Nephrology Practice Questions

Q: In chronic glomerulonephritis, what is the most significant urinary finding?

Fixed specific gravity. **Explanation:** In Chronic Glomerulonephritis (CGN), the progressive destruction of nephrons leads to a loss of the kidney's ability to concentrate or dilute urine [2]. This physiological state is known as **Isosthenuria**. **1. Why "Fixed Specific Gravity" is correct:** As chronic renal damage progresses, the renal tubules lose their responsiveness to ADH and their ability to maintain the medullary osmotic gradient. Consequently, the kidney can no longer modify the glomerular filtrate. The urine specific gravity becomes "fixed" at approximately **1.010**, which is identical to the specific gravity of plasma [3]. This is a hallmark of end-stage renal disease and significant tubular dysfunction. **2. Analysis of Incorrect Options:** * **Albuminuria:** While common in CGN, it is non-specific [1]. It occurs in various conditions like nephrotic syndrome, diabetes, and acute glomerulonephritis. It does not necessarily indicate the "chronic" or "fixed" nature of the disease as accurately as isosthenuria. * **Bacteriuria:** This indicates a Urinary Tract Infection (UTI), not a primary glomerular disease. * **Red Blood Cell (RBC) Casts:** These are the hallmark of **Acute Glomerulonephritis** (Nephritic Syndrome). While they may be seen in acute exacerbations of CGN, they are often absent in the late, sclerotic stages of the disease. **Clinical Pearls for NEET-PG:** * **Isosthenuria:** Specific gravity fixed at 1.010 [3]. * **Broad Casts:** Also known as "Renal Failure Casts," these are highly characteristic of chronic renal failure/CGN as they form in dilated, atrophic tubules. * **Small, shrunken kidneys** on ultrasound are the classic imaging finding for CGN (except in Diabetes, Amyloidosis, and Polycystic Kidney Disease).

Q: Which of the following conditions is not associated with an increased anion gap?

Proximal RTA. ### Explanation Metabolic acidosis is categorized based on the **Anion Gap (AG)**, calculated as $[Na^+] - ([Cl^-] + [HCO_3^-])$. The normal range is 8–12 mEq/L. **Why Proximal RTA is the correct answer:** Proximal Renal Tubular Acidosis (Type 2 RTA) is a **Normal Anion Gap Metabolic Acidosis (NAGMA)**, also known as hyperchloremic metabolic acidosis [1]. In this condition, the proximal tubule fails to reabsorb bicarbonate ($HCO_3^-$). To maintain electroneutrality as bicarbonate is lost, the kidneys retain Chloride ($Cl^-$). Since the increase in chloride offsets the decrease in bicarbonate, the anion gap remains unchanged. **Analysis of Incorrect Options (High Anion Gap Metabolic Acidosis - HAGMA):** * **Salicylate poisoning:** Aspirin overdose causes HAGMA due to the accumulation of salicylic acid and interference with the Krebs cycle, leading to organic acid buildup [1]. * **Ethylene glycol poisoning:** Metabolism of this antifreeze agent produces glycolic and oxalic acids, which contribute unmeasured anions to the blood. * **Lactic acidosis:** This is the most common cause of HAGMA, resulting from tissue hypoxia (Type A) or metabolic derangements (Type B), leading to the accumulation of lactate anions [1]. **NEET-PG High-Yield Pearls:** * **Mnemonic for HAGMA:** **MUDPILES** (Methanol, Uremia, DKA, Propylene glycol, Iron/INH, Lactic acidosis, Ethylene glycol, Salicylates). * **Mnemonic for NAGMA:** **USED CARP** (Ureterosigmoidostomy, Small bowel fistula, Extra chloride, Diarrhea, **RTA**, Pancreatic fistula). * **Key Distinction:** All RTAs (Type 1, 2, and 4) cause NAGMA [1]. If a question features RTA vs. toxins/shock, RTA is almost always the "normal gap" outlier.

Q: What type of RBC is typically seen in chronic renal failure?

Normocytic. **Explanation:** The hallmark of anemia in Chronic Renal Failure (CRF) is a **Normocytic Normochromic Anemia**. **Why Normocytic is Correct:** The primary cause of anemia in CRF is the **deficiency of Erythropoietin (EPO)** [2]. EPO is a glycoprotein hormone produced by the peritubular interstitial cells of the kidney [2], [3]. As renal parenchyma is lost, EPO production decreases, leading to reduced stimulation of the bone marrow to produce red blood cells [2]. Since the defect lies in the *quantity* of cells produced rather than the *quality* of hemoglobin synthesis or cell division, the resulting RBCs are normal in size (normocytic) and color (normochromic). **Why other options are incorrect:** * **Microcytic:** This is typically seen in Iron Deficiency Anemia (IDA). While CRF patients may develop IDA due to chronic blood loss (hemodialysis or GI bleeds) or functional iron deficiency (hepcidin-mediated), the classic, primary presentation of renal anemia remains normocytic [1]. * **Macrocytic:** This is characteristic of Vitamin B12 or Folate deficiency. While malnutrition can occur in uremic patients, it is not the standard hematological profile of renal failure itself. **High-Yield Clinical Pearls for NEET-PG:** * **Target Hemoglobin:** In patients on EPO therapy for CRF, the target Hb is usually **10–11.5 g/dL**. Aiming for normal levels (>13 g/dL) increases the risk of stroke and cardiovascular events (CHOIR and CREATE trials). * **Burr Cells (Echinocytes):** These are small, spiked RBCs often seen on the peripheral smear of uremic patients. * **Resistance to EPO:** The most common cause of a poor response to exogenous EPO in CRF patients is **Iron Deficiency** [1]. Always check ferritin and TSAT levels before starting EPO.

Q: The captopril test is used as a diagnostic test for?

Renovascular hypertension. The **Captopril Test** (specifically the Captopril Renography or Captopril-enhanced DTPA/MAG3 scan) is a classic diagnostic tool for **Renovascular Hypertension (RVH)**, most commonly caused by renal artery stenosis [1], [2]. **1. Why Renovascular Hypertension is correct:** In renal artery stenosis, the affected kidney experiences decreased perfusion pressure [1]. To maintain the Glomerular Filtration Rate (GFR), the kidney activates the Renin-Angiotensin-Aldosterone System (RAAS). Angiotensin II causes **vasoconstriction of the efferent arteriole**, which maintains intraglomerular pressure. When Captopril (an ACE inhibitor) is administered, it blocks the formation of Angiotensin II. This leads to **efferent arteriolar vasodilation**, causing a sharp drop in intraglomerular pressure and a significant **reduction in GFR** in the stenotic kidney. This functional drop is captured via radionuclide imaging (MAG3), confirming the diagnosis [2]. **2. Why other options are incorrect:** * **Postural Hypotension:** Diagnosed via the "Tilt Table Test" or by measuring blood pressure changes upon standing. * **Acute Congestive Heart Failure:** Diagnosed clinically and via NT-proBNP levels and Echocardiography. While ACE inhibitors are used for treatment, they are not used as a diagnostic "test." * **Myocardial Infarction:** Diagnosed via ECG changes and cardiac biomarkers (Troponin I/T) [3]. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard Diagnosis:** Renal Angiography remains the gold standard for RVH. * **Screening:** Duplex Doppler or CT/MR Angiography are now more commonly used than the Captopril test in modern practice [1], [4]. * **Clinical Clue:** Suspect RVH if a patient develops an acute rise in serum creatinine (>30%) after starting an ACE inhibitor or ARB. * **Physical Sign:** A continuous abdominal bruit is highly suggestive of renal artery stenosis [1].

Q: What is the typical blood flow rate used in a hemodialysis machine?

300-500 ml/min. **Explanation:** In hemodialysis, the **Blood Flow Rate (Qb)** is a critical determinant of solute clearance (Kt/V). To achieve adequate removal of urea and creatinine within a standard 3-to-4-hour session, a flow rate of **300–500 ml/min** is required [1]. This range is optimized to maximize the concentration gradient across the dialyzer membrane while remaining within the physiological limits of a well-functioning arteriovenous fistula (AVF) or graft. **Analysis of Options:** * **Option A (100-200 ml/min):** This rate is too slow for efficient adult dialysis. It is typically only used during the initiation of the very first dialysis session to prevent **Dialysis Disequilibrium Syndrome (DDS)** or in pediatric cases. * **Option C & D (700-1000+ ml/min):** These rates are physiologically unsustainable for most vascular accesses. High flow rates exceeding 600 ml/min significantly increase the risk of high-output cardiac failure and can cause excessive turbulence, leading to hemolysis or access stenosis. **NEET-PG High-Yield Pearls:** 1. **Dialysate Flow Rate (Qd):** Usually maintained at **500–800 ml/min** (typically 1.5 to 2 times the blood flow rate) to maintain a steep diffusion gradient. 2. **Vascular Access:** The "Gold Standard" is the **Brescia-Cimino fistula** (Radio-cephalic) [1]. 3. **Rule of 6s:** A mature fistula should have a diameter >6mm, be 600ml/min. 4. **Dialysis Disequilibrium Syndrome:** Caused by rapid removal of urea from the blood, leading to cerebral edema. Prevented by using lower blood flow rates (Option A) in the initial session.

Q: Alport syndrome is inherited as:

X-linked. **Explanation:** Alport Syndrome is a hereditary nephritis caused by mutations in the genes encoding **Type IV collagen**, which is a critical structural component of the glomerular basement membrane (GBM), cochlea, and lens [1]. **1. Why X-linked is Correct:** The most common mode of inheritance (approximately **85% of cases**) is **X-linked Dominant**, caused by a mutation in the **COL4A5** gene. Because it is X-linked, males are typically more severely affected, often progressing to end-stage renal disease (ESRD), while females (carriers) may present only with isolated hematuria. **2. Analysis of Incorrect Options:** * **Autosomal Recessive (D) & Autosomal Dominant (C):** While these forms do exist (due to mutations in *COL4A3* or *COL4A4*), they are significantly less common (approx. 15%). In the context of competitive exams like NEET-PG, if a single best answer is required, X-linked is the standard choice as it represents the vast majority of cases. * **Co-dominant (B):** This pattern is not associated with the inheritance of Type IV collagen disorders. **3. Clinical Pearls for NEET-PG:** * **Classic Triad:** Hereditary nephritis (hematuria/ESRD), Sensorineural hearing loss (high frequency), and Ocular defects. * **Pathognomonic Ocular Sign:** **Anterior Lenticonus** (conical protrusion of the lens). * **Electron Microscopy (High Yield):** Shows characteristic **"Basket-weave appearance"** due to irregular thinning and thickening of the GBM. * **Key Association:** Patients may develop Anti-GBM disease (Goodpasture-like syndrome) after receiving a kidney transplant [1].

Question 1

Which of the following are features of Rhabdomyolysis?

Accepted Answer

Myoglobinuria

Answer

Present with acute muscular weakness

Answer

Calf muscles commonly ruptured

Answer

Acute renal failure is most common

Question 2

Which of the following is seen in nephrotic syndrome?

Accepted Answer

Low lipid

Answer

Low serum calcium

Answer

Raised AT-III

Answer

Platelet activation

Question 3

In chronic glomerulonephritis, what is the most significant urinary finding?

Accepted Answer

Fixed specific gravity

Answer

Albuminuria

Answer

Bacteriuria

Answer

Red blood cell casts

Question 4

All of the following conditions can lead to chronic renal failure (CRF) except?

Accepted Answer

Post-streptococcal glomerulonephritis

Answer

Membranoproliferative glomerulonephritis

Answer

Minimal change disease

Answer

Focal glomerulosclerosis

Question 5

Which of the following conditions is not associated with an increased anion gap?

Accepted Answer

Proximal RTA

Answer

Salicylate poisoning

Answer

Ethylene glycol poisoning

Answer

Lactic acidosis

Question 6

What type of RBC is typically seen in chronic renal failure?

Accepted Answer

Normocytic

Answer

Microcytic

Answer

Macrocytic

Answer

None of the above

Question 7

The captopril test is used as a diagnostic test for?

Accepted Answer

Renovascular hypertension

Answer

Postural hypotension

Answer

Acute congestive heart failure

Answer

Myocardial infarction

Question 8

What is the typical blood flow rate used in a hemodialysis machine?

Accepted Answer

300-500 ml/min

Answer

100-200 ml/min

Answer

700-800 ml/min

Answer

>1000 ml/min

Question 9

Which of the following is false about adult polycystic kidney disease?

Accepted Answer

The most common cause of death is rupture of a berry aneurysm

Answer

Autosomal dominant inheritance

Answer

Associated with mitral valve prolapse

Answer

Cysts can be found in the liver, lungs, and pancreas

Question 10

Alport syndrome is inherited as:

Accepted Answer

X-linked

Answer

Co-dominant

Answer

Autosomal dominant

Answer

Autosomal recessive

Nephrology — MCQs

Nephrology — MCQs

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