Nephrology Practice Questions

Q: At what serum potassium level does a sine wave pattern typically appear on an ECG?

> 8 mEq/dl. ### Explanation Hyperkalemia is a life-threatening electrolyte abnormality that causes progressive changes in cardiac conduction. The correct answer is **> 8 mEq/L** because the "sine wave" pattern represents the final stage of intraventricular conduction delay before cardiac arrest. **The Progression of ECG Changes:** 1. **5.5 – 6.5 mEq/L:** The earliest sign is **tall, peaked T-waves** (narrow base, "tent-shaped") due to rapid repolarization [1]. 2. **6.5 – 8.0 mEq/L:** As potassium rises, the atrial myocardium becomes paralyzed, leading to **loss of P-waves** (atrial standstill) [1]. Simultaneously, the QRS complex begins to widen [1]. 3. **> 8.0 mEq/L:** Extreme widening of the QRS complex causes it to merge with the T-wave. This creates a smooth, undulating, biphasic rhythm known as the **sine wave pattern**. If untreated, this progresses rapidly to ventricular fibrillation or asystole [1]. **Analysis of Incorrect Options:** * **Option A (> 6 mEq/L):** Associated with peaked T-waves and initial PR interval prolongation, but not sine waves. * **Option B (> 7 mEq/L):** Typically characterized by the disappearance of P-waves and significant QRS widening, but the distinct sine wave morphology usually requires higher levels [2]. * **Option D (> 10 mEq/L):** While a sine wave will certainly be present, this level is often incompatible with life; the pattern typically manifests earlier, around the 8–9 mEq/L range. **High-Yield Clinical Pearls for NEET-PG:** * **Treatment Priority:** The first step in management when ECG changes are present is **Calcium Gluconate** (10 ml of 10% solution) to stabilize the myocardial membrane [2]. It does *not* lower serum potassium. * **Pseudohyperkalemia:** Always rule out hemolysis during blood collection or thrombocytosis/leukocytosis if ECG is normal despite high lab values. * **Causative Drugs:** ACE inhibitors, ARBs, Spironolactone, and NSAIDs are common culprits in boards.

Q: HIV-induced nephropathy is more common in which of the following subsets of HIV patients?

Intravenous drug abusers. **Explanation:** **HIV-Associated Nephropathy (HIVAN)** is a classic form of renal involvement in HIV patients, characterized histologically by **Collapsing Focal Segmental Glomerulosclerosis (FSGS)** [1]. **Why Intravenous Drug Abusers (IVDAs) are the correct answer:** Epidemiological studies have consistently shown that HIVAN has a strong predilection for specific demographics. It is most common in **African Americans** (due to the APOL1 genetic risk variant) and **Intravenous Drug Abusers** [2]. The association with IVDAs is likely multifactorial, involving both the direct cytopathic effects of HIV on the glomerular epithelium and the potential synergistic renal damage caused by injected substances (like heroin, which independently causes "Heroin Nephropathy"). **Analysis of Incorrect Options:** * **A & B (Homosexuals and Heterosexuals):** While HIV is frequently transmitted via sexual routes, these subsets do not show a disproportionately higher incidence of HIVAN compared to the IVDA population, unless they also belong to the high-risk African American genotype. * **D (Congenital HIV):** While children with congenital HIV can develop renal disease, the classic "HIVAN" phenotype is significantly more prevalent in the adult IVDA population. **NEET-PG High-Yield Pearls:** * **Histology:** Collapsing FSGS is the hallmark (look for "wrinkling and collapse of the glomerular basement membrane") [1]. * **Clinical Presentation:** Rapidly progressive renal failure, heavy proteinuria (nephrotic range), and **normal-sized or enlarged kidneys** on ultrasound (unlike most chronic kidney diseases where kidneys shrink). * **Treatment:** Highly Active Antiretroviral Therapy (HAART) is the mainstay of treatment and can slow progression. * **Genetic Link:** Strongly associated with **APOL1 gene** polymorphisms on chromosome 22.

Q: Which acid-base disturbances are typically associated with sepsis?

Metabolic acidosis and respiratory alkalosis. In sepsis, the most characteristic acid-base disturbance is a **mixed disorder** consisting of **Metabolic Acidosis and Respiratory Alkalosis**. ### Why Option B is Correct: 1. **Metabolic Acidosis (High Anion Gap):** Sepsis leads to tissue hypoperfusion and cellular hypoxia. This forces cells into anaerobic metabolism, resulting in the overproduction of **lactic acid** (Lactic Acidosis). 2. **Respiratory Alkalosis:** This occurs early in sepsis due to a centrally mediated increase in respiratory drive. Endotoxins, fever, and the systemic inflammatory response syndrome (SIRS) stimulate the medullary respiratory center, leading to hyperventilation and a decrease in $PaCO_2$. ### Why Other Options are Incorrect: * **Option A:** Respiratory acidosis (high $PaCO_2$) only occurs in the terminal stages of sepsis if the patient develops respiratory muscle fatigue or ARDS; it is not the "typical" initial presentation. * **Options C & D:** Metabolic alkalosis is rare in sepsis unless there is significant concomitant vomiting or nasogastric suctioning. Sepsis is fundamentally a state of acid accumulation, not base excess. ### High-Yield Clinical Pearls for NEET-PG: * **Mixed Acid-Base Disorders:** When you see a low $HCO_3^-$ (metabolic acidosis) and a $PaCO_2$ lower than expected by Winters’ formula, suspect a primary respiratory alkalosis. * **Salicylate Poisoning:** This is the other classic condition that presents with the same mixed pattern (Metabolic Acidosis + Respiratory Alkalosis). * **Lactate:** Serum lactate levels are a key prognostic marker in the "Surviving Sepsis" guidelines; levels >2 mmol/L despite fluid resuscitation define septic shock.

Q: What is the most common inherited cause of renal disease?

Polycystic kidney disease. **Autosomal Dominant Polycystic Kidney Disease (ADPKD)** is the most common inherited cause of renal disease and the leading genetic cause of End-Stage Renal Disease (ESRD) worldwide [1]. It is characterized by the progressive development of numerous fluid-filled cysts in the renal parenchyma, leading to massive kidney enlargement and functional decline [1]. It is most commonly caused by mutations in the **PKD1** (Chromosome 16) or **PKD2** (Chromosome 4) genes [1]. **Analysis of Options:** * **Alport Syndrome:** This is an X-linked dominant (most common) or autosomal recessive disorder caused by mutations in Type IV collagen. While it is a significant cause of hereditary nephritis and deafness, its prevalence is much lower than ADPKD. * **Hypospadias:** This is a common congenital anatomical malformation of the male urethra, not an inherited "renal disease" or parenchymal pathology. * **Ureteropelvic Junction (UPJ) Obstruction:** This is the most common cause of *neonatal hydronephrosis*. While it can be congenital, it is typically a structural/obstructive anomaly rather than a primary inherited genetic renal disease. **High-Yield Clinical Pearls for NEET-PG:** * **Extra-renal manifestations of ADPKD:** Hepatic cysts (most common extra-renal site), Berry aneurysms (Circle of Willis), Mitral Valve Prolapse (MVP), and diverticulosis. * **Diagnosis:** Ultrasonography is the primary screening tool. * **Treatment:** Tolvaptan (Vasopressin V2 receptor antagonist) is used to slow the progression of cyst growth and renal decline. * **Inheritance:** ADPKD follows a "two-hit" hypothesis at the cellular level, though it is clinically inherited in an autosomal dominant pattern.

Q: Hypotension during dialysis is most commonly due to which of the following?

Excessive ultrafiltration. **Explanation:** **Intradialytic Hypotension (IDH)** is the most frequent complication encountered during hemodialysis, occurring in approximately 20–30% of sessions [1]. **1. Why Excessive Ultrafiltration is Correct:** The primary mechanism behind IDH is a **rapid decrease in plasma volume** caused by ultrafiltration (fluid removal) that exceeds the **plasma refilling rate** (the rate at which fluid moves from the interstitial space into the intravascular compartment) [1]. When the rate of fluid removal is too aggressive or the patient has gained excessive interdialytic weight, the compensatory mechanisms—such as peripheral vasoconstriction and increased cardiac output—fail to maintain blood pressure, leading to hypotension. **2. Analysis of Incorrect Options:** * **B. Antihypertensive medications:** While taking blood pressure medication shortly before dialysis can exacerbate hypotension, it is a modifiable risk factor rather than the *most common* primary cause. * **C. Underlying renal disease:** While the patient has renal failure (the reason for dialysis), the disease itself does not cause acute drops in BP during the procedure; rather, the process of fluid shifts does. * **D. Diabetes mellitus:** Diabetic patients are at a *higher risk* for IDH due to autonomic neuropathy (impaired vasoconstriction), but the inciting event remains the fluid removal process. **3. High-Yield Clinical Pearls for NEET-PG:** * **Definition:** IDH is typically defined as a decrease in systolic BP by **≥20 mmHg** or a decrease in mean arterial pressure by **10 mmHg** associated with clinical symptoms. * **Management:** Immediate management includes placing the patient in the **Trendelenburg position**, stopping ultrafiltration, and administering a **normal saline bolus**. * **Prevention:** Strategies include limiting interdialytic weight gain, extending dialysis time, or using "sodium modeling" and cool dialysate [1].

Question 1

Which investigation is most crucial for the diagnosis of idiopathic membranous glomerulopathy?

Accepted Answer

Antibody to PLA2R on podocytes

Answer

Kidney biopsy with immunofluorescent staining

Answer

C3, C4, and CH50 levels

Answer

c-ANCA titers

Question 2

At what serum potassium level does a sine wave pattern typically appear on an ECG?

Accepted Answer

> 8 mEq/dl

Answer

> 6 mEq/dl

Answer

> 7 mEq/dl

Answer

> 10 mEq/dl

Question 3

A 50-year-old diabetic patient presents with general malaise. On workup, his serum creatinine is 5.0 mg/dL and blood urea is 125 mg/dL. The urine MICRAL test is positive. Which of the following medications would be beneficial for this patient?

Accepted Answer

Diuretics

Answer

Cardio-selective beta-blocker

Answer

ACE inhibitor

Answer

Amiodarone

Question 4

HIV-induced nephropathy is more common in which of the following subsets of HIV patients?

Accepted Answer

Intravenous drug abusers

Answer

Homosexuals

Answer

Heterosexuals

Answer

Congenital HIV

Question 5

Which acid-base disturbances are typically associated with sepsis?

Accepted Answer

Metabolic acidosis and respiratory alkalosis

Answer

Metabolic acidosis and respiratory acidosis

Answer

Metabolic alkalosis and respiratory acidosis

Answer

Metabolic alkalosis and respiratory alkalosis

Question 6

What is the most common inherited cause of renal disease?

Accepted Answer

Polycystic kidney disease

Answer

Alport syndrome

Answer

Hypospadias

Answer

Ureteropelvic junction obstruction

Question 7

Hypotension during dialysis is most commonly due to which of the following?

Accepted Answer

Excessive ultrafiltration

Answer

Administration of antihypertensive medications

Answer

Underlying renal disease

Answer

Diabetes mellitus

Question 8

What is the most common neurological disorder seen in patients with chronic renal failure?

Accepted Answer

Polyneuropathy

Answer

Dementia

Answer

Restless leg syndrome

Answer

Encephalopathy

Question 9

Hemolytic Uremic Syndrome is characterized by which of the following?

Accepted Answer

Renal failure

Answer

Microangiopathic hemolytic anemia

Answer

Decreased LDH

Answer

Thrombocytopenia

Question 10

Which of the following conditions are associated with the presence of RBC casts?

Accepted Answer

Ankylosing Spondylitis

Answer

Diabetes Mellitus

Answer

Wegener's Granulomatosis

Answer

Systemic Lupus Erythematosus

Nephrology — MCQs

Nephrology — MCQs

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