Nephrology Practice Questions

Q: Renal biopsy is indicated in all the following conditions except:

Kidney size less than 60% of normal. The decision to perform a renal biopsy depends on whether the histological findings will alter management and if the procedure is safe. **Why Option B is the Correct Answer:** Small kidney size (typically <8–9 cm or <60% of normal) is a **relative contraindication** to renal biopsy [1]. It indicates **Chronic Kidney Disease (CKD)** with irreversible fibrosis and scarring (end-stage renal disease). In such cases, the biopsy is unlikely to yield a specific diagnosis that changes treatment, and the procedure carries a significantly higher risk of complications, such as bleeding, due to the increased hardness and reduced vascularity of the fibrotic tissue. **Analysis of Incorrect Options:** * **Option A:** While CRF usually presents with small kidneys, if the **kidneys are normal-sized**, a biopsy is indicated to rule out reversible or specific systemic conditions like Amyloidosis, Diabetic Nephropathy, HIV-associated nephropathy, or Polycystic Kidney Disease. * **Option C:** Most glomerular diseases in adults (e.g., Nephrotic Syndrome) require a biopsy to differentiate between types (e.g., Minimal Change, FSGS, Membranous) and guide immunosuppressive therapy [2]. * **Option D:** Asymptomatic proteinuria (especially if >1g/day) is an indication for biopsy to detect early-stage glomerulonephritis or systemic diseases before significant renal function is lost [2]. **NEET-PG High-Yield Pearls:** * **Absolute Contraindications:** Uncorrected bleeding diathesis, uncontrolled hypertension, and an uncooperative patient. * **Relative Contraindications:** Solitary kidney (except transplants), small shrunken kidneys, and active renal infection (e.g., pyelonephritis). * **Most common complication:** Microscopic hematuria (common); Perinephric hematoma (most common significant complication). * **Key indication:** Unexplained Acute Kidney Injury (AKI) or rapidly progressive glomerulonephritis (RPGN) [3].

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

Alport Syndrome. ### Explanation **Correct Answer: D. Alport Syndrome** **Concept:** Alport Syndrome is a hereditary type IV collagen disorder caused by mutations in the genes encoding the $\alpha$-3, $\alpha$-4, or $\alpha$-5 chains of the glomerular basement membrane (GBM) [1]. The classic triad includes **hereditary nephritis** (progressing to ESRD), **sensorineural hearing loss**, and **ocular abnormalities**. The presence of **Anterior Lenticonus** (a conical protrusion of the lens surface) is considered **pathognomonic** for Alport Syndrome. The history of a maternal uncle dying from similar symptoms strongly suggests an **X-linked Dominant** inheritance pattern (the most common form, involving the *COL4A5* gene), where males are more severely affected. **Why other options are incorrect:** * **ARPKD & ADPKD:** While both cause renal failure, they typically present with bilateral enlarged cystic kidneys and hypertension. They do not cause anterior lenticonus or sensorineural deafness. * **Oxalosis (Primary Hyperoxaluria):** This leads to nephrocalcinosis and recurrent urolithiasis due to oxalate crystal deposition. It does not involve the specific ocular or basement membrane defects seen here. **High-Yield Clinical Pearls for NEET-PG:** * **Electron Microscopy (EM):** Shows a characteristic **"Basket-weave appearance"** due to irregular thinning and thickening of the GBM [1]. * **Ocular Findings:** Anterior lenticonus (most specific), macular flecks, and cataracts. * **Inheritance:** 80% are X-linked Dominant (*COL4A5*); others are Autosomal Recessive or Dominant (*COL4A3/A4*). * **Goodpasture Syndrome Connection:** Patients with Alport syndrome who undergo kidney transplantation may develop **Anti-GBM disease** in the graft because their immune system recognizes the normal type IV collagen in the donor kidney as foreign.

Q: Which of the following genetic abnormalities is associated with the development of hyperkalemia?

Autosomal dominant polycystic kidney disease. **Explanation:** The correct answer is **Autosomal dominant polycystic kidney disease (ADPKD)**. **Why ADPKD is correct:** ADPKD is a progressive genetic disorder characterized by the growth of numerous cysts in the kidneys. As these cysts enlarge, they replace functional renal parenchyma, leading to **Chronic Kidney Disease (CKD)**. Hyperkalemia is a hallmark complication of advanced CKD due to a reduced Glomerular Filtration Rate (GFR), impaired potassium secretion in the distal nephron, and often, a state of hyporeninemic hypoaldosteronism. **Why the other options are incorrect:** * **Liddle’s Syndrome:** This is a "pseudoaldosteronism" caused by a gain-of-function mutation in the ENaC channels. It leads to excessive sodium reabsorption and potassium wasting, resulting in **hypokalemia** and hypertension. * **Gitelman Syndrome:** A loss-of-function mutation in the NCCT (sodium-chloride cotransporter) in the distal convoluted tubule. It mimics thiazide diuretic use, leading to **hypokalemia**, metabolic alkalosis, and hypomagnesemia. * **11β-hydroxylase deficiency:** This form of Congenital Adrenal Hyperplasia (CAH) leads to an accumulation of 11-deoxycorticosterone (DOC), a potent mineralocorticoid. This causes sodium retention and **hypokalemia**, alongside hypertension and virilization. **High-Yield Clinical Pearls for NEET-PG:** * **Rule of Thumb:** Most genetic tubulopathies (Bartter, Gitelman, Liddle) cause **hypokalemia**. * **Hyperkalemic Genetic Conditions:** Think of **Gordon’s Syndrome** (Pseudohypoaldosteronism Type II) or **Pseudohypoaldosteronism Type I**. * **ADPKD Associations:** Look for extra-renal manifestations like berry aneurysms (Circle of Willis), hepatic cysts, and mitral valve prolapse. * **Potassium & ECG:** Remember that hyperkalemia presents with tall peaked T-waves, while hypokalemia presents with U-waves and flattened T-waves.

Q: Calciphylaxis is seen in Chronic Kidney Disease (CKD) patients due to which of the following factors?

Warfarin. **Explanation:** **Calciphylaxis**, also known as **Calcific Uremic Arteriolopathy (CUA)**, is a devastating syndrome of vascular calcification and skin necrosis primarily seen in patients with End-Stage Renal Disease (ESRD). **Why Warfarin is the correct answer:** Warfarin is a potent risk factor for calciphylaxis. The underlying mechanism involves the inhibition of **Matrix Gla Protein (MGP)**. MGP is a vitamin K-dependent protein that acts as a powerful local inhibitor of vascular calcification. By antagonizing Vitamin K, Warfarin prevents the carboxylation (activation) of MGP, leading to unchecked calcium deposition in the media of small dermo-hypodermal arteries. This results in ischemia, livedo reticularis, and painful necrotic ulcers. **Why the other options are incorrect:** * **Hypoparathyroidism:** Calciphylaxis is associated with **Hyperparathyroidism** (secondary or tertiary). High PTH levels increase calcium-phosphate products, promoting metastatic calcification [1]. * **Urinary phosphate wasting:** Calciphylaxis is driven by **Hyperphosphatemia** (phosphate retention), which is a hallmark of CKD [1]. Phosphate acts as a signaling molecule that transforms vascular smooth muscle cells into osteoblast-like cells. * **Tumoral calcinosis:** This is a distinct clinical entity characterized by massive periarticular calcium deposits. While it also involves phosphate metabolism (FGF-23 mutations), it is not the underlying cause of the systemic ischemic necrosis seen in calciphylaxis. **High-Yield Clinical Pearls for NEET-PG:** * **Diagnosis:** Gold standard is a **deep punch biopsy** showing medial calcification and intimal hyperplasia of small vessels. * **Risk Factors:** Female gender, obesity, diabetes, hypoalbuminemia, and use of calcium-based phosphate binders. * **Management:** Discontinue Warfarin, optimize phosphate control, and use **Sodium Thiosulfate** (which helps dissolve calcium deposits).

Q: Which of the following conditions can cause low urinary calcium?

Chronic glomerulonephritis/CKD. **Explanation:** **Why Chronic Glomerulonephritis/CKD is correct:** In Chronic Kidney Disease (CKD), low urinary calcium (hypocalciuria) occurs due to two primary mechanisms: 1. **Reduced GFR:** As the glomerular filtration rate declines, the total filtered load of calcium decreases. 2. **Vitamin D Deficiency:** The kidneys are responsible for the 1-alpha-hydroxylation of 25-hydroxyvitamin D into its active form, **1,25-dihydroxyvitamin D (Calcitriol)**. In CKD, this conversion is impaired [1, 2]. Low calcitriol levels lead to decreased intestinal calcium absorption, resulting in hypocalcemia and a subsequent reduction in the amount of calcium excreted in the urine [1]. **Analysis of Incorrect Options:** * **A. Renal Tubular Acidosis (RTA):** Distal RTA (Type 1) is a classic cause of **hypercalciuria**. Chronic metabolic acidosis leads to buffering of acid by the bone, releasing calcium. Furthermore, acidosis inhibits distal tubular calcium reabsorption. * **B. Cushing’s Syndrome:** Excess glucocorticoids promote bone resorption and inhibit renal tubular calcium reabsorption, leading to **hypercalciuria** and an increased risk of nephrolithiasis. * **C. Paget’s Disease:** This condition involves high bone turnover. While patients are often normocalcemic, periods of immobilization or high disease activity lead to increased bone resorption, resulting in **hypercalciuria**. **High-Yield NEET-PG Pearls:** * **Hypocalciuria** is also a hallmark of **Familial Hypocalciuric Hypercalcemia (FHH)** (due to a defect in the Calcium-Sensing Receptor) and **Thiazide diuretic** use. * **Hypercalciuria** is a major risk factor for calcium oxalate stones; it is commonly seen in **Sarcoidosis** (due to extra-renal Vitamin D production) and **Loop diuretic** use. * In CKD, the biochemical triad is: **Hypocalcemia, Hyperphosphatemia, and Secondary Hyperparathyroidism.** [1, 2]

Q: Which of the following are characteristic findings in hyperkalemia?

Serum level > 6.5 mEq/L. Hyperkalemia is defined as a serum potassium concentration exceeding the normal range (typically **3.5–5.0 mEq/L**). In the context of clinical examination and ECG changes, it is categorized by severity. **Explanation of the Correct Option:** * **Option B (Serum level > 6.5 mEq/L):** While hyperkalemia technically begins above 5.5 mEq/L, severe hyperkalemia is defined as levels **> 6.5 mEq/L**. At this concentration, the risk of life-threatening arrhythmias increases significantly, and classic ECG changes (like QRS widening) become prominent. In many standardized medical exams, "characteristic" findings or the threshold for aggressive intervention are often linked to this higher value. **Explanation of Incorrect Options:** * **Option A (Serum level > 5.5 mEq/L):** This represents mild hyperkalemia. While it is the diagnostic threshold, it is often asymptomatic and lacks the "characteristic" clinical urgency or ECG manifestations seen at higher levels. * **Option C (T wave inversion):** This is a feature of **hypokalemia** or myocardial ischemia. In hyperkalemia, the T waves do not invert; they become narrow and tall. * **Option D (Peaking of T wave):** While tall, "tented" T waves are the *earliest* sign of hyperkalemia, the question asks for characteristic findings in a context where Option B is marked correct, likely prioritizing the biochemical definition of severe hyperkalemia. **High-Yield Clinical Pearls for NEET-PG:** * **ECG Progression:** Tall tented T waves (earliest) → Prolonged PR interval → Loss of P wave → Widened QRS (Sine wave pattern) → Ventricular fibrillation/Asystole. * **Pseudohyperkalemia:** Often caused by hemolysis during blood draw or marked leukocytosis/thrombocytosis. * **Management:** "C-BIG-K" (Calcium gluconate for membrane stabilization, Bicarbonate/Insulin + Glucose for intracellular shift, Kayexalate/Dialysis for removal).

Q: A patient in the oliguric phase of renal failure is expected to have a 24-hour urine output less than which of the following values?

400ml. ### Explanation **Correct Option: B. 400ml** In clinical nephrology, **Oliguria** is defined as a urine output of less than **400 ml/day** (or <0.5 ml/kg/hour in adults) [1]. This threshold is physiologically significant because it represents the minimum amount of urine required to excrete the average daily load of metabolic waste products (solutes like urea and creatinine), assuming the kidneys are maximally concentrating the urine (approx. 1200 mOsm/L). When output falls below this level, solute accumulation occurs, leading to azotemia. **Analysis of Incorrect Options:** * **A. 200ml:** While 200ml is technically oliguric, it is not the standard diagnostic threshold. Urine output <100 ml/day is specifically defined as **Anuria** [1], which often suggests complete urinary tract obstruction, bilateral renal artery occlusion, or cortical necrosis. * **C. 800ml & D. 1000ml:** These values fall within the range of normal or "non-oliguric" urine output. Patients can still be in acute kidney injury (AKI) with these volumes; this is termed **Non-oliguric AKI** [2] (commonly seen in aminoglycoside toxicity or interstitial nephritis), which generally carries a better prognosis than oliguric AKI. **Clinical Pearls for NEET-PG:** * **Phases of AKI:** 1. Initiation phase, 2. Oliguric phase (maintenance), 3. Polyuric phase (recovery). * **Polyuric Phase:** During recovery, urine output can exceed 3–5 liters/day. The most common cause of death in this phase is **hypokalemia** and dehydration. * **Azotemia vs. Uremia:** Azotemia is the biochemical increase in nitrogenous waste; Uremia is the clinical syndrome resulting from that increase. * **Fractional Excretion of Sodium (FeNa):** In the oliguric phase of Prerenal AKI, FeNa is 2%.

Question 1

Renal biopsy is indicated in all the following conditions except:

Accepted Answer

Kidney size less than 60% of normal

Answer

Chronic renal failure with normal-sized kidneys

Answer

Glomerular disease in adults

Answer

Asymptomatic proteinuria

Question 2

A 28-year-old man presents with anterior lenticonus and end-stage renal disease. 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

Which of the following genetic abnormalities is associated with the development of hyperkalemia?

Accepted Answer

Autosomal dominant polycystic kidney disease

Answer

11b-hydroxylase deficiency

Answer

Liddle's syndrome

Answer

Gitelman syndrome

Question 4

Calciphylaxis is seen in Chronic Kidney Disease (CKD) patients due to which of the following factors?

Accepted Answer

Warfarin

Answer

Hypoparathyroidism

Answer

Urinary phosphate wasting

Answer

Tumoral calcinosis

Question 5

Which of the following is a characteristic feature of hepatorenal syndrome?

Accepted Answer

Urine sodium < 10 mEq/L

Answer

Normal renal histology

Answer

Renal function remains abnormal even after liver function improves

Answer

Proteinuria < 500 mg/day

Question 6

Which of the following conditions can cause low urinary calcium?

Accepted Answer

Chronic glomerulonephritis/CKD

Answer

Renal tubular acidosis

Answer

Cushing's syndrome

Answer

Paget's disease

Question 7

A 12-year-old boy with a history of deafness and recurrent hematuria presents with chronic kidney disease. The family history reveals the death of his maternal uncle due to a similar condition. A kidney biopsy shows normal light microscopy. What is the probable diagnosis?

Accepted Answer

Alport's syndrome

Answer

Goodpasture syndrome

Answer

Thin basement membrane disease

Answer

Post-streptococcal glomerulonephritis

Question 8

Which of the following are characteristic findings in hyperkalemia?

Accepted Answer

Serum level > 6.5 mEq/L

Answer

Serum level > 5.5 mEq/L

Answer

T wave inversion

Answer

Peaking of T wave

Question 9

A patient in the oliguric phase of renal failure is expected to have a 24-hour urine output less than which of the following values?

Accepted Answer

400ml

Answer

200ml

Answer

800ml

Answer

1000ml

Question 10

Urinary eosinophilia is a feature of?

Accepted Answer

Atheroembolic kidney disease

Answer

Renal vein thrombosis

Answer

Gaucher disease

Answer

Myeloma Kidney

Nephrology — MCQs

Nephrology — MCQs

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