Nephrology Practice Questions

Q: A diabetic patient presents with hyperkalemia and urinary pH < 5.5. What is the MOST likely underlying cause?

Type IV RTA. ***Type IV RTA*** - Patients with **diabetes mellitus** frequently develop **hyporeninemic hypoaldosteronism**, leading to Type IV RTA [1]. - This condition is characterized by **hyperkalemia** and **acidosis** with a paradoxically low urinary pH (typically < 5.5). *Uremia* - **Uremia** can cause hyperkalemia and acidosis, but it is a broader term for severe kidney failure and not the most specific underlying cause for the given urinary findings. - While patients with uremia can have aciduria, the combination of **diabetic hyperkalemia** and acid urine points more directly to a specific tubular defect. *Primary hyperaldosteronism* - **Primary hyperaldosteronism** is characterized by **hypertension**, **hypokalemia**, and metabolic alkalosis, which is the opposite of the patient's presentation [1]. - This condition involves excessive aldosterone production, leading to increased potassium excretion [1]. *Type I Renal tubular acidosis* - **Type I RTA** (distal RTA) is characterized by the inability to acidify urine, resulting in a **urinary pH > 5.5** despite systemic acidosis [1]. - While it can cause hypokalemia (due to increased distal K+ secretion) and acidosis, the elevated urinary pH is a key differentiating factor from this patient's presentation [1].

Q: Interstitial nephritis is common with

Nonsteroidal anti-inflammatory drugs (NSAIDs). ***Nonsteroidal anti-inflammatory drugs (NSAIDs)*** - **NSAIDs** are a known cause of **acute interstitial nephritis** (AIN), an inflammatory condition affecting the tubules and interstitium of the kidney [1]. - This adverse reaction often manifests as **fever**, **rash**, **eosinophilia**, and **acute kidney injury**, typically 7-10 days after drug exposure. *Black water fever* - **Blackwater fever** is a severe complication of **malaria**, characterized by massive hemolysis leading to **hemoglobinuria**, which darkens the urine. - It primarily causes **acute kidney injury** through **acute tubular necrosis** due to hemoglobin precipitation in the renal tubules, not interstitial nephritis. *Rhabdomyolysis* - **Rhabdomyolysis** involves the breakdown of muscle tissue, releasing myoglobin into the bloodstream, which is toxic to the kidneys. [1] - This condition leads to **acute kidney injury** predominantly through **acute tubular necrosis** due to myoglobin casts obstructing tubules and direct toxicity, not interstitial inflammation. *Tumor lysis syndrome* - **Tumor lysis syndrome** occurs when large numbers of cancer cells are rapidly destroyed, releasing intracellular contents like potassium, phosphate, and nucleic acids. - The high concentration of **uric acid** and **phosphate** in the renal tubules leads to crystal formation, causing **acute kidney injury** primarily through **acute uric acid nephropathy** and **phosphate nephropathy**, rather than interstitial nephritis [1].

Q: Which of the following is not an absolute indication for hemodialysis?

GI bleeding. ***GI bleeding*** - While patients on dialysis may experience gastrointestinal bleeding, it is not a direct indication for initiating or continuing **hemodialysis**. - **GI bleeding** in end-stage renal disease (ESRD) patients can be due to various causes and requires specific management of the bleeding itself, not necessarily an alteration in dialysis prescription. *Convulsions* - **Convulsions** in patients with renal failure, especially due to uremia, are a severe manifestation of **uremic encephalopathy**. - This is an absolute indication for **hemodialysis** as it rapidly removes uremic toxins causing central nervous system dysfunction. *Pericarditis* - **Uremic pericarditis**, characterized by inflammation of the pericardium due to accumulation of uremic toxins, is a serious complication of renal failure. - It is an absolute indication for **hemodialysis** to prevent further cardiac complications like cardiac tamponade. *Hyperkalemia of 6.5 mEq/L* - Severe **hyperkalemia** (typically > 6.0-6.5 mEq/L) is a life-threatening electrolyte imbalance that can cause cardiac arrhythmias. - **Hemodialysis** is highly effective in rapidly removing potassium from the body and is an absolute indication, especially if unresponsive to other medical therapies.

Q: Which of the following is a characteristic finding in distal RTA?

Hypercalciuria. ***Hypercalciuria*** - **Hypercalciuria** is a characteristic finding in distal RTA (Type 1), leading to increased calcium in the urine. - This occurs due to reduced **distal tubular reabsorption of calcium** and increased bone resorption from chronic acidosis. *Urine pH 5.5** [1]. - A urine pH < 5.5 would suggest a normal kidney response to systemic acidosis, ruling out distal RTA. *Hypokalemia* - While hypokalemia can occur in distal RTA, it is not always present and is not the most definitive characteristic finding. - **Hypokalemia** is more characteristic of Type 1 RTA due to increased potassium excretion in an attempt to excrete H+ ions. *Nephrolithiasis* - **Nephrolithiasis** (kidney stones) is a common complication of distal RTA due to hypercalciuria and alkaline urine [2]. - However, hypercalciuria is the *reason* for the increased risk of nephrolithiasis, making it a more fundamental characteristic finding.

Q: Which of the following is a sign of Bartter's syndrome?

Low potassium levels. ***Low potassium levels*** * Bartter's syndrome is characterized by **renal salt wasting** and subsequent volume depletion, which activates the **renin-angiotensin-aldosterone system** [1]. * This leads to increased aldosterone levels, causing increased potassium secretion in the collecting ducts, resulting in **hypokalemia** [2]. *High potassium levels* * **Hyperkalemia** is not a feature of Bartter's syndrome; instead, it is marked by persistent potassium loss [1]. * Conditions causing hyperkalemia typically involve impaired renal potassium excretion or increased potassium release from cells. *Acidic blood* * Bartter's syndrome usually presents with **metabolic alkalosis** due to hydrogen ion loss in the urine, not acidic blood [2]. * Acidic blood (**acidemia**) would imply a state of respiratory or metabolic acidosis. *High sodium levels* * Bartter's syndrome primarily involves **renal salt wasting**, leading to **normal or low sodium levels** rather than high sodium levels. * High sodium levels (**hypernatremia**) are usually due to inadequate water intake or excessive water loss.

Q: What is the expected Transtubular Potassium Gradient (TTKG) in a patient with hypokalemia due to extrarenal losses?

< 3-4. ***< 3-4*** - A **Transtubular Potassium Gradient (TTKG)** of less than 3-4 indicates appropriate renal potassium conservation in response to hypokalemia. - This suggests that the hypokalemia is likely due to **extrarenal losses**, such as gastrointestinal losses (diarrhea, vomiting) or inadequate dietary intake, as the kidneys are working to retain potassium. *3-4* - A TTKG value in this range is typically considered indeterminate but could still point towards appropriate renal conservation if other clinical signs of extrarenal losses are present. - However, it does not as strongly confirm appropriate renal conservation as a value clearly below 3. *> 4-5* - A TTKG greater than 4-5 suggests **inappropriate renal potassium excretion** for a patient with hypokalemia. - This would indicate that the kidneys are complicit in the potassium loss, pointing towards renal causes of hypokalemia, such as **mineralocorticoid excess** or **diuretic use**. *> 5-6* - A TTKG greater than 5-6 strongly indicates significant **renal potassium wasting**. - This would be seen in conditions where the kidneys are actively secreting potassium despite hypokalemia, thereby contributing to the low potassium levels rather than conserving it.

Q: ECG image showing U wave. Patient is on furosemide and beta blocker. What is the most likely diagnosis?

Hypokalemia. ***Hypokalemia*** - The presence of **U waves** on an ECG is a classic sign of **hypokalemia**, often seen when serum potassium levels drop below 3.0 mEq/L. - The patient is taking **furosemide**, a loop diuretic, which commonly causes potassium loss and thus **hypokalemia**. *Hypocalcemia* - Hypocalcemia typically manifests on an ECG as a **prolonged QT interval**, not prominent U waves. - While furosemide can affect calcium, it usually leads to **hypercalcemia** due to volume contraction, not hypocalcemia. *Hyperkalemia* - Hyperkalemia is characterized by **tall, peaked T waves**, a **prolonged PR interval**, and a **widened QRS complex** on an ECG. U waves are absent. - Furosemide *causes* potassium excretion, making hyperkalemia an unlikely finding in this context. *Hypercalcemia* - Hypercalcemia typically causes a **shortened QT interval** on an ECG. U waves are not a feature. - While furosemide may sometimes lead to slight increases in calcium, it is not associated with U waves.

Q: What is the recommended rate of correction for sodium deficit in patients with chronic hyponatremia?

0.5 mmol/hour. ***0.5 mmol/hour*** [1] - This rate of correction is recommended to avoid **osmotic demyelination syndrome (ODS)**, also known as central pontine myelinolysis [1]. - The aim is to correct the sodium deficit gradually, with a maximum increase not exceeding **8-10 mmol/L in any 24-hour period** [1]. *1 mmol/hour* - This rate is generally considered too rapid for chronic hyponatremia and increases the risk of **osmotic demyelination syndrome**. - While acceptable in some acute severe cases, it is typically avoided in chronic settings where the brain has adapted to lower osmolality. *1.5 mmol/hour* - This rate would lead to an even faster correction of sodium, significantly elevating the risk of **osmotic demyelination syndrome**. - It would result in a correction of 36 mmol/L over 24 hours, far exceeding the recommended daily limit of 8-10 mmol/L. *2.0 mmol/hour* - Such a rapid correction rate is highly dangerous and almost guarantees the development of **osmotic demyelination syndrome**. - This aggressive correction would lead to severe brain injury due to rapid osmotic shifts.

Q: Which of the following statements about HIV associated nephropathy (HIVAN) is incorrect?

HIVAN is associated with shrunken kidneys.. ***Shrunken kidneys*** - In HIV-associated nephropathy, kidneys typically appear **enlarged** due to hyperplasia of podocytes and other glomerular changes. - **Shrunken kidneys** are not a characteristic feature, making this statement incorrect. *Develops when CD4<200* - HIV-associated nephropathy often arises when CD4 counts drop **below 200 cells/mm³**, indicating severe immunosuppression. - This is a common threshold for the occurrence of opportunistic infections and kidney issues in HIV patients. *15% cases show mesengial proliferation* - **Mesangial proliferation** can occur in about **15% to 30%** of cases of HIV-associated nephropathy, which aligns with the typical histological findings. - Incorrect assumptions might stem from misunderstanding the varying morphologies associated with HIV nephropathy. *Proteinuria* - **Proteinuria** is a common clinical feature of HIV-associated nephropathy, with the condition often presenting with significant protein loss in the urine. - The nephropathy especially results in **nephrotic syndrome**, characterized by high levels of proteinuria.

Q: Which of the following is not a typical feature of haemolytic uremic syndrome?

Splenomegaly. ***Neuro psychiatric disturbances*** - Neuropsychiatric disturbances are not a direct feature of hemolytic uremic syndrome (HUS), which primarily affects renal and hematological systems. - HUS is characterized by a triad of **hemolytic anemia**, **thrombocytopenia**, and **acute renal failure**, without specific neuropsychiatric manifestations [2]. *Anaemia* - **Hemolytic anemia** is a key feature of HUS due to red blood cell destruction [1], [2]. - Patients often exhibit signs of **fatigue and pallor**, distinguishing it from other renal syndromes [3]. *Renal microthrombi* - HUS is characterized by the formation of **microthrombi in renal vasculature**, leading to acute kidney injury [1]. - The presence of these microthrombi is fundamental to the pathology of HUS [1]. *Hyperkalemia* - Renal failure in HUS can lead to **hyperkalemia** due to decreased potassium excretion. - It is a common complication associated with the acute renal failure seen in HUS.

Question 1

A diabetic patient presents with hyperkalemia and urinary pH < 5.5. What is the MOST likely underlying cause?

Accepted Answer

Type IV RTA

Answer

Uremia

Answer

Primary hyperaldosteronism

Answer

Type I Renal tubular acidosis

Question 2

Interstitial nephritis is common with

Accepted Answer

Nonsteroidal anti-inflammatory drugs (NSAIDs)

Answer

Black water fever

Answer

Rhabdomyolysis

Answer

Tumor lysis syndrome

Question 3

Which of the following is not an absolute indication for hemodialysis?

Accepted Answer

GI bleeding

Answer

Convulsions

Answer

Pericarditis

Answer

Hyperkalemia of 6.5 mEq/L

Question 4

Which of the following is a characteristic finding in distal RTA?

Accepted Answer

Hypercalciuria

Answer

Urine pH < 5.5

Answer

Hypokalemia

Answer

Nephrolithiasis

Question 5

Which of the following is a sign of Bartter's syndrome?

Accepted Answer

Low potassium levels

Answer

High potassium levels

Answer

Acidic blood

Answer

High sodium levels

Question 6

What is the expected Transtubular Potassium Gradient (TTKG) in a patient with hypokalemia due to extrarenal losses?

Accepted Answer

< 3-4

Answer

3-4

Answer

> 4-5

Answer

> 5-6

Question 7

ECG image showing U wave. Patient is on furosemide and beta blocker. What is the most likely diagnosis?

Accepted Answer

Hypokalemia

Answer

Hypocalcemia

Answer

Hyperkalemia

Answer

Hypercalcemia

Question 8

What is the recommended rate of correction for sodium deficit in patients with chronic hyponatremia?

Accepted Answer

0.5 mmol/hour

Answer

1 mmol/hour

Answer

1.5 mmol/hour

Answer

2.0 mmol/hour

Question 9

Which of the following statements about HIV associated nephropathy (HIVAN) is incorrect?

Accepted Answer

HIVAN is associated with shrunken kidneys.

Answer

HIVAN is characterized by proteinuria.

Answer

HIVAN typically develops when CD4 count is less than 200.

Answer

About 15% of cases show mesangial proliferation.

Question 10

Which of the following is not a typical feature of haemolytic uremic syndrome?

Accepted Answer

Splenomegaly

Answer

Anemia

Answer

Renal microthrombi

Answer

Hyperkalemia

Nephrology — MCQs

Nephrology — MCQs

On this page

Practice by Chapter

Want unlimited practice?