old child develops the sudden onset of bloody diarrhea, vomiting of blood, hematuria, and renal failure following a flulike gastrointestinal illness. The blood urea nitrogen (BUN) level is markedly increased, but fibrin degradation products and blood clotting times are within normal limits. A peripheral blood smear reveals poikilocytes, schistocytes, and a decrease in the number of platelets. No fever or neurologic symptoms are present. What is the best diagnosis for this patient?

Hemolytic-uremic syndrome (HUS). ### Explanation The clinical presentation describes the classic triad of **Hemolytic-Uremic Syndrome (HUS)**: Microangiopathic hemolytic anemia (MAHA), thrombocytopenia, and acute kidney injury (AKI). **1. Why HUS is the Correct Answer:** HUS typically follows a prodromal gastrointestinal illness (often caused by Shiga toxin-producing *E. coli* O157:H7). The toxin causes endothelial damage in the renal microvasculature, leading to platelet activation and microthrombi formation. As RBCs pass through these partially occluded vessels, they are mechanically shredded, resulting in **schistocytes** (fragmented cells) and **poikilocytes**. The consumption of platelets leads to thrombocytopenia, while the localized thrombi in the kidney cause renal failure (elevated BUN/Creatinine) and hematuria. **2. Why the Other Options are Incorrect:** * **DIC:** While DIC also features schistocytes and low platelets, it is characterized by **abnormal coagulation profiles** (prolonged PT/aPTT) and elevated Fibrin Degradation Products (FDPs). In this case, clotting times and FDPs are normal, ruling out DIC. * **TTP:** TTP shares the features of HUS but is more common in adults and typically presents with a **pentad** that includes fever and prominent **neurologic symptoms**, both of which are absent here. * **ITP:** ITP presents with isolated thrombocytopenia. It does not cause schistocytes, hemolytic anemia, or renal failure. **3. NEET-PG High-Yield Pearls:** * **Most common cause of AKI in children:** HUS. * **Classic Triad:** Hemolytic anemia (Coombs negative) + Thrombocytopenia + Renal failure. * **Key Lab Finding:** Normal PT/aPTT (distinguishes HUS from DIC). * **Management:** Primarily supportive (fluid/electrolyte balance, dialysis if needed). **Antibiotics and anti-motility agents are contraindicated** as they may increase toxin release and worsen the condition.

Q: A male child presents with repeated urinary infections and failure to gain weight. A MCU was carried out as shown in the provided image. What is the most probable diagnosis?

Posterior urethral valve. ***Posterior urethral valve*** - **Male child** with **recurrent UTIs** and **failure to thrive** along with characteristic **MCU findings** showing **dilated posterior urethra** and **trabeculated bladder** strongly suggests posterior urethral valve. - **PUV** causes **bladder outlet obstruction** leading to **vesicoureteral reflux**, **hydronephrosis**, and the classic **keyhole sign** on imaging studies. *Meatal stenosis* - Typically presents with **narrow urinary stream** and **dysuria** but does not cause the severe **bladder trabeculation** and **upper tract dilatation** seen on MCU. - Would show **narrowing at the urethral meatus** rather than **posterior urethral dilatation** characteristic of this case. *Bladder diverticulum* - Presents as **outpouching of bladder wall** on imaging and may cause **urinary stasis** but is uncommon in children. - Does not typically cause the **posterior urethral dilatation** and **keyhole appearance** seen in posterior urethral valves. *Bladder polyp* - Usually presents as **filling defects** within the bladder on imaging rather than **urethral dilatation**. - **Benign bladder masses** are rare in children and do not cause the characteristic **obstructive uropathy** pattern seen in this case.

Q: Shigella associated hemolytic uremic syndrome is associated with all of the following except?

Hyperkalemia. **Explanation:** Hemolytic Uremic Syndrome (HUS) is a clinical triad characterized by **Microangiopathic Hemolytic Anemia (MAHA)**, **Thrombocytopenia**, and **Acute Kidney Injury (AKI)**. In the context of *Shigella dysenteriae* type 1, the Shiga toxin causes endothelial damage, primarily in the renal vasculature. **Why Hyperkalemia is the correct answer (the "Except"):** While AKI typically leads to hyperkalemia due to decreased potassium excretion, Shigella-associated HUS is a unique exception. *Shigella* infection often causes severe **secretory diarrhea**, leading to significant gastrointestinal loss of potassium. Consequently, patients frequently present with **hypokalemia** or normal potassium levels, despite the presence of renal failure. **Analysis of Incorrect Options:** * **Thrombocytopenia:** This is a hallmark of HUS. Platelets are consumed during the formation of microthrombi in damaged small blood vessels. * **Neurological symptoms:** These occur in approximately 25–50% of cases due to metabolic encephalopathy or microvascular thrombi in the CNS, presenting as irritability, seizures, or altered consciousness. * **Renal microthrombi:** The pathophysiology involves Shiga toxin-induced endothelial injury, leading to the deposition of fibrin-platelet thrombi within the glomerular capillaries, which causes the characteristic renal failure. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Triad:** Anemia (Coombs negative), Thrombocytopenia, and Renal failure. * **Peripheral Smear:** Will show **Schistocytes** (fragmented RBCs) and helmet cells. * **D+ HUS vs. D- HUS:** D+ (Diarrhea-associated) is most commonly caused by *E. coli* O157:H7 (Verotoxin) or *Shigella* (Shiga toxin). * **Management:** Primarily supportive (fluid/electrolyte balance, dialysis). **Antibiotics and anti-motility agents are generally avoided** as they may worsen toxin release.

Q: What is true about minimal change disease?

Peak incidence is between 2-4 years of age.. **Explanation:** Minimal Change Disease (MCD) is the most common cause of Nephrotic Syndrome in children, accounting for approximately 80-90% of cases in the pediatric age group. **1. Why Option A is correct:** The peak incidence of MCD occurs in early childhood, specifically between **2 to 4 years of age**. It is more common in boys than girls (2:1 ratio). In this age group, the presence of nephrotic syndrome is so strongly associated with MCD that a renal biopsy is usually deferred, and a trial of steroids is initiated immediately. **2. Why the other options are incorrect:** * **Option B:** Renal failure is **rare** in MCD. The prognosis is generally excellent, and most children maintain normal renal function. If a patient presents with persistent hypertension or azotemia, alternative diagnoses like Focal Segmental Glomerulosclerosis (FSGS) should be considered. * **Option C:** Steroids (Prednisolone) are the **mainstay of treatment**. Over 90% of children with MCD are "Steroid Sensitive," meaning they achieve complete remission within 4-8 weeks of therapy. * **Option D:** While MCD was traditionally associated with **selective proteinuria** (primarily albuminuria due to loss of the glomerular basement membrane's negative charge), this is no longer considered a pathognomonic or reliable diagnostic feature in modern clinical practice. The most definitive "true" epidemiological fact among the choices is the age of incidence. **NEET-PG High-Yield Pearls:** * **Light Microscopy:** Glomeruli appear normal (hence "Minimal Change"). * **Electron Microscopy (Gold Standard):** Shows **effacement (fusion) of podocyte foot processes**. * **Immunofluorescence:** Typically negative for immune deposits. * **Association:** Can be associated with Hodgkin’s Lymphoma in adults. * **Most common complication:** Infections (due to loss of IgG and complement factors in urine).

Q: A child presents with decreased serum calcium, increased serum phosphorus, and decreased urinary calcium and phosphorus. Which condition is most likely?

Chronic renal failure. **Explanation:** The biochemical profile of **decreased serum calcium**, **increased serum phosphorus**, and **decreased urinary excretion** of both is characteristic of **Chronic Renal Failure (CRF)**. In CRF, the kidneys cannot effectively excrete phosphorus, leading to **hyperphosphatemia**. High phosphorus levels directly complex with calcium and inhibit the enzyme 1-alpha-hydroxylase, leading to a deficiency of active Vitamin D (Calcitriol). This results in decreased intestinal calcium absorption (**hypocalcemia**). Because the Glomerular Filtration Rate (GFR) is severely reduced, the total filtered load of both calcium and phosphorus into the urine is significantly decreased, explaining the low urinary levels. **Analysis of Incorrect Options:** * **Renal Tubular Acidosis (RTA):** Typically presents with hypercalciuria (increased urinary calcium) due to the buffering of metabolic acidosis by bone, which releases calcium into the urine. * **Nutritional & Coeliac Rickets:** Both are forms of Vitamin D deficiency. While they present with low serum calcium, they characteristically show **low or normal serum phosphorus** (due to secondary hyperparathyroidism causing phosphaturia) and **increased** urinary phosphorus. **High-Yield Pearls for NEET-PG:** * **Secondary Hyperparathyroidism:** In CRF, hypocalcemia and hyperphosphatemia trigger a massive rise in PTH to normalize calcium at the expense of bone (Renal Osteodystrophy). * **FGF-23:** This hormone rises early in CRF to help excrete phosphorus, but eventually fails as GFR declines. * **Rule of Thumb:** If Phosphorus is **High**, think Renal Failure or Hypoparathyroidism. If Phosphorus is **Low**, think Rickets or PHP.

Q: Sustained severe hypertension in children is most commonly suggestive of:

Renal parenchymal disease. **Explanation:** In the pediatric population, the etiology of hypertension is predominantly **secondary** (identifiable cause), unlike in adults where primary (essential) hypertension is more common. **Why Renal Parenchymal Disease is correct:** Renal diseases are the **most common cause of secondary hypertension** in children, accounting for approximately 70-80% of cases. **Renal parenchymal diseases** (such as Glomerulonephritis, Reflux Nephropathy, and Polycystic Kidney Disease) lead to sustained severe hypertension through mechanisms involving sodium retention, volume expansion, and activation of the Renin-Angiotensin-Aldosterone System (RAAS). **Analysis of Incorrect Options:** * **Coarctation of Aorta:** While a classic cause of upper extremity hypertension in children, it is less common than renal causes. It should be suspected if there is a significant BP differential between upper and lower limbs or diminished femoral pulses. * **Pheochromocytoma:** This is a rare catecholamine-secreting tumor in children. While it causes severe hypertension, it is often paroxysmal (episodic) rather than sustained and represents a very small fraction of pediatric cases. * **Drug-induced Hypertension:** Certain drugs (steroids, sympathomimetics, or ADHD medications) can elevate BP, but these are transient and secondary to external intake rather than a primary disease process. **High-Yield Clinical Pearls for NEET-PG:** * **Rule of Thumb:** The younger the child and the higher the blood pressure, the more likely it is to be a secondary cause. * **Most common cause overall (Pediatrics):** Renal Parenchymal Disease. * **Most common renovascular cause:** Fibromuscular Dysplasia (FMD) or Takayasu Arteritis (in older children). * **Initial Investigation:** Urinalysis, BUN/Creatinine, and Renal Ultrasound are the first-line steps in evaluating pediatric hypertension.

Question 1

A 5-year-old child develops the sudden onset of bloody diarrhea, vomiting of blood, hematuria, and renal failure following a flulike gastrointestinal illness. The blood urea nitrogen (BUN) level is markedly increased, but fibrin degradation products and blood clotting times are within normal limits. A peripheral blood smear reveals poikilocytes, schistocytes, and a decrease in the number of platelets. No fever or neurologic symptoms are present. What is the best diagnosis for this patient?

Accepted Answer

Hemolytic-uremic syndrome (HUS)

Answer

Autoimmune thrombocytopenic purpura (ITP)

Answer

Disseminated intravascular coagulopathy (DIC)

Answer

Thrombotic thrombocytopenic purpura (TTP)

Question 2

A male child presents with repeated urinary infections and failure to gain weight. A MCU was carried out as shown in the provided image. What is the most probable diagnosis?

Accepted Answer

Posterior urethral valve

Answer

Meatal stenosis

Answer

Bladder diverticulum

Answer

Bladder polyp

Question 3

Shigella associated hemolytic uremic syndrome is associated with all of the following except?

Accepted Answer

Hyperkalemia

Answer

Thrombocytopenia

Answer

Neurological symptom

Answer

Renal micro thrombi

Question 4

What is true about minimal change disease?

Accepted Answer

Peak incidence is between 2-4 years of age.

Answer

Renal failure is usually present in adolescence.

Answer

Steroids are not effective medications for treatment.

Answer

It is characterized by selective proteinuria.

Question 5

What is the treatment of choice for a 4-month-old female child presenting with grade IV Vesico-Ureteral Reflux (VUR) without dilation of the urinary bladder?

Accepted Answer

Trimethoprim-sulfamethoxazole plus follow-up

Answer

Re-implantation of the ureter

Answer

Injection of collagen at the ureteric orifices

Answer

Bilateral ureterostomy

Question 6

A child presents with decreased serum calcium, increased serum phosphorus, and decreased urinary calcium and phosphorus. Which condition is most likely?

Accepted Answer

Chronic renal failure

Answer

Renal tubular acidosis

Answer

Nutritional rickets

Answer

Coeliac rickets

Question 7

Sustained severe hypertension in children is most commonly suggestive of:

Accepted Answer

Renal parenchymal disease

Answer

Coarctation of aorta

Answer

Pheochromocytoma

Answer

Drug induced hypertension

Question 8

What is the definition of hypertension in children?

Accepted Answer

Average systolic blood pressure (SBP) and/or diastolic BP that is >=95th percentile for age, sex, and height on >=3 occasions

Answer

Average systolic blood pressure (SBP) and/or diastolic BP that is >=95th percentile for age, sex, and height on >=2 occasions

Answer

Average systolic blood pressure (SBP) and/or diastolic BP that is >=90th percentile for age, sex, and height on >=2 occasions

Answer

Average systolic blood pressure (SBP) and/or diastolic BP that is >=90th percentile for age, sex, and height on >=3 occasions

Question 9

What is true about Post-Streptococcal Glomerulonephritis?

Accepted Answer

Glomerulonephritis secondary to skin infection is more common in summer

Answer

50% of cases occur after pharyngitis

Answer

Early treatment of pharyngitis eliminates the risk of PSGN

Answer

Recurrence is seen

Question 10

Frequent relapse in Nephrotic syndrome implies which of the following definitions?

Accepted Answer

Two or more relapses in a 6-month period following initial response

Answer

Three or more relapses in a 1-year period

Answer

Relapse every month

Answer

Relapse every 3 months

Nephrology — MCQs

Nephrology — MCQs

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