Nephrology Practice Questions

Q: Signs and symptoms of renal failure first appear when renal function deteriorates by more than:

60%. **Explanation:** The kidneys possess a remarkable functional reserve, meaning they can maintain homeostasis even after significant nephron loss. Clinical signs and symptoms of renal failure typically do not manifest until the **Glomerular Filtration Rate (GFR) falls below 40-50% of normal**. This corresponds to a functional deterioration of **more than 60%**. [1] 1. **Why 60% is correct:** In the stages of Chronic Kidney Disease (CKD), the initial loss of nephrons leads to compensatory hypertrophy of the remaining functional units [1]. It is only when approximately **60-75% of renal function is lost** (Stage 3 CKD) that patients begin to develop biochemical abnormalities (azotemia) and clinical symptoms like anemia, hypertension, and nocturia. 2. **Why other options are incorrect:** * **20% & 40%:** At these levels of deterioration, the patient is usually asymptomatic [1]. The remaining nephrons compensate effectively, and serum creatinine may still be within the normal range (the "creatinine-blind" area). * **80%:** By the time 80% of function is lost, the patient is in advanced renal failure (Stage 4). Symptoms are already well-established and severe. **High-Yield NEET-PG Pearls:** * **Renal Reserve:** The ability of the kidney to increase GFR in response to physiological stimuli (e.g., a high protein meal). This reserve is lost early in renal disease. * **Azotemia vs. Uremia:** Azotemia is the biochemical finding of elevated nitrogenous wastes; Uremia is the clinical syndrome resulting from advanced renal failure [1]. * **First Sign:** Often, the earliest clinical sign of decreasing renal function is **isosthenuria** (the inability to concentrate or dilute urine, fixed at a specific gravity of ~1.010). * **Creatinine Trend:** Serum creatinine does not rise significantly above the normal range until the GFR has decreased by at least 50%.

Q: Hyperkalemia without ECG changes may be treated with all of the following except?

Calcium gluconate. ### Explanation The management of hyperkalemia is divided into three strategies: stabilizing the cardiac membrane, shifting potassium into cells, and removing potassium from the body [1]. **1. Why Calcium Gluconate is the Correct Answer:** Calcium gluconate (or calcium chloride) is used specifically to **stabilize the myocardial membrane** against the toxic effects of high potassium. It does not lower the serum potassium levels [1]. In clinical practice, calcium is indicated only when there are **ECG changes** (e.g., peaked T-waves, widened QRS) or severe hyperkalemia (>6.5 mEq/L). If a patient has hyperkalemia **without** ECG changes, calcium gluconate is not indicated as there is no immediate cardiac instability to counteract [1]. **2. Analysis of Incorrect Options (Potassium-Shifting Agents):** These agents are used to lower serum potassium levels by shifting it from the extracellular to the intracellular compartment [2]: * **Insulin with Dextrose:** The most reliable method to shift potassium into cells via the Na+/K+-ATPase pump. * **Salbutamol (Beta-2 Agonists):** Stimulates the Na+/K+-ATPase pump to promote intracellular potassium uptake. * **Sodium Bicarbonate:** Useful primarily in patients with concomitant metabolic acidosis; it shifts potassium into cells in exchange for hydrogen ions [2]. **3. NEET-PG High-Yield Pearls:** * **First-line for ECG changes:** Calcium gluconate (acts within 1–3 minutes; duration 30–60 mins) [1]. * **Most definitive treatment:** Hemodialysis (removes potassium from the body). * **Potassium removal agents:** Loop diuretics (Furosemide), Cation exchange resins (Patiromer, Sodium polystyrene sulfonate). * **"Pseudohyperkalemia":** Always rule this out (caused by hemolysis during blood draw or thrombocytosis) before aggressive treatment if the patient is asymptomatic with a normal ECG.

Q: The finding of urine sodium concentration <20 mmol/L in hypovolemic hyponatremia implies:

Trauma. The core concept in evaluating hyponatremia is determining the **effective arterial blood volume (EABV)** and the kidney's response to it. [1], [2] **1. Why Trauma is correct:** In hypovolemic hyponatremia, the body has lost both water and sodium. If the loss is **extra-renal** (e.g., trauma with hemorrhage, burns, vomiting, or diarrhea), the kidneys function normally to compensate for the volume depletion. [2] The activation of the Renin-Angiotensin-Aldosterone System (RAAS) leads to maximal sodium reabsorption in the tubules to preserve volume. [3] Consequently, the **Urinary Sodium (UNa) drops to <20 mmol/L**. [2] In the context of trauma, blood loss or "third-spacing" triggers this intense renal sodium conservation. **2. Why other options are incorrect:** * **Salt-wasting nephropathy (A), Diuretic therapy (B), and Hypoaldosteronism (C):** These are all causes of **renal** sodium loss. [2] In these conditions, the defect lies within the kidney or the hormonal control of the kidney (lack of aldosterone). Despite being hypovolemic, the kidney cannot "hold onto" sodium, resulting in a **Urinary Sodium >20 mmol/L**. [2] **High-Yield Clinical Pearls for NEET-PG:** * **UNa 20 mmol/L:** Suggests renal losses (Diuretics, ACE inhibitors, Mineralocorticoid deficiency, or intrinsic renal disease). [2] * **Fractional Excretion of Sodium (FeNa):** In oliguric states, FeNa 2% suggests intrinsic renal damage (ATN). * **The "Rule of Thumb":** If the source of fluid loss is *not* the kidney, the UNa should be low. If the source of loss *is* the kidney, the UNa will be high. [2]

Q: A 30-year-old male with NIDDM has a blood pressure of 150/90 mmHg and persistent albuminuria in traces on urine examination. What is the most appropriate line of treatment?

Administering lisinopril and restricting sodium intake. ### Explanation **1. Why Option C is Correct:** The patient presents with **Diabetic Nephropathy (DN)**, characterized by persistent albuminuria and hypertension (150/90 mmHg). In patients with diabetes and albuminuria, the standard of care is the initiation of an **ACE inhibitor (e.g., Lisinopril)** or an ARB [1]. * **Mechanism:** ACE inhibitors reduce intraglomerular pressure by causing vasodilation of the **efferent arteriole**. This slows the progression of renal damage and reduces proteinuria [1]. * **Sodium Restriction:** Reducing salt intake is essential as it enhances the antiproteinuric and antihypertensive effects of ACE inhibitors. **2. Why Other Options are Incorrect:** * **Option A & B:** These are passive approaches. Diabetic nephropathy is a progressive condition [2]; "watchful waiting" allows irreversible glomerular scarring (Kimmelstiel-Wilson lesions) to occur [2]. Early intervention is mandatory to prevent progression to End-Stage Renal Disease (ESRD) [1]. * **Option D:** While sodium restriction is beneficial, it is insufficient as a monotherapy. It does not address the hemodynamic changes (efferent vasoconstriction) driven by the Renin-Angiotensin-Aldosterone System (RAAS) in diabetic kidneys. **3. Clinical Pearls for NEET-PG:** * **Earliest Sign:** Microalbuminuria (30–300 mg/day) is the earliest clinical sign of DN [3]. * **Target BP:** For diabetic patients with proteinuria, the target BP is generally **<130/80 mmHg**. * **Drug of Choice:** ACE inhibitors/ARBs are the first-line agents regardless of baseline BP if albuminuria is present [1]. * **Screening:** Type 1 DM patients should be screened 5 years after diagnosis; Type 2 DM patients should be screened **at the time of diagnosis** [3]. * **Contraindication:** Never combine ACE inhibitors and ARBs due to the risk of hyperkalemia and acute kidney injury.

Q: Which of the following values are suggestive of acute tubular necrosis?

Urine sodium > 40 meq/L. In Acute Tubular Necrosis (ATN), the primary pathology is structural damage to the tubular epithelial cells [1]. This leads to a loss of the kidney's ability to reabsorb sodium and concentrate urine [2]. **1. Why Option B is Correct:** In ATN, the damaged tubules cannot reabsorb sodium effectively. Consequently, a large amount of sodium is "wasted" into the urine, resulting in a **Urine Sodium > 40 mEq/L** and a Fractional Excretion of Sodium (FeNa) > 2%. **2. Why the other options are incorrect:** * **Option A (Urine Osmolality > 500):** This is characteristic of **Prerenal Azotemia**. In ATN, the tubules cannot concentrate urine, leading to dilute urine with an osmolality typically ** 20:1):** This ratio suggests **Prerenal Azotemia**, where slow flow in the nephron allows for excessive urea reabsorption [2]. In ATN, the ratio is usually normal or low (** 40):** High ratios indicate that the kidneys are successfully concentrating waste. In ATN, this ratio drops to ** 2% = ATN**. * **Exception:** FeNa can be < 1% in certain types of ATN, such as those induced by contrast dye or rhabdomyolysis (due to intense vasoconstriction).

Q: Autosomal dominant tubulointerstitial kidney disease (ADTKD) patients have a defect in which of the following genes?

MUC1. **Explanation:** **Autosomal Dominant Tubulointerstitial Kidney Disease (ADTKD)** is a group of rare genetic disorders characterized by progressive interstitial fibrosis, tubular atrophy, and eventual end-stage renal disease (ESRD). Unlike Polycystic Kidney Disease, ADTKD typically presents with a **bland urinary sediment** (no blood or protein) and small-to-normal-sized kidneys on ultrasound. * **Why Option A is Correct:** The most common genetic cause of ADTKD is a mutation in the **MUC1 gene** (encoding Mucin-1), specifically a cytosine insertion in a repeat region. This leads to the production of a truncated, toxic protein (MUC1-fs) that accumulates in the tubular epithelial cells, causing cellular death and fibrosis. Other genes associated with ADTKD include **UMOD** (Uromodulin), **REN** (Renin), and **HNF1B**. * **Why Other Options are Incorrect:** * **B. PKD1:** Mutations in *PKD1* (85%) or *PKD2* cause **Autosomal Dominant Polycystic Kidney Disease (ADPKD)**, characterized by large, bilateral renal cysts and nephromegaly [1]. * **C. BBS 1:** Mutations in *BBS* genes cause **Bardet-Biedl Syndrome**, a ciliopathy characterized by obesity, polydactyly, retinitis pigmentosa, and renal anomalies. * **D. NPHS1:** Mutations in *NPHS1* (encoding Nephrin) cause **Congenital Nephrotic Syndrome of the Finnish type**, presenting with massive proteinuria in infancy. **High-Yield Clinical Pearls for NEET-PG:** * **Key Presentation:** Family history of ESRD + Normal urine microscopy + Hyperuricemia/Gout (especially in *UMOD* and *REN* mutations). * **Diagnosis:** Often requires genetic testing as renal biopsy shows non-specific interstitial fibrosis. * **Differentiating Feature:** Unlike ADPKD, kidneys in ADTKD are **not enlarged** and lack significant macro-cysts [1].

Q: Painless haematuria is found in all of the following conditions EXCEPT:

Cystitis. **Explanation:** The clinical distinction between painful and painless haematuria is a high-yield concept in NEET-PG nephrology. **Why Cystitis is the correct answer:** Cystitis (inflammation of the bladder, usually due to infection) is classically associated with **painful haematuria**. The inflammatory process irritates the bladder mucosa and trigone, leading to symptoms of dysuria, urgency, and suprapubic pain. In contrast, the question asks for conditions that present with *painless* haematuria. [1] **Analysis of Incorrect Options:** * **Renal Carcinoma (RCC):** Classically presents with "painless total haematuria." While the classic triad includes flank pain and a mass, the bleeding itself is typically painless unless clots cause ureteric colic. * **Chronic Glomerulonephritis:** Glomerular bleeding is typically painless [1]. It is often microscopic but can be macroscopic (smoky/cola-colored urine) without associated physical pain [2]. * **Polycystic Kidney Disease (ADPKD):** While cyst rupture can cause acute pain, ADPKD frequently presents with bouts of asymptomatic, painless gross haematuria due to the stretching of overlying vessels. **Clinical Pearls for NEET-PG:** 1. **Rule of Thumb:** Painless gross haematuria in an elderly patient is **Malignancy** (RCC or Bladder Cancer) until proven otherwise. 2. **Painful Haematuria Causes:** Think "Stones and Infections" (Urolithiasis, Cystitis, Urethritis) [1]. 3. **Glomerular vs. Post-Glomerular:** Look for dysmorphic RBCs or RBC casts to confirm a glomerular source (like GN), which is almost always painless [2]. 4. **IgA Nephropathy:** The most common cause of recurrent painless macroscopic haematuria synpharyngitically (coinciding with URTI).

Question 1

Signs and symptoms of renal failure first appear when renal function deteriorates by more than:

Accepted Answer

60%

Answer

20%

Answer

40%

Answer

80%

Question 2

Hyperkalemia without ECG changes may be treated with all of the following except?

Accepted Answer

Calcium gluconate

Answer

Salbutamol

Answer

Sodium bicarbonate

Answer

Insulin with dextrose

Question 3

Increased IgA deposits are seen in which condition?

Accepted Answer

Henoch Schonlein Purpura

Answer

Minimal Change Glomerulonephritis

Answer

Chronic Pyelonephritis

Answer

Hemolytic Uremic Syndrome

Question 4

The finding of urine sodium concentration <20 mmol/L in hypovolemic hyponatremia implies:

Accepted Answer

Trauma

Answer

Salt-wasting nephropathy

Answer

Diuretic therapy

Answer

Hypoaldosteronism

Question 5

In which of the following conditions is the formation of a calcium-containing kidney stone NOT likely?

Accepted Answer

Lesch-Nyhan syndrome.

Answer

Parathyroid adenoma.

Answer

Multiple myeloma.

Answer

Sarcoidosis.

Question 6

A 30-year-old male with NIDDM has a blood pressure of 150/90 mmHg and persistent albuminuria in traces on urine examination. What is the most appropriate line of treatment?

Accepted Answer

Administering lisinopril and restricting sodium intake

Answer

No treatment

Answer

Regular urine examination and monitoring of blood sugar

Answer

Restricting sodium intake only

Question 7

Which of the following values are suggestive of acute tubular necrosis?

Accepted Answer

Urine sodium > 40 meq/L

Answer

Urine osmolality > 500 mosmol/L H2O

Answer

Blood urea nitrogen/plasma creatinine ratio > 20:1

Answer

Urine creatinine/plasma creatinine ratio > 40

Question 8

Autosomal dominant tubulointerstitial kidney disease (ADTKD) patients have a defect in which of the following genes?

Accepted Answer

MUC1

Answer

PKD1

Answer

BBS 1

Answer

NPHS1

Question 9

Painless haematuria is found in all of the following conditions EXCEPT:

Accepted Answer

Cystitis

Answer

Renal carcinoma

Answer

Chronic glomerulonephritis

Answer

Polycystic kidney disease

Question 10

A patient on periodic renal dialysis requires minor oral surgery. When is the optimal timing for the procedure?

Accepted Answer

One day after dialysis

Answer

One day before dialysis

Answer

On the day of dialysis

Answer

One week after dialysis

Nephrology — MCQs

Nephrology — MCQs

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