Nephrology Practice Questions

Q: In tubular necrosis, what is the typical ratio of urine to plasma creatinine?

Approximately 20. In renal pathology, distinguishing between **Prerenal Azotemia** and **Acute Tubular Necrosis (ATN)** is a high-yield topic for NEET-PG. The Urine/Plasma (U/P) Creatinine ratio is a vital marker of the kidney's concentrating ability and tubular integrity. ### **Explanation of the Correct Answer** **Option A (Approximately 20)** is correct because, in ATN, the tubular epithelial cells are damaged and lose their ability to reabsorb water and concentrate the glomerular filtrate. * Creatinine is filtered but not reabsorbed. In a healthy kidney, water is reabsorbed, concentrating the creatinine in the urine (U/P ratio >40). * In **ATN**, the "leaky" and dysfunctional tubules cannot concentrate the urine effectively. This results in a **U/P Creatinine ratio of 40). [1] * **Options C & D:** These represent intermediate ranges. While clinical cases can overlap, for examination purposes, a ratio ** 40** points toward prerenal causes. ### **Clinical Pearls for NEET-PG** To differentiate Prerenal Azotemia from ATN, remember this high-yield table: | Feature | Prerenal Azotemia | Acute Tubular Necrosis (ATN) | | :--- | :--- | :--- | | **U/P Creatinine Ratio** | **> 40** | ** 2% | | **Urine Sodium (UNa)** | 40 mEq/L | | **Urine Osmolality** | > 500 mOsm/kg | < 350 mOsm/kg | | **Microscopy** | Hyaline casts | **Muddy brown granular casts** | **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 933-934.

Q: A patient presents with severe hyperkalemia and peaked T waves on ECG. What is the fastest method for shifting potassium intracellularly?

Insulin + glucose. The management of hyperkalemia is a high-yield topic for NEET-PG, focusing on three pillars: membrane stabilization, intracellular shifting, and elimination. **1. Why Insulin + Glucose is correct:** Insulin is the most potent and reliable agent for shifting potassium from the extracellular fluid (ECF) into the intracellular fluid (ICF). It works by stimulating the **Na+/K+-ATPase pump** in skeletal muscle and liver cells. Glucose (usually 50 ml of 25% or 50% Dextrose) is co-administered solely to prevent hypoglycemia. This effect begins within **10–20 minutes**, making it the fastest method for internal redistribution. **2. Analysis of Incorrect Options:** * **A. Calcium gluconate:** This is the *first* drug given in hyperkalemia with ECG changes, but it **does not lower potassium levels** [1]. It stabilizes the cardiac myocyte membrane by antagonizing the effects of potassium on the resting membrane potential [1]. * **B. Oral resins (e.g., Kayexalate):** These work by exchanging sodium for potassium in the gut. They are used for **elimination**, not shifting, and take hours to days to work. * **D. Sodium bicarbonate:** While it can shift potassium into cells by increasing pH (H+/K+ exchange), its efficacy is inconsistent and slower compared to insulin. It is generally reserved for patients with concomitant metabolic acidosis. **Clinical Pearls for NEET-PG:** * **Salbutamol (Nebulized):** Another shifting agent (β2 agonist) that also stimulates the Na+/K+-ATPase pump. It is often used as an adjunct to insulin. * **Definitive Treatment:** Hemodialysis is the most effective and fastest method for **removing** potassium from the body in patients with renal failure. * **ECG Progression:** Peaked T waves → PR prolongation → Loss of P wave → Widened QRS (Sine wave) → VF/Asystole.

Q: Which of the following is NOT a feature of type 4 A (Alport syndrome)?

Hypochloremic acidosis. The question refers to **Type 4 Renal Tubular Acidosis (RTA)**, also known as hyperkalemic RTA. The confusion in the question stem regarding "Type 4 A (Alport syndrome)" is a common nomenclature error; in the context of RTA, Type 4 refers to **Hypoaldosteronism** or resistance to aldosterone, not Alport syndrome (which is a collagen IV disorder). **1. Why "Hypochloremic acidosis" is the correct answer:** Type 4 RTA is characterized by **Hyperchloremic Metabolic Acidosis** (Normal Anion Gap Acidosis) [1]. In this condition, the lack of aldosterone effect leads to decreased potassium and hydrogen ion secretion in the distal tubule [1]. This results in the retention of chloride to maintain electrical neutrality, leading to high serum chloride levels, not low. Therefore, **Hypochloremic acidosis is incorrect** for Type 4 RTA. **2. Analysis of incorrect options:** * **Mild renal failure (A):** Type 4 RTA is frequently associated with mild to moderate chronic kidney disease (CKD), where the reduction in functioning nephrons contributes to impaired potassium excretion. * **Hyperkalemia (B):** This is the **hallmark** of Type 4 RTA [1]. Unlike Types 1 and 2 RTA (which cause hypokalemia), Type 4 is the only RTA characterized by high serum potassium due to aldosterone deficiency or resistance [1]. * **Occurs in diabetic nephropathy (D):** Diabetic nephropathy is the **most common cause** of Type 4 RTA. It often leads to a state of "Hyporeninemic Hypoaldosteronism" due to damage to the juxtaglomerular apparatus. **Clinical Pearls for NEET-PG:** * **Urine pH:** In Type 4 RTA, the urine pH is typically **< 5.5** (the distal acidification mechanism is intact, but the total acid excretion is low due to decreased ammonia production). * **Mnemonic:** Remember **"Type 4 is the only one with High K+"**. * **Common Causes:** Diabetes mellitus, NSAIDs, ACE inhibitors, and Heparin [1].

Q: A young adult normotensive patient presents with painless gross hematuria. What is the most likely diagnosis?

IgA nephropathy. **Explanation:** **IgA Nephropathy (Berger’s Disease)** is the most common cause of primary glomerulonephritis worldwide. The classic presentation is a young adult presenting with **episodic, painless gross hematuria**, often triggered by an upper respiratory tract infection (synpharyngitic hematuria) [1]. Unlike other nephritic syndromes, patients are frequently **normotensive** in the early stages and lack significant edema [1]. The underlying pathology involves the deposition of IgA in the glomerular mesangium [3]. **Why other options are incorrect:** * **Minimal Change Disease:** This is the most common cause of Nephrotic Syndrome in children. It typically presents with massive proteinuria and generalized edema (anasarca), not gross hematuria [2]. * **Crescentic Glomerulonephritis (RPGN):** This is a clinical emergency characterized by a rapid decline in renal function (rising creatinine) and is often associated with systemic symptoms, hypertension, and significant oliguria, rather than isolated painless hematuria [3]. * **Membranoproliferative Glomerulonephritis (MPGN):** This typically presents with a mixed nephritic-nephrotic picture. Patients often have persistent low complement levels (C3) and are more likely to be hypertensive [2]. **High-Yield Clinical Pearls for NEET-PG:** * **Synpharyngitic Hematuria:** Hematuria occurs simultaneously or within 1-2 days of an infection in IgA Nephropathy [1]. (Contrast this with **PSGN**, where hematuria occurs 1-3 weeks *after* a sore throat [2]). * **Diagnosis:** Gold standard is Renal Biopsy showing **mesangial IgA deposits** on Immunofluorescence [3]. * **Prognosis:** The most reliable predictor of poor prognosis is the degree of persistent proteinuria and hypertension. * **Association:** Often associated with Celiac disease and Henoch-Schönlein Purpura (HSP).

Q: All of the following are associated with polyuria except?

Rapidly progressive glomerulonephritis. **Explanation:** Polyuria is defined as a urine output exceeding **3 L/day** in adults. It occurs due to either an osmotic diuresis or a defect in water reabsorption. **Why Rapidly Progressive Glomerulonephritis (RPGN) is the correct answer:** RPGN is a clinical syndrome characterized by a rapid decline in GFR (usually >50% within weeks to months). The hallmark of RPGN is **oliguria** (urine output <400 ml/day) or even anuria, accompanied by an active urinary sediment (hematuria and red cell casts) [1]. Because the glomerular filtration rate drops precipitously, the kidneys cannot produce large volumes of urine, making polyuria clinically inconsistent with this diagnosis. **Analysis of Incorrect Options:** * **Diabetes Insipidus (DI):** This is the classic cause of water diuresis. Whether central (ADH deficiency) or nephrogenic (ADH resistance), the collecting ducts fail to reabsorb water, leading to massive volumes of dilute urine [2]. * **Diabetes Mellitus (DM):** This causes **osmotic diuresis**. High blood glucose levels exceed the renal threshold for reabsorption, leading to glucose in the proximal tubule. This glucose acts as an osmotically active particle, pulling water with it into the urine [2]. **NEET-PG High-Yield Pearls:** * **RPGN Histology:** The pathognomonic finding is **crescent formation** in Bowman’s space (composed of proliferating parietal epithelial cells and macrophages). * **Polyuria vs. Frequency:** Always distinguish polyuria (increased volume) from urinary frequency (increased number of voids with normal total volume). * **Other causes of Polyuria:** Hypercalcemia and Hypokalemia (both cause acquired nephrogenic DI), and the diuretic phase of Acute Tubular Necrosis (ATN). * **Oliguria Definition:** <400 ml/day; **Anuria:** <100 ml/day [1].

Question 1

In tubular necrosis, what is the typical ratio of urine to plasma creatinine?

Accepted Answer

Approximately 20

Answer

Approximately 40

Answer

Between 20-30

Answer

Between 30-40

Question 2

A 28-year-old man presents with lenticonus and end-stage renal disease (ESRD). His maternal uncle also died of a similar illness. What is the most likely diagnosis?

Accepted Answer

Alport syndrome

Answer

Autosomal recessive polycystic kidney disease

Answer

Autosomal dominant polycystic kidney disease

Answer

Oxalosis

Question 3

What is the cause of salt-losing nephropathy?

Accepted Answer

Interstitial nephropathy

Answer

Maintenance phase of acute tubular necrosis

Answer

Post-streptococcal glomerulonephritis

Answer

IgA nephropathy

Question 4

A patient presents with severe hyperkalemia and peaked T waves on ECG. What is the fastest method for shifting potassium intracellularly?

Accepted Answer

Insulin + glucose

Answer

Calcium gluconate IV

Answer

Oral resins

Answer

Sodium bicarbonate

Question 5

Which of the following is not true of acute Post-Streptococcal Glomerulonephritis (PSGN)?

Accepted Answer

PSGN following streptococcal skin infection will usually show positive Anti-Streptolysin O (ASLO) titre

Answer

Electron dense humps on glomerular basement membrane

Answer

Renal biopsy is indicated if prolonged hypocomplementemia persists beyond 2 months

Answer

C3 is low in the acute phase and returns to normal in 6-8 weeks

Question 6

Which of the following is NOT a feature of type 4 A (Alport syndrome)?

Accepted Answer

Hypochloremic acidosis

Answer

Mild renal failure

Answer

Hyperkalemia

Answer

Occurs in diabetic nephropathy

Question 7

A 45-year-old man presents with complaints of left-sided flank pain radiating into his groin. The pain began suddenly and has increased in intensity. He had a similar problem several years ago, but his symptoms resolved spontaneously. He denies fever, chills, nausea, or vomiting, and has had no diarrhea or difficulty urinating. Physical examination is remarkable for tenderness along the left flank and into the groin. A urinalysis reveals microscopic hematuria without casts. Serum chemistry reveals: Sodium: 143 mEq/L, Potassium: 2.4 mEq/L, Bicarbonate: 17 mEq/L, Chloride: 115 mEq/L, Blood urea nitrogen: 12 mg/dL, Creatinine: 1.0 mg/dL, Glucose: 85 mg/dL. Which of the following represents this patient's anion gap?

Accepted Answer

13.4 mEq/L

Answer

3.4 mEq/L

Answer

8.4 mEq/L

Answer

21.4 mEq/L

Question 8

Increased anion gap acidosis is seen in which of the following conditions?

Accepted Answer

Alcoholic ketoacidosis

Answer

Acute renal failure

Answer

Diabetic ketoacidosis

Answer

Ethylene glycol poisoning

Question 9

A young adult normotensive patient presents with painless gross hematuria. What is the most likely diagnosis?

Accepted Answer

IgA nephropathy

Answer

Minimal change disease

Answer

Crescentic glomerulonephritis

Answer

Membranoproliferative glomerulonephritis

Question 10

All of the following are associated with polyuria except?

Accepted Answer

Rapidly progressive glomerulonephritis

Answer

Diabetes insipidus

Answer

Diabetes mellitus

Nephrology — MCQs

Nephrology — MCQs

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