Nephrology Practice Questions

Q: Fluid containing which of the following substances is used in peritoneal dialysis?

Dextrose. **Explanation:** The primary goal of peritoneal dialysis (PD) is to remove excess water and metabolic waste products from the blood. This is achieved through the processes of **osmosis** and **diffusion** across the peritoneal membrane [1]. **Why Dextrose is the Correct Answer:** Dextrose (glucose) serves as the **osmotic agent** in the PD fluid [1]. By creating a high osmotic pressure in the peritoneal cavity relative to the blood, it draws excess water out of the intravascular space and into the dialysate (ultrafiltration) [2]. Standard PD fluids contain dextrose in varying concentrations (e.g., 1.5%, 2.5%, or 4.25%) to tailor the amount of fluid removal required. **Analysis of Incorrect Options:** * **A. NaCl:** While PD fluid contains sodium chloride to maintain electrolyte balance and isotonicity, it is not the active substance used to drive the dialysis process or fluid removal. * **B. Urea:** Urea is a metabolic waste product that PD aims to *remove* from the body. Including it in the dialysate would prevent the concentration gradient necessary for its diffusion out of the blood. * **C. Heparin:** Heparin is sometimes added to PD bags to prevent fibrin clots from plugging the catheter (especially during peritonitis), but it is a pharmacological additive, not a constituent of the standard dialysis process itself. **Clinical Pearls for NEET-PG:** * **Icodextrin:** A glucose polymer used as an alternative osmotic agent for long dwells (e.g., overnight) in patients with high transport characteristics or diabetes. * **Peritonitis:** The most common complication of PD; the most frequent causative organism is *Staphylococcus epidermidis*. * **Contraindication:** PD is generally avoided in patients with recent abdominal surgery or extensive intra-abdominal adhesions.

Q: A 14-year-old boy was brought in a collapsed state with a history of 2 episodes of vomiting and presented with a feeble pulse and cold, clammy limbs. ECG is provided. What is the diagnosis?

Hyperkalemia. ***Hyperkalemia*** - ECG findings of **peaked T-waves**, **widened QRS complexes**, and **absent P-waves** are pathognomonic for severe hyperkalemia. - The clinical presentation of **cardiovascular collapse** with feeble pulse and cold, clammy limbs indicates life-threatening hyperkalemia causing cardiac conduction abnormalities. *Hypokalemia* - ECG would show **U-waves**, **flat or inverted T-waves**, and **prolonged QT interval**, not peaked T-waves. - Clinical presentation would include **muscle weakness** and **cramping**, not the acute cardiovascular collapse seen here. *Hypocalcemia* - ECG characteristic is **prolonged QT interval** due to delayed ventricular repolarization, not peaked T-waves. - Clinical features include **tetany**, **Chvostek's sign**, and **Trousseau's sign**, not cardiovascular collapse. *Hypomagnesemia* - ECG shows **torsades de pointes** and **prolonged QT interval**, similar to hypocalcemia findings. - Often associated with **concurrent hypokalemia** and **hypocalcemia**, presenting with neuromuscular irritability rather than cardiac collapse.

Q: A normal anion gap metabolic acidosis occurs in patients with which of the following conditions?

Diarrhea. **Explanation:** Metabolic acidosis is categorized based on the **Anion Gap (AG)**, calculated as $[Na^+] - ([Cl^-] + [HCO_3^-])$. A **Normal Anion Gap Metabolic Acidosis (NAGMA)**, also known as hyperchloremic acidosis, occurs when the loss of bicarbonate ($HCO_3^-$) is compensated by a proportional increase in chloride ($Cl^-$) to maintain electroneutrality. **Why Diarrhea is Correct:** Gastrointestinal secretions below the stomach (pancreatic, biliary, and intestinal fluids) are rich in bicarbonate. In **diarrhea**, there is a direct loss of $HCO_3^-$ from the body. To balance the loss of these negative ions, the kidneys retain chloride, leading to a hyperchloremic NAGMA. **Analysis of Incorrect Options:** * **Renal Failure:** In advanced chronic kidney disease, the kidneys fail to excrete fixed organic acids (phosphates, sulfates). these unmeasured anions accumulate, causing a **High Anion Gap Metabolic Acidosis (HAGMA)**. * **Salicylate Poisoning:** Salicylates are exogenous acids. Their accumulation increases unmeasured anions, leading to **HAGMA** (often co-existing with respiratory alkalosis). * **Methanol Poisoning:** Methanol is metabolized into formic acid. The accumulation of formate ions results in **HAGMA**. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for NAGMA (USED CARP):** **U**reterosigmoidostomy, **S**aline infusion, **E**ndocrine (Addison’s), **D**iarrhea, **C**arbonic anhydrase inhibitors (Acetazolamide), **A**mmonium chloride, **R**enal tubular acidosis (RTA), **P**ancreatic fistula. * **Mnemonic for HAGMA (MUDPILES):** **M**ethanol, **U**remia, **D**KA, **P**araldehyde, **I**soniazid/Iron, **L**actic acidosis, **E**thylene glycol, **S**alicylates. * **Key Distinction:** If the question mentions "Renal Tubular Acidosis" (RTA), it is always NAGMA; if it mentions "Renal Failure/Uremia," it is HAGMA.

Q: Which of the following is a true complication of hemodialysis?

Cardiovascular complications. **Explanation:** **Cardiovascular complications (Option B)** are the leading cause of morbidity and mortality in patients undergoing long-term hemodialysis (HD), accounting for nearly 50% of deaths. The underlying pathophysiology involves a combination of traditional risk factors (hypertension, diabetes) and uremia-specific factors (chronic fluid overload, electrolyte imbalances, and systemic inflammation). These lead to accelerated atherosclerosis, left ventricular hypertrophy (LVH), and arrhythmias. **Analysis of Incorrect Options:** * **Beta-amyloid deposition (Option A):** This is incorrect because the amyloidosis associated with long-term dialysis is specifically due to **Beta-2 Microglobulin ($\beta_2$M)** deposition, not Beta-amyloid (which is associated with Alzheimer’s disease). $eta_2$M is poorly cleared by standard dialysis membranes, leading to carpal tunnel syndrome and bone cysts. * **Renal rickets (Option C):** This is a manifestation of Chronic Kidney Disease (CKD) itself (part of CKD-Mineral Bone Disorder) due to Vitamin D deficiency and secondary hyperparathyroidism, rather than a complication *caused* by the dialysis procedure [1]. * **Metabolic acidosis (Option D):** Hemodialysis is a **treatment** for metabolic acidosis, not a complication [2]. Dialysate contains bicarbonate or acetate to buffer the acid load in uremic patients. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause of death in HD:** Cardiovascular disease (specifically sudden cardiac death). * **Dialysis Equilibrium Syndrome:** A serious neurological complication caused by the rapid removal of urea, leading to cerebral edema. * **First-use syndrome:** An anaphylactoid reaction (Type 1 hypersensitivity) often seen with ethylene oxide-sterilized membranes. * **Infection:** The second most common cause of death; Staphylococcus aureus is the most common pathogen related to vascular access [2].

Q: A patient presents with hyperkalemia and no ECG changes. Which of the following is used for treatment, EXCEPT?

Calcium gluconate. In the management of hyperkalemia, treatment is categorized into three goals: membrane stabilization, shifting potassium into cells, and removing potassium from the body [1]. **Why Calcium Gluconate is the correct answer:** Calcium gluconate (or calcium chloride) is used specifically for **membrane stabilization**. It antagonizes the cardiotoxic effects of high potassium by stabilizing the resting membrane potential of cardiomyocytes [1]. However, it does **not** lower serum potassium levels. It is strictly indicated only when there are **ECG changes** (e.g., peaked T-waves, PR prolongation, widened QRS) or severe hyperkalemia (>6.5 mEq/L) [1]. Since this patient has **no ECG changes**, calcium gluconate is not indicated [1]. **Explanation of other options (Incorrect because they DO treat hyperkalemia):** * **A. Glucose + Insulin:** Insulin promotes the shift of potassium from the extracellular to the intracellular fluid by stimulating the Na+/K+-ATPase pump. Glucose is co-administered to prevent hypoglycemia. * **B. Sodium Bicarbonate:** This induces alkalosis, which causes a hydrogen-potassium exchange, shifting potassium into the cells. It is particularly useful if the patient has underlying metabolic acidosis. * **C. Resins (e.g., Polystyrene sulfonate):** These are cation-exchange resins that bind potassium in the GI tract in exchange for sodium or calcium, facilitating the actual removal of potassium from the body. **NEET-PG High-Yield Pearls:** * **Earliest ECG change:** Tall, tented/peaked T-waves. * **Most definitive treatment:** Hemodialysis. * **Salbutamol (Nebulized):** Another "shifter" that can be used to lower serum potassium. * **Calcium Gluconate vs. Chloride:** Calcium gluconate is preferred for peripheral lines as it is less caustic than calcium chloride.

Q: A 25-year-old man presents with a kidney stone. He is married to his first cousin, and six months earlier, his 8-year-old son also had a kidney stone. What is the most likely diagnosis?

Cystinuria. The clinical presentation points toward **Cystinuria**, an autosomal recessive disorder characterized by a defect in the proximal renal tubular amino acid transporter for **COLA** (Cystine, Ornithine, Lysine, and Arginine). **Why Cystinuria is correct:** 1. **Inheritance Pattern:** The mention of a "first-cousin marriage" (consanguinity) strongly suggests an **autosomal recessive** inheritance. 2. **Early Onset:** Kidney stones in an 8-year-old child are highly suggestive of metabolic or genetic defects rather than lifestyle-related urolithiasis [1]. 3. **Pathophysiology:** In cystinuria, the failure to reabsorb cystine leads to high urinary concentrations. Because cystine is poorly soluble in acidic urine, it precipitates to form **hexagonal crystals** and radiolucent (or faintly radiopaque) stones. **Why other options are incorrect:** * **ADPKD:** Follows an autosomal dominant pattern (usually presents in the 3rd–4th decade) and is characterized by bilateral large cystic kidneys and hypertension, not isolated stones in childhood [2]. * **Medullary Cystic Kidney Disease:** Now known as ADTKD, it is autosomal dominant and typically presents with polyuria, salt wasting, and progression to ESRD, rather than recurrent nephrolithiasis [3]. * **Fanconi Syndrome:** Involves a generalized proximal tubule defect (loss of glucose, amino acids, phosphate, etc.). While it causes phosphaturia, it is not a classic cause of recurrent childhood stones. **High-Yield Clinical Pearls for NEET-PG:** * **Diagnosis:** The **Sodium Nitroprusside test** (Cyanide-nitroprusside test) turns urine purple/red in the presence of cystine. * **Microscopy:** Pathognomonic **hexagonal (benzene ring)** crystals. * **Management:** High fluid intake, **urinary alkalinization** (pH > 7.5), and chelating agents like **Penicillamine** or Tiopronin for refractory cases.

Q: What is the cornerstone of therapy for chronic hyponatremia?

Water deprivation. The cornerstone of therapy for chronic hyponatremia is **Water Deprivation (Fluid Restriction)** [1]. In chronic cases, the body has had time to adapt to lower osmolarity by shedding intracellular organic osmolytes. Rapid correction can lead to Osmotic Demyelination Syndrome (ODS) [1]. Fluid restriction (typically <800–1000 mL/day) is the safest and most effective first-line strategy, particularly in SIADH, as it forces the body to utilize and excrete existing free water, gradually raising serum sodium levels [1]. **Analysis of Options:** * **Hypertonic 3% Saline:** This is the treatment of choice for **acute symptomatic** hyponatremia or emergencies (seizures, coma). In chronic cases, it is avoided unless the patient is severely symptomatic due to the high risk of ODS. * **Vasopressin Antagonists (Vaptans):** While effective for euvolemic and hypervolemic hyponatremia, they are considered second-line therapy due to cost, potential hepatotoxicity (Tolvaptan), and the risk of over-correction. * **Demeclocycline:** This antibiotic induces a form of nephrogenic diabetes insipidus. It is used only in chronic SIADH when fluid restriction fails, but it is rarely a first-line choice due to nephrotoxicity [1]. **NEET-PG High-Yield Pearls:** * **Rate of Correction:** In chronic hyponatremia, do not exceed a correction rate of **8–10 mEq/L in 24 hours** (or <18 mEq/L in 48 hours) [1]. * **ODS Risk:** The pons is most susceptible (Central Pontine Myelinolysis). Clinical features include "locked-in syndrome," dysarthria, and dysphagia, appearing days after rapid correction [1]. * **Formula:** Use the Adrogue-Madias formula to calculate the change in serum sodium per liter of infusate.

Q: Which of the following is the LEAST likely to be associated with gross hematuria?

Acute glomerulonephritis. The key to answering this question lies in distinguishing between **glomerular** and **extra-glomerular (urological)** causes of hematuria. **Why Option A is correct:** In **Acute Glomerulonephritis (AGN)**, red blood cells leak through the damaged glomerular basement membrane [1]. This process is typically slow and associated with significant transit time through the nephron, leading to **microscopic hematuria**. When the hematuria is visible, it classically presents as "cola-colored" or "smoky" urine due to the formation of acid hematin. While visible, it is rarely "gross" or bright red with clots, making it the least likely cause of frank, gross hematuria among the choices provided. **Why the other options are incorrect:** * **Renal Trauma (B):** Direct injury to the renal parenchyma or vasculature often leads to significant, bright red bleeding into the collecting system, frequently resulting in gross hematuria. * **Ureteral Calculi (C):** Stones cause mechanical trauma and mucosal erosion as they pass through the ureter. This is a classic cause of sudden-onset gross hematuria, often accompanied by renal colic. * **Acute Cystitis (D):** Severe inflammation of the bladder mucosa (especially in hemorrhagic cystitis) commonly leads to terminal or total gross hematuria [1]. **NEET-PG High-Yield Pearls:** 1. **Glomerular vs. Non-Glomerular:** Glomerular bleeding [1] is characterized by **dysmorphic RBCs** (acanthocytes) and **RBC casts**. Non-glomerular bleeding (trauma, stones, malignancy) features **monomorphic RBCs** and often includes **blood clots**. 2. **Clots:** The presence of blood clots *always* indicates a non-glomerular (urological) source, as urinary urokinase in the tubules inhibits clot formation in glomerular diseases. 3. **Initial vs. Terminal Hematuria:** Initial hematuria suggests a urethral source; terminal hematuria suggests the bladder neck or prostatic urethra.

Question 1

Fluid containing which of the following substances is used in peritoneal dialysis?

Accepted Answer

Dextrose

Answer

NaCl

Answer

Urea

Answer

Heparin

Question 2

Calciphylaxis is more commonly seen in which of the following conditions?

Accepted Answer

Secondary hyperparathyroidism

Answer

Primary hyperparathyroidism

Answer

Tertiary hyperparathyroidism

Answer

Pseudohyperparathyroidism

Question 3

A 14-year-old boy was brought in a collapsed state with a history of 2 episodes of vomiting and presented with a feeble pulse and cold, clammy limbs. ECG is provided. What is the diagnosis?

Accepted Answer

Hyperkalemia

Answer

Hypokalemia

Answer

Hypocalcemia

Answer

Hypomagnesemia

Question 4

A normal anion gap metabolic acidosis occurs in patients with which of the following conditions?

Accepted Answer

Diarrhea

Answer

Renal failure

Answer

Salicylate poisoning

Answer

Methanol poisoning

Question 5

Which of the following is a true complication of hemodialysis?

Accepted Answer

Cardiovascular complications

Answer

Beta-amyloid deposition

Answer

Renal rickets

Answer

Metabolic acidosis

Question 6

A patient presents with hyperkalemia and no ECG changes. Which of the following is used for treatment, EXCEPT?

Accepted Answer

Calcium gluconate

Answer

Glucose + Insulin

Answer

Sodium bicarbonate

Answer

Resins

Question 7

A 58-year-old man with cirrhosis complains of worsening fatigue and confusion over the past 5 days. He also reports a declining urinary output over the past 48 hours. On examination, he is gaunt and jaundiced. He has tense ascites and a liver span of 7 cm in the midclavicular line. Lab results reveal a WBC 4600/mm3, Hb 9.4 g/dL, and PCB 29%. BUN of 34 mg/dL and a creatinine of 3.1 mg/dL. A urinary Na <10 mEq/L. What is the most appropriate treatment for his elevated BUN and creatinine?

Accepted Answer

Liver transplantation

Answer

Large volume paracentesis

Answer

Hemodialysis

Answer

Mesocaval shunt

Question 8

A 25-year-old man presents with a kidney stone. He is married to his first cousin, and six months earlier, his 8-year-old son also had a kidney stone. What is the most likely diagnosis?

Accepted Answer

Cystinuria

Answer

Autosomal dominant polycystic kidney disease (ADPKD)

Answer

Medullary cystic kidney disease

Answer

Fanconi syndrome

Question 9

What is the cornerstone of therapy for chronic hyponatremia?

Accepted Answer

Water deprivation

Answer

Vasopressin antagonists

Answer

Hypertonic 3% saline

Answer

Demeclocycline

Question 10

Which of the following is the LEAST likely to be associated with gross hematuria?

Accepted Answer

Acute glomerulonephritis

Answer

Renal trauma

Answer

Ureteral calculi

Answer

Acute cystitis

Nephrology — MCQs

Nephrology — MCQs

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