Nephrology Practice Questions

Q: Which of the following causes hyperchloremic acidosis?

Ureterosigmoidostomy. ***Ureterosigmoidostomy*** - This procedure involves implanting ureters into the sigmoid colon, causing **urinary electrolytes** to be reabsorbed by the colon. - The colon reabsorbs **chloride** in exchange for **bicarbonate**, leading to **hyperchloremia** and **metabolic acidosis**. *Diarrhea leading to metabolic acidosis* - While diarrhea does cause **metabolic acidosis** due to bicarbonate loss, it is typically a **normochloremic** or anion-gap acidosis, not primarily hyperchloremic unless there are severe fluid losses or other complex factors. - The primary mechanism is loss of bicarbonate-rich fluid from the gastrointestinal tract, leading to a decrease in serum bicarbonate. *Ileoplasty not affecting acid-base status* - An **ileoplasty** (surgical reconstruction of the ileum) generally refers to procedures that do not inherently cause acid-base disturbances unless there are complications like obstruction or short bowel syndrome. - Unlike a ureterosigmoidostomy, the ileum is not typically used for urine draining in a way that leads to significant electrolyte exchange affecting systemic acid-base balance. *Vomiting causing metabolic alkalosis* - **Vomiting** leads to the loss of **gastric acid (HCl)**, which results in **hypochloremia** and metabolic alkalosis, not acidosis. - The loss of hydrogen ions and chloride from the stomach causes an increase in serum bicarbonate to maintain charge neutrality.

Q: Which inheritance pattern is associated with adult polycystic kidney disease?

Autosomal dominant. ***Autosomal dominant*** - Adult polycystic kidney disease (**APKD**) is primarily inherited in an **autosomal dominant** manner, meaning a single copy of the mutated gene can cause the disease [1]. - It is commonly associated with **bilateral renal cysts** and can lead to chronic kidney disease owing to the progressive nature of the cysts [1]. *X-linked dominant* - X-linked conditions predominantly affect **males**, and the characteristics of APKD do not align with X-linked inheritance patterns. - There are no known mechanisms or mutations related to APKD that operate through an **X-linked dominant** inheritance. *Autosomal recessive* - Autosomal recessive conditions require two copies of the mutated gene for expression, which is not the case in APKD. - This option is more characteristic of **infantile polycystic kidney disease**, which is rare and different from APKD. *X-linked recessive* - Similar to , X-linked recessive traits primarily affect **males**, which contradicts the established inheritance pattern of APKD. - The condition does not show linkage to **X chromosome** mutations, making this option incorrect.

Q: Positive urinary anion gap is found in which of the following conditions?

Renal tubular acidosis. ***Renal tubular acidosis*** - **Renal tubular acidosis (RTA)** results in impaired renal acid excretion, leading to a **positive urinary anion gap** [1]. - This occurs because the kidneys are unable to excrete sufficient amounts of **ammonium (NH4+)**, which is a primary urinary cation that balances excreted anions [1]. *Alcoholic ketoacidosis* - While alcoholic ketoacidosis causes a **high serum anion gap metabolic acidosis**, the urinary anion gap is typically **negative** due to increased excretion of ammonium to excrete excess acids. - The ketoacids (beta-hydroxybutyrate, acetoacetate) are the unmeasured anions contributing to the serum anion gap. *Diabetic ketoacidosis* - Similar to alcoholic ketoacidosis, **diabetic ketoacidosis (DKA)** presents with a high serum anion gap and a **negative urinary anion gap**. - The body compensates for the metabolic acidosis by increasing **ammonium excretion** in the urine. *Diarrhea* - Severe diarrhea causes **hyperchloremic metabolic acidosis** with a **normal serum anion gap** [1]. - The increased loss of bicarbonate in stool leads to renal compensation with increased acid excretion, resulting in a **negative urinary anion gap** as ammonium excretion rises.

Q: Uremic complications typically arise during which of the following phases of renal failure?

Maintenance. ***Maintenance*** - During the **maintenance phase**, renal function is severely impaired, leading to the accumulation of **uremic toxins** and metabolic waste products. - This prolonged period of reduced kidney function is when **uremic complications** such as pericarditis, encephalopathy, and coagulopathy typically manifest. *Initiation* - The **initiation phase** is characterized by the initial insult to the kidneys and the onset of reduced glomerular filtration, but significant uremic complications are usually not yet apparent. - It is a period of evolving injury, and the body's compensatory mechanisms may still be able to mitigate acute toxicity. *Diuretic Phase* - The **diuretic phase** is a period of gradual improvement from renal failure, where urine output increases, but the kidneys may still have impaired ability to concentrate urine or fully excrete waste. - While electrolyte imbalances can occur, severe uremic complications are less common as renal function starts to recover. *Recovery Phase* - In the **recovery phase**, renal function gradually normalizes, and the kidneys regain their ability to excrete waste products effectively. - Uremic complications would typically be resolving, not arising, during this phase as **renal repair** takes place.

Q: What is the most common cause of chronic renal failure?

Diabetes mellitus. ***Diabetes mellitus*** - **Diabetes mellitus** is the leading cause of **chronic renal failure (CRF)**, responsible for approximately 45-50% of all cases [2]. - Both type 1 and type 2 diabetes can lead to **diabetic nephropathy**, a progressive kidney disease that ultimately results in end-stage renal disease (ESRD) [1], [2]. *Glomerulonephritis (acute to chronic)* - While various forms of **glomerulonephritis** can cause chronic renal failure, they collectively account for a smaller percentage compared to diabetes. - The progression from acute to chronic glomerulonephritis is not as prevalent as diabetic nephropathy in the overall etiology of CRF. *Chronic pyelonephritis* - **Chronic pyelonephritis**, an infection-related kidney scarring, is a cause of CRF but is less common than diabetes and hypertension as primary drivers. - It often results from recurrent **urinary tract infections (UTIs)** and **vesicoureteral reflux**. *Hypertensive renal disease* - **Hypertension** is the second most common cause of CRF, often co-occurring with diabetes or contributing independently to renal damage [1], [2]. - Untreated or poorly controlled hypertension leads to **nephrosclerosis**, a hardening of the small arteries in the kidneys, impairing their function over time.

Q: Which of the following conditions is associated with hypokalemia and metabolic acidosis?

Diarrhea. ***Diarrhea*** - Profuse **diarrhea** leads to a significant loss of **bicarbonate** from the gastrointestinal (GI) tract, resulting in **metabolic acidosis**. - The loss of potassium-rich fluid from the GI tract also directly causes **hypokalemia** [1]. *Vomiting* - **Vomiting** leads to the loss of gastric acid (HCl), causing **metabolic alkalosis**, not acidosis [1]. - While it can cause **hypokalemia** due to renal compensation and direct loss, the acid-base disturbance is opposite to what is asked [1]. *Chronic kidney disease* - **Chronic kidney disease** often leads to impaired acid excretion, causing **metabolic acidosis**, but typically causes **hyperkalemia** due to reduced potassium excretion, especially in advanced stages [2]. - In earlier stages, potassium levels might be normal, but hypokalemia is not a characteristic feature. *Nasogastric suction* - **Nasogastric suction** removes gastric acid and fluids, similar to vomiting, leading to a loss of hydrogen ions and chloride. - This typically results in **metabolic alkalosis** and can cause **hypokalemia**, which is inconsistent with metabolic acidosis [1].

Q: Which of the following diseases is MOST likely to present with proteinuria?

Diabetic nephropathy. ***Glomerulonephritis*** [1], [2] - It is characterized by **inflammation of the glomeruli**, leading to significant **proteinuria** due to increased permeability [1]. - Commonly associated with **hematuria** and **edema**, which further supports its presence in renal pathology [1], [2]. *Polycystic kidney disease* - Mainly presents with **renal cysts** and may have **hematuria** but does not typically cause significant proteinuria early on. - Proteinuria can occur later due to renal insufficiency, but is not a hallmark feature of the disease. *Pyelonephritis* - This condition primarily causes **inflammatory changes** in the kidney due to infection, leading to **fever** and **flank pain**, rather than proteinuria. - While mild proteinuria may occur, it is usually characterized by **white blood cells** and bacteria in the urine rather than significant protein loss. *Ateriitis* - Typically refers to **inflammation of the arteries**, which does not involve kidney structures directly related to proteinuria [3]. - This condition is associated with other systemic symptoms but rarely presents with notable **urinary protein loss** [3].

Q: Which of the following is a cause of metabolic acidosis with a normal anion gap?

Renal tubular acidosis. ***Renal tubular acidosis*** - **Renal tubular acidosis (RTA)** is characterized by a defect in renal acid excretion or bicarbonate reabsorption, leading to **metabolic acidosis** with a **normal anion gap** [1]. - The deficiency in net acid excretion results in the retention of chloride ions to maintain electroneutrality, hence it's also known as **hyperchloremic metabolic acidosis** [1]. *Diabetic ketoacidosis* - **Diabetic ketoacidosis (DKA)** is a high anion gap metabolic acidosis caused by the accumulation of **ketoacids** (beta-hydroxybutyrate, acetoacetate). - These unmeasured anions increase the anion gap, distinguishing it from normal anion gap acidosis. *Aspirin poisoning* - **Aspirin (salicylate) poisoning** typically causes a **mixed acid-base disorder** with both metabolic acidosis and respiratory alkalosis [1]. - The metabolic acidosis component is a **high anion gap acidosis** due to the accumulation of salicylates and their metabolites. *Lactic acidosis* - **Lactic acidosis** is a common cause of **high anion gap metabolic acidosis**, resulting from the overproduction or decreased clearance of **lactate** [1]. - The increased concentration of lactate, an unmeasured anion, leads to the widening of the anion gap.

Q: Which of the following is an early symptom of hypermagnesemia?

Loss of deep tendon reflexes (DTR). Loss of deep tendon reflexes (DTR) - Loss of deep tendon reflexes (DTRs) is one of the earliest and most reliable signs of increasing magnesium toxicity, often occurring when serum magnesium levels are between 4-6 mEq/L. - This symptom reflects the neuromuscular blocking effects of magnesium, which reduces acetylcholine release at the neuromuscular junction [1]. *Hypotension* - Hypotension is a later and more severe symptom of hypermagnesemia, typically occurring at higher magnesium levels (e.g., above 6 mEq/L). - It results from the vasodilating effects of magnesium on smooth muscle, leading to decreased peripheral vascular resistance. *Diarrhea* - Diarrhea is actually a common side effect of oral magnesium supplementation, as magnesium acts as an osmotic laxative. - It is generally *not* an early symptom of systemic hypermagnesemia resulting from impaired excretion or excessive parenteral administration. *Arrhythmias* - Arrhythmias, particularly bradycardia and heart block, are significant and *late-stage* cardiac complications of severe hypermagnesemia (often above 8-10 mEq/L). - These are caused by magnesium's interference with myocardial conduction and are more dangerous than early DTR changes.

Question 1

Which of the following causes hyperchloremic acidosis?

Accepted Answer

Ureterosigmoidostomy

Answer

Diarrhea leading to metabolic acidosis

Answer

Ileoplasty not affecting acid-base status

Answer

Vomiting causing metabolic alkalosis

Question 2

A 63-year-old man is in stable condition after an acute myocardial infarction when he becomes hypotensive for 3 hours before paramedical personnel arrive. Over the next week, the serum urea nitrogen level increases to 48 mg/dL, the serum creatinine level increases to 5 mg/dL, and the urine output decreases. He undergoes hemodialysis for the next 2 weeks and then develops marked polyuria, with a urine output of 2 to 3 L/day. His renal function gradually returns to normal. Which of the following substances is most likely released and participated in the elevation of BUN, creatinine, and reduced urinary output?

Accepted Answer

Endothelin (vasoconstrictor released in response to ischemia)

Answer

Aldosterone (involved in fluid retention)

Answer

Natriuretic peptide (responds to heart failure)

Answer

Erythropoietin (stimulates red blood cell production)

Question 3

Which inheritance pattern is associated with adult polycystic kidney disease?

Accepted Answer

Autosomal dominant

Answer

Autosomal recessive

Answer

X-linked recessive

Answer

X-linked dominant

Question 4

Positive urinary anion gap is found in which of the following conditions?

Accepted Answer

Renal tubular acidosis

Answer

Diabetic ketoacidosis

Answer

Diarrhea

Answer

Alcoholic ketoacidosis

Question 5

Uremic complications typically arise during which of the following phases of renal failure?

Accepted Answer

Maintenance

Answer

Initiation

Answer

Diuretic Phase

Answer

Recovery Phase

Question 6

What is the most common cause of chronic renal failure?

Accepted Answer

Diabetes mellitus

Answer

Glomerulonephritis (acute to chronic)

Answer

Chronic pyelonephritis

Answer

Hypertensive renal disease

Question 7

Which of the following conditions is associated with hypokalemia and metabolic acidosis?

Accepted Answer

Diarrhea

Answer

Vomiting

Answer

Chronic kidney disease

Answer

Nasogastric suction

Question 8

Which of the following diseases is MOST likely to present with proteinuria?

Accepted Answer

Diabetic nephropathy

Answer

Aneurysms

Answer

Polycystic kidney disease

Answer

Glomerulonephritis

Question 9

Which of the following is a cause of metabolic acidosis with a normal anion gap?

Accepted Answer

Renal tubular acidosis

Answer

Diabetic ketoacidosis

Answer

Aspirin poisoning

Answer

Lactic acidosis

Question 10

Which of the following is an early symptom of hypermagnesemia?

Accepted Answer

Loss of deep tendon reflexes (DTR)

Answer

Arrhythmias

Answer

Diarrhea

Answer

Hypotension

Nephrology — MCQs

Nephrology — MCQs

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