Nephrology Practice Questions

Q: According to the RIFLE criteria, what defines acute kidney injury?

Urine output 12 hours. The **RIFLE criteria** (Risk, Injury, Failure, Loss, and End-stage renal disease) were developed by the ADQI group to standardize the definition of Acute Kidney Injury (AKI). The classification is based on two parameters: Serum Creatinine (SCr)/GFR and Urine Output (UO). [1] ### **Explanation of the Correct Option** **Option B** is correct because, under the RIFLE criteria, the **"Injury"** stage is defined by: * **Creatinine:** 2-fold increase in SCr or GFR decrease > 50%. * **Urine Output:** 12 hours**. ### **Analysis of Incorrect Options** * **Option A:** 6 hours (not 8) defines the **"Risk"** stage. * **Option C:** 24 hours defines the **"Failure"** stage. * **Option D:** Anuria for **> 12 hours** also defines the **"Failure"** stage. ### **High-Yield NEET-PG Clinical Pearls** 1. **RIFLE vs. AKIN:** The AKIN (Acute Kidney Injury Network) criteria later modified this, defining AKI as a SCr increase of ≥ 0.3 mg/dL within 48 hours or a 1.5-fold increase from baseline. [1] 2. **The "L" and "E" in RIFLE:** * **Loss:** Persistent ARF = complete loss of kidney function > 4 weeks. * **ESRD:** End-stage renal disease > 3 months. 3. **Sensitivity:** The UO criteria are generally more sensitive but less specific than creatinine changes for early detection of AKI. 4. **KDIGO:** Currently, the KDIGO criteria are the most widely used in clinical practice, combining elements of both RIFLE and AKIN.

Q: Urine analysis of a patient with haematuria and hypercalciuria is most likely to reveal which of the following?

Isomorphic RBCs. ### Explanation The presence of **haematuria and hypercalciuria** in a patient typically points toward a **non-glomerular** cause of bleeding [1]. Hypercalciuria can cause irritation or micro-calculi formation in the renal pelvis or collecting system, leading to "urological" or extra-glomerular bleeding [2]. **1. Why Isomorphic RBCs is correct:** In extra-glomerular bleeding (e.g., stones, malignancy, or hypercalciuria-induced irritation), the red blood cells do not pass through the glomerular basement membrane [1]. Consequently, they maintain their normal size and biconcave shape. These are termed **isomorphic RBCs**. In contrast, glomerular bleeding causes RBCs to become "dysmorphic" (e.g., acanthocytes) due to mechanical trauma and osmotic shifts during their passage through the nephron. **2. Why other options are incorrect:** * **RBC Casts:** These are pathognomonic for **glomerular disease** (e.g., Glomerulonephritis). Casts form in the distal convoluted tubule when RBCs are trapped in a Tamm-Horsfall protein matrix. * **Nephrotic range proteinuria:** This indicates severe glomerular basement membrane damage (e.g., Minimal Change Disease, FSGS). Hypercalciuria-related haematuria is typically associated with minimal or no proteinuria [1]. * **Eosinophiluria:** This is a classic marker for **Acute Interstitial Nephritis (AIN)**, often drug-induced (e.g., NSAIDs, Penicillins), not hypercalciuria. **Clinical Pearls for NEET-PG:** * **Acanthocytes (G1 cells):** If >5% of total urinary RBCs are acanthocytes, it is highly specific for glomerular haematuria. * **Hypercalciuria:** Defined as >4 mg/kg/day of calcium excretion. It is the most common metabolic abnormality in children with unexplained isolated haematuria. * **Rule of Thumb:** Glomerular bleeding = Dysmorphic RBCs + RBC Casts + Significant Proteinuria. Extra-glomerular bleeding = Isomorphic RBCs + No Casts + Minimal Proteinuria [1].

Q: Microalbuminuria is defined as:

0.03-0.3 g of 24-hour urine albumin. **Explanation:** **Microalbuminuria** (now clinically referred to as **Moderately Increased Albuminuria**) is a critical marker for early-stage diabetic nephropathy and cardiovascular risk [1]. It represents a level of albumin excretion that is higher than normal but below the detection limit of a standard urine dipstick [1]. 1. **Why Option C is Correct:** The standard definition of microalbuminuria is an albumin excretion rate of **30–300 mg/day** (24-hour collection). Converting milligrams to grams, this equals **0.03–0.3 g of albumin**. It is essential to distinguish between *total protein* and *albumin*; microalbuminuria specifically measures the latter [3]. 2. **Analysis of Incorrect Options:** * **Option A (0.3–0.5 g protein):** This range exceeds the threshold for microalbuminuria and refers to "Macroalbuminuria" or overt proteinuria [3]. * **Option B (0.03–0.3 g protein):** This is incorrect because it specifies "protein." Total protein includes globulins and Tamm-Horsfall proteins; microalbuminuria is specific to albumin [2]. * **Option D (> 2.5 g protein):** This range approaches the **Nephrotic range proteinuria** (> 3.5 g/day), indicating severe glomerular damage. **High-Yield Clinical Pearls for NEET-PG:** * **Albumin-to-Creatinine Ratio (ACR):** In a spot urine sample, microalbuminuria is defined as an ACR of **30–300 mg/g**. * **Gold Standard:** The 24-hour urine collection remains the gold standard, but ACR is preferred for screening due to convenience. * **Clinical Significance:** It is the earliest clinical sign of diabetic nephropathy [3]. At this stage, the damage is potentially **reversible** with strict glycemic control and ACE inhibitors/ARBs. * **Diagnosis:** To confirm microalbuminuria, 2 out of 3 specimens collected over a 3-to-6-month period should be elevated (as transient elevation can occur due to exercise, fever, or CHF).

Q: Nephrocalcinosis is seen in all except:

Medullary cystic kidney disease. **Explanation:** Nephrocalcinosis refers to the generalized deposition of calcium salts within the renal parenchyma (medulla or cortex) [1]. To solve this question, one must distinguish between conditions that cause hypercalcemia/hypercalciuria and those that cause structural cysts. **Why Medullary Cystic Kidney Disease (MCKD) is the correct answer:** MCKD (now often classified under Autosomal Dominant Tubulointerstitial Kidney Disease) is characterized by the formation of cysts at the corticomedullary junction, tubular atrophy, and interstitial fibrosis [1]. While it involves the medulla, it **does not** typically lead to calcium deposition. In contrast, **Medullary Sponge Kidney** is a classic cause of nephrocalcinosis; students often confuse these two distinct entities [1]. **Analysis of Incorrect Options:** * **Sarcoidosis:** Causes increased production of 1,25-dihydroxyvitamin D by macrophages in granulomas, leading to hypercalcemia and hypercalciuria, which results in calcium deposition. * **Distal Renal Tubular Acidosis (Type 1 RTA):** This is the most common cause of medullary nephrocalcinosis [1]. The alkaline urine, hypocitraturia (citrate normally inhibits stone formation), and systemic acidosis leading to bone resorption create the perfect environment for calcium phosphate deposition. * **Milk Alkali Syndrome:** Excessive intake of calcium and absorbable alkali leads to hypercalcemia and metabolic alkalosis, directly causing metastatic calcification in the kidneys. **NEET-PG High-Yield Pearls:** * **Most common cause of Medullary Nephrocalcinosis:** Distal RTA (Type 1) [1]. * **Cortical Nephrocalcinosis:** Classically seen in Acute Tubular Necrosis (ATN), Chronic Glomerulonephritis, and Alport Syndrome [1]. * **Medullary Sponge Kidney vs. MCKD:** Remember, "Sponge" collects calcium (nephrocalcinosis), while "Cystic" (MCKD) leads to small kidneys and renal failure without calcification [1].

Q: A patient presents with sudden onset headache and loss of consciousness. Examination reveals renal cysts and evidence of subarachnoid hemorrhage, consistent with a berry aneurysm. What is the most likely diagnosis considering these findings?

Autosomal Dominant Polycystic Kidney Disease (ADPKD). **Explanation:** The clinical presentation of **renal cysts** associated with a **subarachnoid hemorrhage (SAH)** due to a **berry aneurysm** is a classic triad for **Autosomal Dominant Polycystic Kidney Disease (ADPKD)** [1]. **1. Why ADPKD is Correct:** ADPKD is a multisystemic disorder caused by mutations in the *PKD1* (85%) or *PKD2* (15%) genes [1]. While the hallmark is the development of bilateral renal cysts leading to end-stage renal disease, it has significant extra-renal manifestations. The most life-threatening extra-renal complication is **intracranial "berry" aneurysms**, typically located in the Circle of Willis [1]. Rupture of these aneurysms leads to sudden onset "thunderclap" headache and loss of consciousness (SAH) [2]. **2. Why Incorrect Options are Wrong:** * **Haemangioma of the liver:** While liver cysts are the most common extra-renal manifestation of ADPKD, a haemangioma is a vascular tumor and is not specifically associated with renal cysts or berry aneurysms. * **Meningioma:** This is a benign tumor of the meninges. It does not correlate with renal cystic disease or the acute presentation of a ruptured aneurysm. * **Head injury:** While trauma can cause intracranial hemorrhage, it does not explain the presence of pre-existing renal cysts [3]. **3. NEET-PG High-Yield Pearls:** * **Most common extra-renal site:** Liver (Hepatic cysts). * **Most common cause of death:** Cardiovascular disease (Hypertension/LVH). * **Cardiac association:** Mitral Valve Prolapse (MVP). * **Other associations:** Diverticulosis, seminal vesicle cysts, and pancreatic cysts. * **Screening:** MRA is recommended for berry aneurysms only if there is a positive family history of SAH or in high-risk occupations (e.g., pilots).

Q: Which of the following conditions is associated with normal anion gap acidosis?

Hyperchloremic acidosis. **Explanation:** Metabolic acidosis is classified based on the **Anion Gap (AG)**, calculated as: $AG = [Na^+] - ([Cl^-] + [HCO_3^-])$. The normal range is 8–12 mEq/L. **Why Hyperchloremic Acidosis is correct:** In **Normal Anion Gap Metabolic Acidosis (NAGMA)**, the loss of bicarbonate ($HCO_3^-$) is balanced by a reciprocal increase in serum chloride ($Cl^-$) to maintain electroneutrality. Because the sum of chloride and bicarbonate remains constant, the anion gap does not change. This is why NAGMA is synonymous with **Hyperchloremic Acidosis**. Common causes include diarrhea (GI loss of $HCO_3^-$) and Renal Tubular Acidosis (RTA). **Why the other options are incorrect:** * **Lactic Acidosis (A), Ketoacidosis (B), and Methanol Poisoning (C):** These are all causes of **High Anion Gap Metabolic Acidosis (HAGMA)**. In these conditions, metabolic acids (lactate, ketones, or formic acid) dissociate, adding "unmeasured anions" to the blood. These anions replace bicarbonate without increasing chloride, thus widening the gap. **High-Yield Clinical Pearls for NEET-PG:** * **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, Carbonic anhydrase inhibitors, Adrenal insufficiency, Renal tubular acidosis, Pancreatic fistula). * **Key Distinction:** Diarrhea is the most common cause of NAGMA, while DKA and Lactic acidosis are the most common causes of HAGMA.

Question 1

According to the RIFLE criteria, what defines acute kidney injury?

Accepted Answer

Urine output < 0.5 ml/kg/h for > 12 hours

Answer

Urine output < 0.5 ml/kg/h for > 8 hours

Answer

Urine output < 0.3 ml/kg/h for > 24 hours

Answer

Anuria for > 12 hours

Question 2

What is the treatment of choice in acute hyperkalemia that is life-threatening to cardiac myocytes?

Accepted Answer

Infusion of calcium gluconate

Answer

Oral resins

Answer

Intravenous infusion of insulin

Answer

Beta-blockers

Question 3

Urine analysis of a patient with haematuria and hypercalciuria is most likely to reveal which of the following?

Accepted Answer

Isomorphic RBCs

Answer

RBC casts

Answer

Nephrotic range proteinuria

Answer

Eosinophilluria

Question 4

Microalbuminuria is defined as:

Accepted Answer

0.03-0.3 g of 24-hour urine albumin

Answer

0.3-0.5 g of 24-hour urine protein

Answer

0.03-0.3 g of 24-hour urine protein

Answer

> 2.5 g of 24-hour urine protein

Question 5

Nephrocalcinosis is seen in all except:

Accepted Answer

Medullary cystic kidney disease

Answer

Sarcoidosis

Answer

Distal renal tubular acidosis

Answer

Milk alkali syndrome

Question 6

A 65-year-old woman is admitted to the hospital after a stroke resulting in left hemiparesis. She has no trouble swallowing and is on a full diet. One week later, on routine biochemistry, her sodium is 128 mEq/L and osmolality is 270 mOsm/kg. She has no symptoms and is euvolemic on clinical examination. Urine sodium is 40 mEq/L and urine osmolality is 450 mOsm/kg. For the above patient with hyponatremia, select the most likely diagnosis?

Accepted Answer

SIADH

Answer

Congestive heart failure (CHF)

Answer

Extrarenal sodium and fluid losses

Answer

Polydipsia

Question 7

A patient presents with sudden onset headache and loss of consciousness. Examination reveals renal cysts and evidence of subarachnoid hemorrhage, consistent with a berry aneurysm. What is the most likely diagnosis considering these findings?

Accepted Answer

Autosomal Dominant Polycystic Kidney Disease (ADPKD)

Answer

Haemangioma of the liver

Answer

Meningioma

Answer

Head injury

Question 8

A 20-year-old male with end-stage renal failure since age 13 has had progressive renal insufficiency, initially with episodes of painless hematuria. He also has progressive deafness. His brother suffers from a similar illness. What is the most likely diagnosis?

Accepted Answer

Alport syndrome

Answer

Henoch-Schönlein vasculitis

Answer

Familial lupus

Answer

Wegener's granulomatosis

Question 9

Which of the following conditions is associated with normal anion gap acidosis?

Accepted Answer

Hyperchloremic acidosis

Answer

Lactic acidosis

Answer

Ketoacidosis

Answer

Methanol poisoning

Question 10

Salt-losing nephritis is a feature of which of the following conditions?

Accepted Answer

Interstitial nephritis

Answer

Polycystic kidney disease

Answer

Lupus nephritis

Answer

Renal amyloidosis

Nephrology — MCQs

Nephrology — MCQs

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