Nephrology Practice Questions

Q: What is the most common cause of renal papillary necrosis?

Diabetes mellitus. **Explanation:** Renal Papillary Necrosis (RPN) is an ischemic infarct of the renal papillae, which are particularly vulnerable due to their relatively low blood supply and high osmolality. **Why Diabetes Mellitus is the Correct Answer:** While multiple conditions cause RPN, **Diabetes Mellitus** is statistically the **most common cause** (associated with over 50% of cases). The pathogenesis involves a combination of diabetic microangiopathy (ischemia) and a predisposition to recurrent urinary tract infections (pyelonephritis), which synergistically lead to papillary infarction. **Analysis of Incorrect Options:** * **Analgesic Nephropathy:** Historically a major cause due to phenacetin use, it is now less common. It occurs because NSAIDs inhibit prostaglandins, leading to medullary vasoconstriction and ischemia. * **Sickle Cell Disease/Trait:** A common cause in younger populations. Sickling of RBCs in the hypertonic, hypoxic environment of the renal medulla leads to micro-thrombosis and infarction. * **Chronic Pyelonephritis:** While severe infection can cause RPN, it is usually a secondary factor or occurs in the presence of obstruction or diabetes. **NEET-PG High-Yield Pearls:** * **Mnemonic for Causes (POSTCARDS):** **P**yelonephritis, **O**bstruction, **S**ickle cell, **T**uberculosis, **C**irrhosis, **A**nalgesics, **R**enal vein thrombosis, **D**iabetes mellitus, **S**ystemic vasculitis. * **Clinical Presentation:** Gross hematuria, flank pain (mimicking renal colic due to sloughed papillae obstructing the ureter), and "ring sign" on IVP (contrast surrounding a sloughed papilla). * **Key Distinction:** In Diabetes, RPN is often bilateral; in Sickle Cell, it can occur even in asymptomatic carriers (Sickle Cell Trait).

Q: Normal anion gap metabolic acidosis can occur in which of the following conditions?

Renal failure. **Explanation:** Metabolic acidosis is categorized based on the **Anion Gap (AG)**, calculated as $[Na^+] - ([Cl^-] + [HCO_3^-])$. **1. Why Renal Failure is Correct:** Renal failure is a unique cause that can present with both types of acidosis depending on the stage: * **Early Renal Failure (CKD Stages 1-4):** Often presents as **Normal Anion Gap Metabolic Acidosis (NAGMA)**. This occurs because the kidneys lose the ability to excrete ammonium ($NH_4^+$) and reabsorb bicarbonate, but the glomerular filtration rate (GFR) is still high enough to filter titratable acids (phosphates/sulfates). * **Advanced Renal Failure (ESRD/Stage 5):** As GFR drops significantly (<15-20 mL/min), the kidney can no longer filter unmeasured anions like phosphates, sulfates, and organic acids. These accumulate, leading to a **High Anion Gap Metabolic Acidosis (HAGMA)**. **2. Why Incorrect Options are Wrong:** * **Liver Failure, Severe Anemia, and Malignancy:** These conditions are classically associated with **Type A or Type B Lactic Acidosis** [1]. Lactic acid dissociates into lactate (an unmeasured anion), which increases the anion gap, resulting in **HAGMA**, not NAGMA. **3. NEET-PG High-Yield Pearls:** * **NAGMA Mnemonic (USED CARP):** **U**reterosigmoidostomy, **S**aline (Normal Saline infusion), **E**ndocrine (Addison’s), **D**iarrhea (most common cause), **C**arbonic anhydrase inhibitors (Acetazolamide), **A**mmonium chloride, **R**enal tubular acidosis (RTA), **P**ancreatic fistula [1]. * **HAGMA Mnemonic (MUDPILES):** **M**ethanol, **U**remia (Advanced Renal Failure), **D**KA, **P**ropylene glycol, **I**soniazid/Iron, **L**actic acidosis, **E**thylene glycol, **S**alicylates [1]. * **Key Distinction:** In NAGMA, the drop in $HCO_3^-$ is compensated by a rise in $Cl^-$, which is why it is also called **Hyperchloremic Metabolic Acidosis** [1].

Q: Which of the following statements about kidney injury molecule-1 (KIM-1) is false?

KIM-1 is abundantly expressed in distal tubular cells.. Kidney Injury Molecule-1 (KIM-1) is a type I transmembrane glycoprotein that has emerged as a highly specific and sensitive **biomarker for proximal tubular injury**. **1. Why Option B is the correct (False) statement:** KIM-1 is **not** expressed in distal tubular cells. In a healthy kidney, KIM-1 is virtually undetectable. However, following an ischemic or nephrotoxic insult, it is **markedly upregulated specifically in the proximal tubular epithelial cells**. It plays a role in tubular regeneration and acts as a phosphatidylserine receptor, transforming epithelial cells into "semi-professional" phagocytes to clear apoptotic debris. **2. Analysis of other options:** * **Option A:** KIM-1 is indeed a **novel biomarker** of AKI [1]. Unlike Serum Creatinine, which is a marker of function and rises late, KIM-1 is a marker of structural damage. * **Option C:** KIM-1 is highly stable and its ectodomain is shed into the lumen, allowing it to be **detected in the urine shortly after injury** (within hours), long before a rise in creatinine occurs. **High-Yield Clinical Pearls for NEET-PG:** * **Localization:** Proximal Tubule (High-yield: Contrast this with **NGAL**, which is expressed in both proximal and distal tubules). * **FDA Status:** KIM-1 is one of the few biomarkers qualified by the FDA for use in drug development to monitor nephrotoxicity. * **Predictive Value:** Higher urinary KIM-1 levels are associated with an increased risk of progressing to Chronic Kidney Disease (CKD). * **Other AKI Biomarkers:** NGAL (earliest), IL-18, L-FABP, and IGFBP-7 × TIMP-2 (Cell cycle arrest markers).

Q: Which of the following is seen in nephrotic syndrome?

Hypercoagulability. **Explanation:** Nephrotic syndrome is characterized by a triad of massive proteinuria, hypoalbuminemia, and generalized edema [1]. The correct answer is **Hypercoagulability**, which is a significant complication of this condition [1]. **1. Why Hypercoagulability is correct:** The loss of plasma proteins through the damaged glomerular basement membrane [2] includes natural anticoagulants, most notably **Antithrombin III (AT-III)**, Protein C, and Protein S. Simultaneously, the liver increases the synthesis of pro-coagulant factors (like Fibrinogen) and there is increased platelet aggregation. This imbalance shifts the hemostatic system toward a pro-thrombotic state, increasing the risk of deep vein thrombosis (DVT) and **Renal Vein Thrombosis (RVT)**, especially in Membranous Nephropathy [1]. **2. Why other options are incorrect:** * **A. Proteinuria less than 3.5 gm/day:** By definition, nephrotic-range proteinuria must be **>3.5 gm/24 hours** (in adults). Values below this are considered sub-nephrotic or characteristic of nephritic syndrome [2]. * **B. Hyperalbuminemia:** Nephrotic syndrome causes **Hypoalbuminemia** (<3 g/dL) due to massive urinary loss and catabolism of albumin in the proximal tubule [1]. * **C. Hypertension:** While hypertension can occur in some types of nephrotic syndrome (like FSGS), it is a classic hallmark of **Nephritic Syndrome** [2]. Nephrotic syndrome is primarily defined by metabolic and protein disturbances rather than inflammatory hematuria and hypertension. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause of RVT:** Membranous Nephropathy. * **Hyperlipidemia:** Seen in nephrotic syndrome due to compensatory hepatic synthesis of lipoproteins (LDL/VLDL) in response to low oncotic pressure [1]. * **Infection Risk:** Patients are prone to infections (e.g., *S. pneumoniae*) due to the loss of **Immunoglobulins (IgG)** and Complement factors in urine.

Question 1

A patient being treated for leukemia develops unilateral flank pain. Radiologic studies demonstrate a dilated renal pelvis and dilation of the upper one-third of the corresponding ureter. A stone with which of the following compositions is most likely causing this patient's problems?

Accepted Answer

Uric acid

Answer

Calcium salts

Answer

Cholesterol

Answer

Cystine

Question 2

All of the following are true about Bartter syndrome except?

Accepted Answer

Mineralocorticoid antagonists can be used.

Answer

Urinary calcium is increased.

Answer

Hypokalemic alkalosis is present.

Answer

Blood pressure is normal.

Question 3

A 24-year-old man has a urine analysis that is positive for blood. The microscopic examination of the urine is negative for casts or red blood cells. Which of the following is the most likely diagnosis?

Accepted Answer

Myoglobinuria

Answer

Hematuria

Answer

Nephritic syndrome

Answer

Renal cell carcinoma

Question 4

What is the most common cause of renal papillary necrosis?

Accepted Answer

Diabetes mellitus

Answer

Analgesic nephropathy

Answer

Sickle cell disease

Answer

Chronic pyelonephritis

Question 5

Which one of the following infections is typically seen one month after renal transplantation?

Accepted Answer

Cytomegalovirus

Answer

Varicella-zoster virus (Chickenpox)

Answer

Coxsackie virus

Answer

Epstein-Barr virus

Question 6

Normal anion gap metabolic acidosis can occur in which of the following conditions?

Accepted Answer

Renal failure

Answer

Liver failure

Answer

Severe anemia

Answer

Malignancy

Question 7

Which of the following statements about kidney injury molecule-1 (KIM-1) is false?

Accepted Answer

KIM-1 is abundantly expressed in distal tubular cells.

Answer

KIM-1 is a novel biomarker of acute kidney injury (AKI).

Answer

KIM-1 can be detected shortly after ischemic injury in the urine.

Answer

All the above statements are false.

Question 8

Which of the following is seen in nephrotic syndrome?

Accepted Answer

Hypercoagulability

Answer

Proteinuria less than 3.5 gm/day

Answer

Hyperalbuminemia

Answer

Hypertension

Question 9

Low complement levels are seen in which of the following conditions?

Accepted Answer

Post-streptococcal glomerulonephritis (PSGN)

Answer

Membranoproliferative glomerulonephritis (MPGN)

Answer

Goodpasture's syndrome

Answer

Wegener's granulomatosis

Question 10

Which of the following statements is NOT true regarding dialysis dementia syndrome?

Accepted Answer

Seizures and frank psychosis are early symptoms of the disease.

Answer

Presenting symptoms include dysarthria, apraxia, and slurred speech.

Answer

Aluminum chelation with deferoxamine is helpful in improving symptoms.

Answer

Its incidence has decreased with the use of aluminum-free water for dialysis.

Nephrology — MCQs

Nephrology — MCQs

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