Nephrology Practice Questions

Q: In nephrotic syndrome, what is the essential feature?

Proteinuria. Nephrotic syndrome is a clinical complex characterized by a triad of findings resulting from increased glomerular permeability. While all four options are components of the syndrome, **Proteinuria** is the essential, primary feature that initiates the entire pathophysiological cascade [1]. **1. Why Proteinuria is the Correct Answer:** The hallmark of nephrotic syndrome is **massive proteinuria (>3.5 g/24 hours)**. It occurs due to the loss of the glomerular filtration barrier's integrity (either charge-selective or size-selective) [1]. This massive loss of protein is the "sine qua non" of the condition; without nephrotic-range proteinuria, the subsequent clinical and biochemical features cannot develop [1]. **2. Why other options are incorrect:** * **Hypoalbuminemia (<3 g/dL):** This is a *consequence* of massive proteinuria. While nearly always present, it is secondary to the urinary loss of albumin and increased hepatic catabolism [1]. * **Hyperlipemia:** This is a *compensatory* response. The liver increases the synthesis of lipoproteins (VLDL, LDL) to maintain oncotic pressure in response to low albumin [1]. * **Edema:** This is the *clinical manifestation*. It occurs due to decreased plasma oncotic pressure (Starling forces) and secondary sodium/water retention [1]. It is the most common presenting symptom but not the defining physiological event. **High-Yield Clinical Pearls for NEET-PG:** * **Definition:** Nephrotic range proteinuria is >3.5 g/day in adults or >40 mg/m²/hr in children. * **Mnemonic (NAPH):** **N**ephrotic range proteinuria, **A**lbumins low, **P**uffiness (Edema), **H**yperlipidemia. * **Most Common Cause:** Minimal Change Disease (Children); Focal Segmental Glomerulosclerosis (Adults worldwide); Membranous Nephropathy (Older adults) [2]. * **Hypercoagulability:** Patients are at high risk for Renal Vein Thrombosis due to the loss of Antithrombin III in urine.

Q: A 40-year-old man is found to have severe metabolic acidosis with a high anion gap. What is the most likely cause?

Methanol ingestion. ### Explanation **Correct Answer: B. Methanol ingestion** The primary diagnostic step in metabolic acidosis is calculating the **Anion Gap (AG)** using the formula: $Na^+ - (Cl^- + HCO_3^-)$. A normal AG is typically $12 \pm 2$ mEq/L. **Methanol ingestion** causes a **High Anion Gap Metabolic Acidosis (HAGMA)** [1]. When methanol is metabolized by alcohol dehydrogenase, it produces formic acid [2]. These unmeasured organic acid anions accumulate in the blood, replacing bicarbonate and increasing the anion gap [1], [2]. Other common causes of HAGMA are remembered by the mnemonic **MUDPILES** (Methanol, Uremia, DKA, Propylene glycol, Iron/INH, Lactic acidosis, Ethylene glycol, Salicylates). **Why the other options are incorrect:** * **Diarrhea (Option A):** This leads to a loss of bicarbonate-rich intestinal fluids. To maintain electroneutrality, the kidneys retain chloride, resulting in a **Normal Anion Gap Metabolic Acidosis (NAGMA)**, also known as hyperchloremic metabolic acidosis. * **Proximal RTA (Type 2) (Option C):** Caused by a defect in bicarbonate reabsorption in the proximal tubule. It results in NAGMA [4]. * **Distal RTA (Type 1) (Option D):** Caused by a failure of $H^+$ secretion in the distal tubule. It also results in NAGMA [4]. **High-Yield Clinical Pearls for NEET-PG:** 1. **Methanol Toxicity:** Classically presents with "snowfield vision" (optic papillitis) and can lead to permanent blindness or putaminal necrosis on MRI [2]. 2. **Osmolar Gap:** Methanol and Ethylene glycol are the two most common causes of HAGMA that also present with an **elevated Osmolar Gap** [1]. 3. **Treatment:** Fomepizole (inhibits alcohol dehydrogenase) is the preferred antidote; ethanol is an alternative [1]. Hemodialysis is indicated in severe cases [3].

Q: What is the diagnostic feature of chronic renal failure (CRF)?

Broad casts in urine. **Explanation:** The hallmark diagnostic feature of **Chronic Renal Failure (CRF)**, now more commonly referred to as Chronic Kidney Disease (CKD), is the presence of **Broad Casts** in the urinary sediment. [1] **1. Why Broad Casts are the Correct Answer:** Broad casts (often called "Renal Failure Casts") are significantly wider than ordinary casts. They form in the **collecting ducts** that have undergone compensatory hypertrophy and dilation due to the loss of surrounding functioning nephrons. Their presence indicates severe, long-standing parenchymal damage and a significantly reduced number of functioning nephrons, making them highly specific for chronic renal disease. **2. Why other options are incorrect:** * **Elevated Blood Urea:** This is a feature of **Azotemia**, which can occur in Prerenal (dehydration), Renal (AKI/CKD), or Postrenal (obstruction) conditions. It is not specific to the chronicity of renal failure. * **Proteinuria:** While common in CKD (especially diabetic nephropathy), it is also a hallmark of **Acute Glomerulonephritis** and **Nephrotic Syndrome**. It does not differentiate between acute and chronic states. [2] * **Bleeding Diathesis:** This occurs in advanced uremia due to **platelet dysfunction** (impaired aggregation). While seen in CRF, it is a complication of the uremic state rather than a diagnostic feature of the renal failure itself. **High-Yield Clinical Pearls for NEET-PG:** * **Waxy Casts:** Often found alongside broad casts; they represent the end-stage of cast evolution and indicate extreme stasis in the nephron. * **Small Kidney Size:** On ultrasound (<9 cm), this is the most reliable sign of CRF, *except* in Diabetes, Amyloidosis, and Polycystic Kidney Disease (PKD), where kidneys may be normal or enlarged. * **Anemia in CRF:** Usually normocytic normochromic due to decreased Erythropoietin production.

Q: Which of the following is a sign of Acute Tubular Necrosis (ATN)?

Blood Urea Nitrogen (BUN)/Creatinine ratio <20. **Explanation:** Acute Tubular Necrosis (ATN) is the most common cause of intrinsic acute kidney injury (AKI). It results from structural damage to the tubular epithelial cells, leading to a loss of the kidney's ability to concentrate urine and reabsorb electrolytes. **1. Why Option C is Correct:** In ATN, the damaged tubules cannot reabsorb urea effectively. In contrast to pre-renal azotemia (where urea is avidly reabsorbed along with water, leading to a ratio >20:1), the **BUN/Creatinine ratio in ATN remains low ( 2%**. * **RFI 2**. * **Urine Osmolality >1.010 (Option D):** This is a distractor. In ATN, the kidneys lose the ability to concentrate urine, resulting in **isosthenuria** (urine osmolality fixed at ~300 mOsm/kg, similar to plasma) and a low specific gravity (~1.010). A high urine osmolality (>500 mOsm/kg) is characteristic of pre-renal AKI. **Clinical Pearls for NEET-PG:** * **Microscopy:** Look for **"Muddy brown" granular casts**, which are pathognomonic for ATN. * **Urine Sodium:** Typically **>40 mEq/L** in ATN (vs. <20 mEq/L in pre-renal). * **Common Causes:** Ischemia (prolonged hypotension) or Nephrotoxins (Aminoglycosides, Contrast media, Myoglobinuria).

Question 1

What are the causes of pulmonary renal syndrome?

Accepted Answer

All of the above

Answer

Leptospirosis

Answer

Hanta virus

Answer

Paraquat poisoning

Question 2

What is the best therapy for hepato-renal syndrome?

Accepted Answer

Liver transplantation

Answer

Renal transplantation

Answer

Transjugular intrahepatic portosystemic shunt

Answer

Dialysis

Question 3

In nephrotic syndrome, what is the essential feature?

Accepted Answer

Proteinuria

Answer

Hypoalbuminemia

Answer

Hyperlipemia

Answer

Edema

Question 4

A female patient presents with an upper respiratory tract infection. After 15 days, she develops hematuria. What is the probable diagnosis?

Accepted Answer

Post-streptococcal glomerulonephritis

Answer

IgA nephropathy

Answer

Wegener's granulomatosis

Answer

Henoch-Schönlein purpura

Question 5

A 40-year-old man is found to have severe metabolic acidosis with a high anion gap. What is the most likely cause?

Accepted Answer

Methanol ingestion

Answer

Diarrhea

Answer

Proximal renal tubular acidosis

Answer

Distal renal tubular acidosis

Question 6

What is the most common neurological disturbance observed in patients with Chronic Kidney Disease (CKD)?

Accepted Answer

Dementia

Answer

Seizures

Answer

Peripheral neuropathy

Answer

Restless leg syndrome

Question 7

What is the diagnostic feature of chronic renal failure (CRF)?

Accepted Answer

Broad casts in urine

Answer

Elevated blood urea

Answer

Proteinuria

Answer

Bleeding diathesis

Question 8

Which of the following is a sign of Acute Tubular Necrosis (ATN)?

Accepted Answer

Blood Urea Nitrogen (BUN)/Creatinine ratio <20

Answer

Fractional Excretion of Sodium (FENa) <1

Answer

Renal Failure Index (RFI) <1

Answer

Urine osmolality >1.010

Question 9

A patient presents with hypotension in a confused state and metabolic alkalosis. Which of the following tests will best suggest the diagnosis?

Accepted Answer

Urine Na+

Answer

Urine pH

Answer

Urine Cl-

Answer

Urine K+

Question 10

A patient presenting with hemoptysis and renal failure with anti-basement membrane antibodies has which of the following conditions?

Accepted Answer

Goodpasture syndrome

Answer

Wegener's granulomatosis

Answer

Churg-Strauss syndrome

Answer

Henoch-Schonlein purpura

Nephrology — MCQs

Nephrology — MCQs

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