Nephrology Practice Questions

Q: What is the most common cause of hydronephrosis in children?

Pelviureteric junction (PUJ) obstruction. **Explanation:** **Pelviureteric Junction (PUJ) Obstruction** is the most common cause of congenital hydronephrosis in children. It occurs due to an anatomical or functional narrowing at the junction where the renal pelvis meets the ureter, leading to impaired urine flow and subsequent dilatation of the renal pelvis and calyces. **Analysis of Options:** * **A. PUJ Obstruction (Correct):** It is the leading cause of both neonatal and pediatric hydronephrosis. It is most commonly unilateral and often detected on antenatal ultrasound. * **B. Ureterocele:** This is a cystic dilation of the distal ureter. While it can cause hydroureteronephrosis, it is much less common than PUJ obstruction. * **C. Posterior Urethral Valve (PUV):** This is the most common cause of **bilateral** hydronephrosis in **male** infants. While clinically significant and a common cause of bladder outlet obstruction, its overall incidence is lower than PUJ obstruction. * **D. Ectopic Ureters:** These occur when the ureter terminates outside the bladder trigone. While they can cause obstruction or reflux, they are a relatively rare cause of hydronephrosis. **Clinical Pearls for NEET-PG:** * **Most common cause of unilateral hydronephrosis:** PUJ Obstruction. * **Most common cause of bilateral hydronephrosis in males:** Posterior Urethral Valve (PUV). * **Gold standard investigation for PUJ Obstruction:** DTPA or MAG-3 scan (Diuretic Renography) to assess the degree of obstruction and renal function. * **Classic Presentation:** Often asymptomatic (detected antenatally) or may present as a palpable flank mass or episodic "Dietl’s crisis" (intermittent flank pain associated with high fluid intake).

Q: What is the daily maintenance fluid requirement for a child weighing 10 kg?

1000 ml/day. The calculation of maintenance fluid in pediatrics is based on the **Holliday-Segar Formula**, which estimates caloric expenditure and subsequent fluid needs based on body weight. This is a high-yield concept for NEET-PG. ### **Explanation of the Correct Answer** According to the Holliday-Segar rule, maintenance fluid requirements are calculated as follows: * **First 10 kg:** 100 ml/kg/day * **Next 10 kg (11–20 kg):** 1000 ml + 50 ml/kg for every kg over 10 kg * **Each kg above 20 kg:** 1500 ml + 20 ml/kg for every kg over 20 kg For a child weighing **10 kg**, the calculation is: $10\text{ kg} \times 100\text{ ml/kg/day} = \mathbf{1000\text{ ml/day}}$. ### **Analysis of Incorrect Options** * **B (800 ml/day):** This would be the requirement for an 8 kg infant. * **C (500 ml/day):** This is insufficient for a 10 kg child and represents the requirement for a 5 kg infant. * **D (1200 ml/day):** This would be the requirement for a 14 kg child ($1000\text{ ml} + [4\text{ kg} \times 50\text{ ml}]$). ### **Clinical Pearls for NEET-PG** 1. **Hourly Rate Rule (4-2-1 Rule):** To calculate the hourly infusion rate: * 0–10 kg: 4 ml/kg/hr * 11–20 kg: 40 ml + 2 ml/kg for every kg > 10 * >20 kg: 60 ml + 1 ml/kg for every kg > 20 2. **Neonatal Exception:** The Holliday-Segar formula is **not** used for neonates (<28 days), as their fluid requirements change daily during the first week of life. 3. **Composition:** Isotonic solutions (e.g., 0.9% Normal Saline in D5) are now preferred over hypotonic solutions to prevent hospital-acquired hyponatremia.

Q: What is the primary pathology underlying edema in nephrotic syndrome?

Sodium and water retention. **Explanation:** The primary pathology underlying edema in nephrotic syndrome is **Sodium and water retention**, specifically through the **"Overfill Mechanism."** While traditional teaching emphasized the "Underfill" theory (low albumin leading to decreased oncotic pressure), modern evidence and NEET-PG standards prioritize the Overfill theory as the primary driver. 1. **Why the correct answer is right:** In nephrotic syndrome, there is a primary intrarenal defect in the distal nephron (specifically the ENaC channels in the cortical collecting duct). This leads to **primary sodium retention** regardless of the plasma volume status. This excess sodium causes water retention, leading to an expansion of the extracellular fluid (ECF) volume, which then leaks into the interstitium, causing edema. 2. **Why the incorrect options are wrong:** * **Reduced plasma protein concentration:** While hypoalbuminemia occurs, it is considered a *contributory* factor (Underfill theory) rather than the primary initiator of edema in most adult and many pediatric cases. * **Increased venous pressure:** This is the mechanism for edema in Congestive Heart Failure (CHF), not nephrotic syndrome. * **Hyperlipidemia:** This is a diagnostic criterion for nephrotic syndrome (due to increased hepatic lipoprotein synthesis), but it does not physiologically contribute to edema formation. **High-Yield Clinical Pearls for NEET-PG:** * **Overfill Theory:** Primary renal sodium retention (most common in adults/MCD). * **Underfill Theory:** Decreased oncotic pressure → Secondary activation of RAAS (more common in severe hypoalbuminemia <2.0 g/dL). * **Site of Sodium Retention:** The **ENaC (Epithelial Sodium Channel)** in the collecting duct is the chief site of resistance to ANP and increased sodium reabsorption. * **Initial Sign:** Edema in nephrotic syndrome typically presents first as **periorbital puffiness** (dependent edema).

Q: Nephrotic range of proteinuria is defined as:

greater than 40 mg/m2/hr. **Explanation:** In pediatric nephrology, defining the severity of proteinuria is crucial for diagnosing Nephrotic Syndrome. The hallmark of this condition is "massive" or **nephrotic-range proteinuria**, which leads to hypoalbuminemia and subsequent edema. **Why Option B is correct:** The standard definition for nephrotic-range proteinuria in children is a protein excretion rate of **>40 mg/m²/hr**. This value is derived from timed urine collections and is the most precise metric used in clinical guidelines (such as ISPN and KDIGO) to differentiate nephrotic syndrome from milder forms of glomerular injury. **Analysis of Incorrect Options:** * **Option A (>30 mg/m²/hr):** This is a sub-nephrotic range. While abnormal, it does not meet the diagnostic threshold for Nephrotic Syndrome. * **Option C (>2 gm/m²/24hrs):** While 1 gram/m²/24hrs is sometimes used as a threshold for "heavy" proteinuria, the specific diagnostic cutoff for nephrotic range is generally cited as **>1 gram/m²/day** or more accurately **>50 mg/kg/day**. 2 grams is an arbitrary figure in this context. * **Option D (>4 gm/m²/24hrs):** This value is excessively high and far exceeds the minimum diagnostic criteria. **High-Yield Clinical Pearls for NEET-PG:** * **Spot Urine Protein/Creatinine Ratio (uPCR):** In clinical practice, a ratio of **>2 mg/mg** (or >200 mg/mmol) is considered nephrotic range. * **Dipstick Grading:** Nephrotic syndrome typically shows **3+ or 4+** on a urine dipstick. * **Definition of Nephrotic Syndrome:** It is a clinical triad of Nephrotic-range proteinuria, Hypoalbuminemia (<2.5 g/dL), and Edema. Hyperlipidemia is a frequent association but not always required for diagnosis. * **Normal Proteinuria:** In children, normal protein excretion is **<4 mg/m²/hr**.

Q: Which of the following is NOT true about Bartter syndrome?

Hyperkalemic metabolic alkalosis. **Explanation:** **Bartter syndrome** is a group of autosomal recessive disorders characterized by a defect in the thick ascending limb (TAL) of the loop of Henle, mimicking the effect of chronic loop diuretic (furosemide) use. **1. Why Option A is the correct answer (The False Statement):** The hallmark of Bartter syndrome is **Hypokalemic metabolic alkalosis**, not hyperkalemic. The defect in the TAL leads to failure of sodium, chloride, and potassium reabsorption. The resulting increased sodium delivery to the distal tubule triggers aldosterone secretion, which promotes potassium and hydrogen ion excretion in the collecting duct, leading to hypokalemia and metabolic alkalosis. **2. Analysis of Incorrect Options (True Statements):** * **Option B:** Antenatal/Neonatal Bartter syndrome (Type IV) is caused by mutations in the **BSND gene (encoding Barttin)**. This type is uniquely associated with sensorineural deafness (ototoxicity) because Barttin is essential for chloride channels in both the kidney and the inner ear. * **Option C:** The primary pathophysiology involves a defect in the **NKCC2 transporter**, ROMK channel, or ClC-Kb channel, all of which result in decreased potassium and solute reabsorption in the TAL. * **Option D:** Most forms of Bartter syndrome (Types I-IV) follow an **autosomal recessive** inheritance pattern. **High-Yield Clinical Pearls for NEET-PG:** * **Bartter vs. Gitelman:** Bartter presents early (infancy) with **hypercalciuria** (stones), whereas Gitelman presents later (adolescence) with **hypocalciuria** and hypomagnesemia. * **Mnemonic:** **B**artter is like **B**loop (Loop diuretics); **G**itelman is like **G**thiazide (Thiazide diuretics). * **Clinical Features:** Polyhydramnios (antenatal), failure to thrive, and "floppy baby" due to hypokalemia.

Q: A newborn male presents with urinary retention, lethargy and a distended bladder. Antenatal ultrasound showed a "keyhole sign" with a thickened bladder wall. Which of the following is the most likely diagnosis?

Posterior urethral valves. ***Posterior urethral valves***- The **"keyhole sign"** seen on antenatal ultrasound, characterized by a dilated posterior urethra and a thickened, distended bladder, is highly specific for **posterior urethral valves (PUV)**.- PUV is the most common cause of severe **lower urinary tract obstruction** in male newborns, leading directly to symptoms like lethargy, a palpable **distended bladder**, and urinary retention.*Hypospadias*- *Hypospadias* is an abnormal location of the **urethral meatus** on the ventral aspect of the penis.- It does not cause the severe **obstructive uropathy** (like urinary retention and bladder distension) or the **keyhole sign** observed in this patient.*Vesicoureteral reflux*- *Vesicoureteral reflux* (VUR) involves the reflux of urine from the bladder back up to the ureters and is typically a **non-obstructive** cause of hydronephrosis and UTIs.- While VUR can coexist with PUV, it is the secondary phenomenon, and VUR itself does not cause the primary **urethral obstruction** or the characteristic **keyhole appearance**.*Neurogenic bladder*- A *neurogenic bladder* results from impaired nerve supply, often due to conditions like **spina bifida**, leading to poor bladder emptying.- While it can cause retention, the unique finding of the **keyhole sign** points specifically to a fixed, **anatomical obstruction** in the posterior urethra, which is not characteristic of neurological issues.

Q: What is the recommended treatment for nephrotic syndrome in children?

Steroids. ***Steroids***- **Corticosteroids** (typically Prednisone/Prednisolone) are the recommended **first-line therapy** for pediatric nephrotic syndrome, as *minimal change disease* (**MCD**) is the most common cause (90% of cases).- The vast majority of children with MCD are **steroid-sensitive**, exhibiting remission (proteinuria cessation) within 2-4 weeks of high-dose treatment.*Steroids and cyclophosphamide*- Combination therapy including **cyclophosphamide** is typically reserved for children who show **steroid dependence** or **frequent relapses**, not for initial therapy.- Adding cyclophosphamide as a first-line agent is unnecessary due to its potential for significant **gonadal toxicity** and other systemic side effects.*Cyclophosphamide*- **Cyclophosphamide** is a powerful **second-line immunosuppressive agent** used primarily for children who are steroid-dependent or **steroid-resistant**.- Using it as initial monotherapy is inappropriate because children with MCD usually respond well to steroids alone, avoiding risks like **myelosuppression**.*ACE inhibitors*- **Angiotensin-converting enzyme (ACE) inhibitors** are used primarily to reduce **proteinuria** by lowering **glomerular hydrostatic pressure**.- Their role is generally adjunctive management for resistant proteinuria or for treating associated **hypertension**, not as the primary agent to induce remission.

Q: Following urine microscopy and examination, a child is found to have hematuria and RBC casts in the urine. What is the probable cause for this?

Post-streptococcal glomerulonephritis (PSGN). ***Post-streptococcal glomerulonephritis (PSGN)***- RBC casts are highly indicative of **active glomerulonephritis**, demonstrating that red blood cells have leaked through damaged glomeruli and aggregated in the renal tubules.- **PSGN** is the most common cause of acute nephritic syndrome in children, typically following a *Streptococcal* infection, characterized by **hematuria**, hypertension, and mild proteinuria.*Focal segmental glomerulosclerosis (FSGS)*- FSGS almost universally presents as **nephrotic syndrome**, characterized by heavy **proteinuria**, profound edema, and hypoalbuminemia.- While microscopic hematuria may be present, the finding of **RBC casts** is highly uncommon and points away from a primary diagnosis of FSGS.*Membranoproliferative glomerulonephritis (MPGN)*- MPGN often presents with a **mixed nephrotic and nephritic picture**, including hematuria, but is less common acutely than PSGN in children.- PSGN presents with a very typical acute onset of **nephritic features** (hematuria, casts, hypertension) following infection, making it the more probable cause.*Minimal change disease*- This is the leading cause of **nephrotic syndrome** in children, defined by massive **proteinuria** with minimal to no damage visible on light microscopy.- **Minimal change disease** classically presents without significant hematuria and **RBC casts** are virtually absent.

Question 1

What is the most common cause of hydronephrosis in children?

Accepted Answer

Pelviureteric junction (PUJ) obstruction

Answer

Ureterocele

Answer

Posterior urethral valve

Answer

Ectopic ureter

Question 2

What is the frequency of renal involvement in Henoch-Schonlein Purpura (HSP)?

Accepted Answer

40-60%

Answer

20-40%

Answer

>80%

Answer

10%

Question 3

What is the daily maintenance fluid requirement for a child weighing 10 kg?

Accepted Answer

1000 ml/day

Answer

800 ml/day

Answer

500 ml/day

Answer

1200 ml/day

Question 4

What is the primary pathology underlying edema in nephrotic syndrome?

Accepted Answer

Sodium and water retention

Answer

Reduced plasma protein concentration

Answer

Increased venous pressure

Answer

Hyperlipidemia

Question 5

Nephrotic range of proteinuria is defined as:

Accepted Answer

greater than 40 mg/m2/hr

Answer

greater than 30 mg/m2/hr

Answer

greater than 2 gm/m2/24hrs

Answer

greater than 4 gm/m2/24hrs

Question 6

Which of the following is NOT true about Bartter syndrome?

Accepted Answer

Hyperkalemic metabolic alkalosis

Answer

Presentation in neonates with ototoxicity and Barttin gene mutation

Answer

Decreased potassium absorption from the thick ascending limb of the loop of Henle

Answer

Autosomal recessive inheritance

Question 7

What is the daily water requirement for a child weighing 30 kg, with a height of 123 cm, and a body surface area (BSA) of 1 m²?

Accepted Answer

1700 ml

Answer

1300 ml

Answer

2000 ml

Answer

2500 ml

Question 8

A newborn male presents with urinary retention, lethargy and a distended bladder. Antenatal ultrasound showed a "keyhole sign" with a thickened bladder wall. Which of the following is the most likely diagnosis?

Accepted Answer

Posterior urethral valves

Answer

Hypospadias

Answer

Vesicoureteral reflux

Answer

Neurogenic bladder

Question 9

What is the recommended treatment for nephrotic syndrome in children?

Accepted Answer

Steroids

Answer

ACE inhibitors

Answer

Cyclophosphamide

Answer

Steroids and cyclophosphamide

Question 10

Following urine microscopy and examination, a child is found to have hematuria and RBC casts in the urine. What is the probable cause for this?

Accepted Answer

Post-streptococcal glomerulonephritis (PSGN)

Answer

Focal segmental glomerulosclerosis (FSGS)

Answer

Membranoproliferative glomerulonephritis (MPGN)

Answer

Minimal change disease

Nephrology — MCQs

Nephrology — MCQs

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