Nephrology Practice Questions

Q: A 21-year-old female presents with a history of brown-colored urine that occurred approximately two months prior, lasting for about three days, following a cold. Currently, urinalysis shows blood with red cells and red cell casts. Further laboratory tests, including CBC, serum electrolytes, BUN, creatinine, glucose, ANAs, and serum complement levels (C3 and C4), are all within normal limits. Immunofluorescence examination of a renal biopsy reveals large, irregular deposits of IgA/C3 in the mesangium, with no linear staining pattern. What is the most likely diagnosis for this patient?

Berger's disease. **Explanation:** The clinical presentation is classic for **Berger’s disease (IgA Nephropathy)**, the most common primary glomerulonephritis worldwide. **Why Berger’s Disease is Correct:** 1. **Synpharyngitic Hematuria:** The history of brown-colored urine occurring shortly (within 1-2 days) after an upper respiratory tract infection ("a cold") is a hallmark [1]. This contrasts with Post-Streptococcal Glomerulonephritis (PSGN), which has a longer latent period (1-3 weeks) [1]. 2. **Normal Complements:** Unlike PSGN or Lupus Nephritis, serum C3 and C4 levels remain **normal** in IgA Nephropathy. 3. **Biopsy Findings:** Immunofluorescence showing **granular, irregular IgA and C3 deposits** restricted to the **mesangium** is the gold-standard diagnostic feature [1]. **Why Other Options are Incorrect:** * **Focal Segmental Glomerulosclerosis (FSGS):** Typically presents with nephrotic syndrome (heavy proteinuria). Biopsy shows segmental sclerosis in some glomeruli, not mesangial IgA deposits. * **Goodpasture’s Disease:** Characterized by anti-GBM antibodies. Immunofluorescence shows a **smooth, linear IgG staining** pattern along the glomerular basement membrane, not irregular mesangial IgA [1]. It often involves pulmonary hemorrhage. * **Lipoid Nephrosis (Minimal Change Disease):** The most common cause of nephrotic syndrome in children. Light microscopy and immunofluorescence are typically negative; diagnosis requires electron microscopy to see podocyte effacement. **High-Yield Pearls for NEET-PG:** * **Most common** primary GN worldwide: IgA Nephropathy. * **Henoch-Schönlein Purpura (HSP):** The systemic version of IgA nephropathy (presents with rash, joint pain, and abdominal pain). * **Prognosis:** Persistent proteinuria (>1g/day) and hypertension are the strongest predictors of progression to ESRD [1]. * **Association:** Often associated with Celiac disease and liver cirrhosis (decreased clearance of IgA complexes).

Q: What is the most important sign in hemodynamically significant renal artery stenosis?

Presence of collateral vessels. **Explanation:** The hallmark of **hemodynamically significant renal artery stenosis (RAS)** is the functional impact of the narrowing on renal perfusion. **1. Why "Presence of collateral vessels" is correct:** The development of collateral circulation (typically from the ureteral, adrenal, or capsular arteries) is the most definitive sign of a hemodynamically significant stenosis. Collaterals only form when the pressure gradient across the stenosis is high enough to recruit alternative pathways to maintain renal blood flow. This indicates that the stenosis is severe enough (usually >70-80% occlusion) to trigger a compensatory anatomical response. **2. Analysis of Incorrect Options:** * **Elevated renin level (Ipsilateral):** While a renin ratio of ≥ 1.5:1 between the affected and unaffected side suggests renovascular hypertension, it is a functional marker of ischemia rather than a definitive anatomical sign of significant stenosis. It can be influenced by medications (ACE inhibitors/Beta-blockers) [1]. * **Transstenotic pressure gradient:** A peak systolic pressure gradient of **≥ 20 mm Hg** (not 40 mm Hg) or a mean gradient of **> 10 mm Hg** is generally considered hemodynamically significant. Option C provides an incorrect threshold. * **Decrease in renal size:** While a difference in kidney size (>1.5 cm) is a common finding in chronic RAS, it is a non-specific sign of renal atrophy and can occur in various parenchymal diseases [1]. **Clinical Pearls for NEET-PG:** * **Gold Standard Investigation:** Digital Subtraction Angiography (DSA). * **Initial Screening Tool:** Duplex Doppler Ultrasound (look for "Tardus Parvus" pulse). * **Classic Presentation:** Resistant hypertension, flash pulmonary edema, or AKI after starting an ACE inhibitor [1]. * **Most common cause:** Atherosclerosis (elderly males); Fibromuscular Dysplasia (young females).

Q: What is the most common cause of renal artery stenosis in individuals above 50 years of age?

Atherosclerosis. **Explanation:** **1. Why Atherosclerosis is the correct answer:** Atherosclerosis is the most common cause of Renal Artery Stenosis (RAS) overall, accounting for approximately **90% of cases**. It primarily affects individuals **above 50 years of age**, particularly those with pre-existing risk factors such as smoking, diabetes, and hypertension. The lesion typically involves the **proximal one-third (ostial)** of the renal artery and is caused by the buildup of plaque that narrows the vessel lumen, leading to renovascular hypertension and ischemic nephropathy. **2. Why the other options are incorrect:** * **Fibromuscular Dysplasia (FMD):** This is the second most common cause of RAS but typically affects **younger females (20–40 years)**. It involves the distal two-thirds of the renal artery and presents with a characteristic "string of beads" appearance on angiography. * **Takayasu Arteritis:** Also known as "pulseless disease," this is a large-vessel vasculitis that can involve the renal artery ostium. However, it is much rarer than atherosclerosis and usually affects young Asian women under 40. * **Renal Cell Carcinoma (RCC):** While a tumor may compress the renal artery externally, it is not a primary cause of intrinsic renal artery stenosis. **3. Clinical Pearls for NEET-PG:** * **Gold Standard Investigation:** Digital Subtraction Angiography (DSA). * **Initial Screening Tool:** Duplex Ultrasound or CT Angiography. * **Classic Presentation:** Resistant hypertension, sudden onset of flash pulmonary edema, or an abdominal bruit. * **Treatment:** Medical management (ACE inhibitors/ARBs—*caution: contraindicated in bilateral RAS*), or Revascularization (PTRA with stenting) if medical therapy fails.

Q: What is the most common viral infection in kidney transplant recipients?

Cytomegalovirus (CMV). **Explanation:** **Cytomegalovirus (CMV)** is the most common clinically significant viral infection in kidney transplant recipients, typically occurring within the first 1–6 months post-transplant. The primary reason for its prevalence is the use of potent immunosuppressive therapy (like T-cell depleting agents), which triggers the reactivation of latent CMV residing in the donor organ or the recipient’s myeloid progenitor cells. CMV is a major cause of morbidity, leading to "CMV syndrome" (fever, malaise, leukopenia) or tissue-invasive disease (pneumonitis, hepatitis, and colitis). **Analysis of Incorrect Options:** * **BK Virus (BKV):** While BKV is a significant cause of graft dysfunction (BKV-associated nephropathy), it is less common than CMV. It typically presents later and is characterized by decoy cells in urine and viral inclusions in renal tubular cells. * **Herpes Simplex Virus (HSV):** HSV infections (mucocutaneous lesions) are common but usually occur early and are effectively managed or prevented with routine acyclovir prophylaxis. * **Hepatitis B Virus (HBV):** HBV is a chronic infection. While it can reactivate under immunosuppression, it is not the most common post-transplant viral infection due to rigorous pre-transplant screening and vaccination. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard Diagnosis:** Quantitative PCR for CMV DNA. * **Histopathology:** Characterized by **"Owl’s eye"** intranuclear inclusion bodies. * **Drug of Choice:** **Valganciclovir** (prophylaxis/mild disease) or **Ganciclovir** (treatment of choice for established disease). * **Risk Stratification:** The highest risk group is **D+/R-** (Seropositive Donor/Seronegative Recipient).

Q: For a patient with chronic renal failure (CRF), which of the following would be a specific indication to start dialysis?

Pericardial friction rub. ### Explanation In the management of Chronic Renal Failure (CRF), the decision to initiate dialysis is based on clinical manifestations of uremia rather than isolated laboratory values [1]. **Why Option D is Correct:** A **pericardial friction rub** is a diagnostic sign of **uremic pericarditis**, which is an absolute and urgent indication for dialysis. Uremic toxins cause inflammation of the pericardial sac; if left untreated, this can progress to pericardial effusion or life-threatening cardiac tamponade. Unlike other complications, uremic pericarditis does not respond to conservative management and requires immediate renal replacement therapy (RRT). **Why the Other Options are Incorrect:** * **Option A (BUN >90 mg/dl):** There is no absolute numerical threshold for BUN to start dialysis. While high levels (often >100 mg/dl) correlate with uremia, the patient’s clinical status (e.g., encephalopathy, vomiting) is more important than the number itself [1]. * **Option B (Urine output <10 ml/h):** Oliguria alone is not a specific indication for dialysis in CRF. Many patients with end-stage renal disease (ESRD) remain oliguric for months while being managed conservatively until other systemic complications arise. * **Option C (Hematocrit <30%):** Anemia is a common feature of CRF due to erythropoietin deficiency [1]. It is managed with Erythropoiesis-Stimulating Agents (ESAs) and iron supplementation, not dialysis. **Clinical Pearls for NEET-PG:** To remember the urgent indications for dialysis, use the mnemonic **AEIOU**: * **A** – Refractory Metabolic **A**cidosis (pH 6.5 mEq/L or ECG changes) * **I** – **I**ntoxications (e.g., Salicylates, Lithium, Methanol, Ethylene glycol) * **O** – Refractory Fluid **O**verload (Pulmonary edema) * **U** – **U**remic complications (**Pericarditis**, Encephalopathy, Asterixis, or bleeding diathesis) [1]

Q: Which of the following is NOT a feature of the maintenance phase of acute kidney injury?

Hypercalcemia. In the **maintenance phase** of Acute Kidney Injury (AKI), the Glomerular Filtration Rate (GFR) reaches its nadir, leading to the accumulation of metabolic waste and electrolyte imbalances. ### **Why Hypercalcemia is the Correct Answer** **Hypocalcemia**, not hypercalcemia, is the classic feature of the maintenance phase of AKI. This occurs due to two primary mechanisms: 1. **Reduced Vitamin D activation:** The damaged renal parenchyma cannot convert 25-hydroxyvitamin D into its active form (1,21-dihydroxyvitamin D). 2. **Hyperphosphatemia:** Elevated phosphate levels (due to decreased excretion) lead to the precipitation of calcium-phosphate salts in soft tissues, further lowering serum calcium [1]. *Note: Hypercalcemia is only seen during the **recovery (diuretic) phase** if there is mobilization of calcium from tissues or underlying rhabdomyolysis.* ### **Explanation of Incorrect Options** * **Hyperuricemia (A):** Reduced GFR leads to decreased renal clearance of uric acid, causing its accumulation. * **Hypermagnesemia (B):** Magnesium is primarily excreted by the kidneys. In AKI, impaired excretion leads to elevated levels, which can cause neuromuscular depression. * **Hypernatremia (C):** While hyponatremia is more common (due to water retention), hypernatremia can occur if there is a disproportionate loss of free water or excessive administration of sodium-containing fluids [1]. ### **High-Yield Clinical Pearls for NEET-PG** * **Most common electrolyte abnormality in AKI:** Hyperkalemia (due to decreased distal delivery of sodium and reduced K+ secretion). * **Metabolic state:** High anion gap metabolic acidosis (due to retention of organic acids like phosphates and sulfates). * **Recovery Phase:** Watch for **hypokalemia** and **hypomagnesemia** due to osmotic diuresis as the tubular function lags behind GFR recovery.

Question 1

A 21-year-old female presents with a history of brown-colored urine that occurred approximately two months prior, lasting for about three days, following a cold. Currently, urinalysis shows blood with red cells and red cell casts. Further laboratory tests, including CBC, serum electrolytes, BUN, creatinine, glucose, ANAs, and serum complement levels (C3 and C4), are all within normal limits. Immunofluorescence examination of a renal biopsy reveals large, irregular deposits of IgA/C3 in the mesangium, with no linear staining pattern. What is the most likely diagnosis for this patient?

Accepted Answer

Berger's disease

Answer

Focal segmental glomerulosclerosis

Answer

Goodpasture's disease

Answer

Lipoid nephrosis

Question 2

What is the most important sign in hemodynamically significant renal artery stenosis?

Accepted Answer

Presence of collateral vessels

Answer

Elevated renin level in ipsilateral renal vein

≥ 1.5 : 1

Answer

Transstenotic pressure gradient

≥ 40 mm Hg

Answer

Decrease in renal size

Question 3

What is the most common cause of renal artery stenosis in individuals above 50 years of age?

Accepted Answer

Atherosclerosis

Answer

Fibromuscular dysplasia (FMD)

Answer

Takayasu arteritis

Answer

Renal cell carcinoma (RCC)

Question 4

What is the most common viral infection in kidney transplant recipients?

Accepted Answer

Cytomegalovirus (CMV)

Answer

BK virus (BKV)

Answer

Herpes Simplex Virus (HSV)

Answer

Hepatitis B Virus (HBV)

Question 5

A 28-year-old female presents with suprapubic pain, urinary frequency, and dysuria. She also passed blood in her last voided urine approximately 30 minutes ago. Urinalysis demonstrates pyuria but no white cell casts. Physical examination reveals suprapubic tenderness on palpation. Which of the following is the likely diagnosis in this patient?

Accepted Answer

Cystitis

Answer

Acute pyelonephritis

Answer

Chronic pyelonephritis

Answer

Fanconi syndrome

Question 6

For a patient with chronic renal failure (CRF), which of the following would be a specific indication to start dialysis?

Accepted Answer

Pericardial friction rub

Answer

Blood urea nitrogen (BUN) rises to >90 mg/dl

Answer

Urine output falls to <10 ml/h

Answer

Hematocrit falls to <30%

Question 7

A patient presents with hematuria, proteinuria, and hypertension. Which of the following conditions is most likely associated with normal serum complement levels in this clinical scenario?

Accepted Answer

Henoch-Schonlein purpura

Answer

Mixed essential cryoglobulinemia

Answer

Hepatitis C-associated membranoproliferative glomerulonephritis

Answer

Diffuse proliferative lupus nephritis

Question 8

A 30-year-old man presents with generalized edema and hypertension. Urine examination shows sub-nephrotic proteinuria (< 2 gm) and microscopic hematuria. Serum complement levels are decreased and he is positive for anti-hepatitis C antibodies. What is the most likely diagnosis?

Accepted Answer

Membranoproliferative glomerulonephritis (MPGN)

Answer

Post-streptococcal Glomerulonephritis (PSGN)

Answer

Mixed cryoglobulinemia

Answer

Focal segmental Glomerulosclerosis (FSGS)

Question 9

Which of the following is NOT a feature of the maintenance phase of acute kidney injury?

Accepted Answer

Hypercalcemia

Answer

Hyperuricemia

Answer

Hypermagnesemia

Answer

Hypernatremia

Question 10

Which of the following statements is WRONG regarding adult polycystic kidney disease?

Accepted Answer

The presentation is bilateral

Answer

Kidneys are enlarged in size

Answer

Patients tend to have extra-renal congenital anomalies

Answer

Mitral valve prolapse may be present

Nephrology — MCQs

Nephrology — MCQs

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