Nephrology — MCQs
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A 28-year-old man presents with recurrent kidney stones. Which serum analysis is essential for determining the metabolic cause of his condition?
A 58-year-old male with diabetes and chronic kidney disease presents with a serum creatinine of 4 mg/dL and a potassium level of 5.9 mEq/L. Which treatment should be avoided due to the potential risk of further increasing potassium levels?
A 70-year-old man presents with generalized weakness and fatigue. Laboratory tests reveal Na+ 130 mEq/L, K+ 5.8 mEq/L, and serum creatinine 2.2 mg/dL. What electrolyte imbalance is most likely present?
A 30-year-old man presents with hematuria and flank pain. A CT scan reveals multiple cysts in both kidneys. His father had a similar condition. What is the most likely diagnosis?
A 55-year-old man with chronic renal failure presents with muscle cramps and bone pain. Laboratory tests show hypocalcemia and hyperphosphatemia. What is the most likely underlying cause?
A 58-year-old female with stage 4 chronic kidney disease, hypertension, and type 2 diabetes mellitus presents with increased fatigue, lower extremity edema, and oliguria. Vital signs show blood pressure of 180/95 and heart rate of 88. Laboratory results indicate elevated creatinine, elevated potassium, decreased bicarbonate, and elevated blood urea nitrogen. Determine the most critical initial management step.
A 72-year-old man presents with new-onset confusion and lethargy. His sodium level is 118 mEq/L. What is the most appropriate initial treatment?
A 65-year-old male with a history of chronic hypertension presents with episodes of dizziness. Which renal mechanism is most likely compensating for his condition?
A 64-year-old male with diabetes mellitus, hypertension, and chronic kidney disease stage 4 presents with hyperkalemia (potassium level 6.8) and an ECG showing peaked T waves. His creatinine level is 4.2. Evaluate and choose the appropriate treatment strategy.
A patient presents with muscle weakness and decreased deep tendon reflexes. Which electrolyte imbalance is most likely the cause?
Nephrology Indian Medical PG Practice Questions and MCQs
Question 741: A 28-year-old man presents with recurrent kidney stones. Which serum analysis is essential for determining the metabolic cause of his condition?
- A. Calcium and phosphate levels (Correct Answer)
- B. Liver function tests
- C. Complete blood count
- D. Serum sodium and potassium levels
Explanation: Detailed metabolic investigation is usually reserved for young patients, those with recurrent or multiple stones, or those with complicated presentations [1]. ***Calcium and phosphate levels*** - Elevated **serum calcium** (hypercalcemia) is a common cause of **calcium oxalate** kidney stones, often due to **primary hyperparathyroidism** [3]. It is estimated that 15% of recurrent stone formers have primary hyperparathyroidism, and the most discriminant investigation is the measurement of PTH [3]. - Abnormal **phosphate levels** can also contribute to stone formation, particularly with certain types of stones like **struvite** (magnesium ammonium phosphate) stones, though often in conjunction with infection [2]. Staghorn calculi fill the whole renal pelvis and are usually associated with infection and composed largely of struvite [2]. *Liver function tests* - **Liver function tests (LFTs)** assess liver health and are generally not directly relevant to the metabolic workup of recurrent kidney stones. - While liver disease can rarely affect metabolic pathways, it is not a primary diagnostic tool for stone etiology. *Complete blood count* - A **complete blood count (CBC)** evaluates for anemia, infection, and other hematological abnormalities, but it does not provide information on the metabolic factors contributing to kidney stone formation. - It might be useful in identifying complications like infection from an obstructed stone, but not the cause of stone formation itself. *Serum sodium and potassium levels* - **Serum electrolytes** like sodium and potassium are crucial for assessing fluid balance and renal tubular function, but they are not primary markers for the metabolic causes of kidney stones. - While electrolyte imbalances can sometimes occur in conditions affecting kidney function [2], they are not typically the initial tests for identifying the underlying metabolic disturbance leading to kidney stones.
Question 742: A 58-year-old male with diabetes and chronic kidney disease presents with a serum creatinine of 4 mg/dL and a potassium level of 5.9 mEq/L. Which treatment should be avoided due to the potential risk of further increasing potassium levels?
- A. Angiotensin-converting enzyme (ACE) inhibitors (Correct Answer)
- B. Calcium channel antagonists
- C. Loop diuretics (e.g., furosemide)
- D. Beta-adrenergic blockers
Explanation: A 58-year-old male with diabetes and chronic kidney disease presents with a serum creatinine of 4 mg/dL and a potassium level of 5.9 mEq/L. Which treatment should be avoided due to the potential risk of further increasing potassium levels? ***Angiotensin-converting enzyme (ACE) inhibitors*** - **ACE inhibitors** can cause **hyperkalemia** by inhibiting **aldosterone** synthesis, leading to decreased potassium excretion in the kidneys [2]. - Given the patient's existing **high potassium level (5.9 mEq/L)** and **chronic kidney disease (CKD)**, an ACE inhibitor would significantly worsen the hyperkalemia [2]. *Calcium channel antagonists* - **Calcium channel antagonists** primarily affect vascular smooth muscle and cardiac conduction; they do **not** directly impact potassium levels [2]. - They are generally considered safe in patients with **CKD** and **hyperkalemia** and do not increase potassium. *Loop diuretics (e.g., furosemide)* - **Loop diuretics** like **furosemide** promote the excretion of potassium (and sodium and water) and are often used to treat **hyperkalemia**, especially in patients with **CKD** [1]. - Therefore, they would likely **lower** or help manage potassium levels, not increase them. *Beta-adrenergic blockers* - While **non-selective beta-blockers** can cause a **minor increase** in potassium by inhibiting cellular potassium uptake via the beta-2 receptor, this effect is usually **clinically insignificant** in normokalemic patients. - They are **less potent** in raising potassium compared to ACE inhibitors, and the primary concern stems from the patient's already elevated potassium and CKD.
Question 743: A 70-year-old man presents with generalized weakness and fatigue. Laboratory tests reveal Na+ 130 mEq/L, K+ 5.8 mEq/L, and serum creatinine 2.2 mg/dL. What electrolyte imbalance is most likely present?
- A. Hyperkalemia (Correct Answer)
- B. Hypokalemia
- C. Hypernatremia
- D. Hyponatremia
Explanation: ### Hyperkalemia - The patient's potassium level is 5.8 mEq/L, which is above the normal range of 3.5-5.0 mEq/L, indicating **hyperkalemia** [1]. - The elevated serum **creatinine (2.2 mg/dL)** suggests **renal insufficiency**, a common cause of hyperkalemia due to impaired potassium excretion [1]. *Hypokalemia* - This condition is characterized by a potassium level below 3.5 mEq/L, which is not consistent with the patient's value of **5.8 mEq/L**. - Renal insufficiency, as indicated by elevated creatinine, typically leads to **potassium retention**, not depletion. *Hypernatremia* - Hypernatremia is defined by a sodium level above 145 mEq/L, whereas the patient's sodium is **130 mEq/L**. - This condition usually results from **dehydration** or excessive sodium intake, neither of which is directly supported by the given lab values for sodium [1]. *Hyponatremia* - While the patient's sodium level of 130 mEq/L is below the normal range (135-145 mEq/L), making **hyponatremia** present, it is not the *most likely* electrolyte imbalance emphasized by the question in the context of the elevated potassium and creatinine [1]. - The prominent finding of severely elevated potassium, coupled with renal failure, makes hyperkalemia the more critical and immediate concern [1].
Question 744: A 30-year-old man presents with hematuria and flank pain. A CT scan reveals multiple cysts in both kidneys. His father had a similar condition. What is the most likely diagnosis?
- A. Autosomal dominant polycystic kidney disease (Correct Answer)
- B. Autosomal recessive polycystic kidney disease
- C. Medullary sponge kidney
- D. Multicystic dysplastic kidney
Explanation: ***Autosomal dominant polycystic kidney disease*** - The presence of **hematuria**, **flank pain**, and **multiple cysts in both kidneys**, along with a family history, is characteristic of autosomal dominant polycystic kidney disease (ADPKD) [1]. - ADPKD often presents in adulthood and is strongly associated with **renal cysts** and **hypertension** due to renal artery involvement [1]. - The cysts can contain clear fluid or brown material from previous hemorrhage, and hemorrhage into cysts may cause sudden pain [1]. *Multicystic dysplastic kidney* - This condition typically affects **one kidney** and results from abnormal kidney development, leading to cysts, often seen in children rather than adults. *Medullary sponge kidney* - Features **cysts within the kidney medulla**, but typically does not involve the entire kidney and does not commonly present with such **systemic symptoms** [2]. - Patients mainly experience **renal stones** and **hematuria**, which is distinct from the more bilateral cystic disease observed here [2]. *Autosomal recessive polycystic kidney disease* - Generally presents in **infancy or early childhood**, with **bilateral enlargement** of the kidneys and liver involvement, rather than in a **30-year-old adult**. - Characterized by different cystic patterns and associated **portal hypertension**, which does not match this presentation.
Question 745: A 55-year-old man with chronic renal failure presents with muscle cramps and bone pain. Laboratory tests show hypocalcemia and hyperphosphatemia. What is the most likely underlying cause?
- A. Primary hyperparathyroidism
- B. Vitamin D deficiency
- C. Secondary hyperparathyroidism (Correct Answer)
- D. Multiple myeloma
Explanation: ***Secondary hyperparathyroidism*** - **Chronic renal failure** leads to impaired **phosphate excretion** and reduced activation of **vitamin D**, both contributing to **hypocalcemia** [1], [3]. - The persistent **hypocalcemia** then stimulates the parathyroid glands to produce excessive parathyroid hormone (**PTH**) [2] in an attempt to normalize calcium levels, resulting in **hyperphosphatemia** and bone pain [3]. *Primary hyperparathyroidism* - This condition is characterized by **hypercalcemia** and **hypophosphatemia** due to autonomous **PTH** secretion from a parathyroid adenoma or hyperplasia [2]. - The patient's presentation of **hypocalcemia** and **hyperphosphatemia** directly contradicts the typical lab findings of primary hyperparathyroidism [1]. *Vitamin D deficiency* - While vitamin D deficiency can cause **hypocalcemia** and bone pain, it typically leads to **hypophosphatemia** as PTH attempts to raise calcium by increasing phosphate excretion [1]. - The presence of **hyperphosphatemia** in this patient makes isolated vitamin D deficiency less likely as the primary cause. *Multiple myeloma* - This hematologic malignancy is primarily associated with **hypercalcemia** due to extensive bone lesions and increased osteoclast activity. - It does not typically present with **hypocalcemia** and **hyperphosphatemia** as seen in this case.
Question 746: A 58-year-old female with stage 4 chronic kidney disease, hypertension, and type 2 diabetes mellitus presents with increased fatigue, lower extremity edema, and oliguria. Vital signs show blood pressure of 180/95 and heart rate of 88. Laboratory results indicate elevated creatinine, elevated potassium, decreased bicarbonate, and elevated blood urea nitrogen. Determine the most critical initial management step.
- A. Hypertensive emergency; initiate IV labetalol
- B. Acute on chronic renal failure; consider dialysis
- C. Volume overload; administer IV furosemide
- D. Hyperkalemia; administer calcium gluconate to stabilize cardiac membranes (Correct Answer)
Explanation: ***Hyperkalemia; administer calcium gluconate to stabilize cardiac membranes*** - The patient presents with **elevated potassium** and symptoms like **fatigue** and **oliguria** in the context of advanced **CKD**, which increases the risk for life-threatening arrhythmias. **Calcium gluconate** provides immediate **cardiac membrane stabilization** without lowering potassium levels [1]. - While other interventions are critical, addressing severe hyperkalemia is an emergent priority to prevent **fatal arrhythmias** and sudden cardiac arrest [1]. *Acute on chronic renal failure; consider dialysis* - This patient likely has **acute on chronic renal failure**, given the worsening symptoms and lab values, but **dialysis** is a more definitive treatment rather than an immediate stabilization measure for the most critical threats. - While dialysis will eventually be needed to correct **electrolyte abnormalities** and fluid overload, stabilizing hyperkalemia takes precedence to prevent immediate cardiac complications [1]. *Hypertensive emergency; initiate IV labetalol* - The patient has **severe hypertension (180/95 mmHg)**, but there are no immediate signs of **end-organ damage** directly attributable to the blood pressure alone that would make hypertensive emergency the absolute first step over hyperkalemia. - Managing blood pressure is important for long-term renal and cardiovascular health [2]; however, **severe hyperkalemia** poses a more immediate threat necessitating priority intervention [1]. *Volume overload; administer IV furosemide* - The patient exhibits signs of **volume overload** (lower extremity edema, oliguria). **Furosemide** could help reduce fluid and indirectly lower potassium, but its effect may be limited in advanced CKD and it does not offer immediate cardiac protection from hyperkalemia. - While volume management is important for comfort and respiratory status, it is secondary to stabilizing immediate cardiac risks posed by severe hyperkalemia.
Question 747: A 72-year-old man presents with new-onset confusion and lethargy. His sodium level is 118 mEq/L. What is the most appropriate initial treatment?
- A. Fluid restriction
- B. Hypertonic saline (Correct Answer)
- C. Isotonic saline
- D. Furosemide
Explanation: ***Hypertonic saline*** - A sodium level of **118 mEq/L** indicates **severe hyponatremia**, which can lead to **cerebral edema** and neurological symptoms like confusion and lethargy. - **Hypertonic saline (3% NaCl)** is the most appropriate initial treatment to rapidly, but carefully, raise the serum sodium level and mitigate these acute life-threatening complications [1]. *Fluid restriction* - While fluid restriction is a common treatment for **mild to moderate euvolemic hyponatremia** (e.g., SIADH), it is too slow and insufficient for **severe, symptomatic hyponatremia** [1]. - Its effects are not rapid enough to address acute neurological symptoms and prevent further neurological deterioration in this critical situation. *Isotonic saline* - **Isotonic saline (0.9% NaCl)** is generally used for **hypovolemic hyponatremia** where volume repletion is needed, but it is not effective for severe symptomatic hyponatremia [1]. - It does not contain enough sodium to significantly raise the serum sodium in a patient with severe hyponatremia and can even worsen it if ADH levels are high. *Furosemide* - **Furosemide** is a loop diuretic that promotes water excretion; however, it is typically used in conjunction with hypertonic saline in cases of **hypervolemic hyponatremia** to prevent fluid overload and facilitate free water excretion. - Using furosemide alone in this setting is inappropriate as it could potentially worsen hyponatremia by promoting natriuresis without adequate sodium replacement, especially if the patient is not hypervolemic.
Question 748: A 65-year-old male with a history of chronic hypertension presents with episodes of dizziness. Which renal mechanism is most likely compensating for his condition?
- A. Suppression of aldosterone release
- B. Stimulation of antidiuretic hormone (ADH) production
- C. Enhanced secretion of atrial natriuretic peptide (ANP) (Correct Answer)
- D. Activation of the renin-angiotensin-aldosterone system (RAAS)
Explanation: ***Enhanced secretion of atrial natriuretic peptide (ANP)*** - **ANP** is a hormone secreted by the **atria** in response to **atrial stretch** caused by increased blood volume or pressure, such as in chronic hypertension [1]. - Its primary role is to promote **natriuresis** (sodium excretion) and **diuresis** (water excretion), thereby reducing blood volume and blood pressure which can help alleviate dizziness caused by hypertension [1], [2]. *Suppression of aldosterone release* - Aldosterone normally promotes **sodium and water retention**, which would exacerbate hypertension [3]. - While ANP does suppress aldosterone, the direct compensatory mechanism to reduce blood pressure is the ANP release itself, not solely the suppression of aldosterone. *Stimulation of antidiuretic hormone (ADH) production* - **ADH** primarily promotes **water reabsorption** in the kidneys, leading to increased blood volume and potentially higher blood pressure [4]. - This mechanism would counteract the goal of reducing blood pressure in a hypertensive patient and is not a compensatory response for chronic hypertension [4]. *Activation of the renin-angiotensin-aldosterone system (RAAS)* - The **RAAS** is a system that ultimately leads to **vasoconstriction** and **sodium/water retention**, both of which increase blood pressure [3]. - Activation of RAAS would worsen hypertension and is considered a contributing factor to the condition, not a compensatory mechanism to alleviate it [1].
Question 749: A 64-year-old male with diabetes mellitus, hypertension, and chronic kidney disease stage 4 presents with hyperkalemia (potassium level 6.8) and an ECG showing peaked T waves. His creatinine level is 4.2. Evaluate and choose the appropriate treatment strategy.
- A. IV calcium gluconate, insulin + glucose, consider dialysis (Correct Answer)
- B. Oral sodium polystyrene sulfonate, loop diuretics
- C. Sodium bicarbonate, monitor potassium closely
- D. Increase dialysis frequency, continue ACE inhibitors
Explanation: ***IV calcium gluconate, insulin + glucose, consider dialysis*** - **Intravenous calcium gluconate** provides immediate cardiac membrane stabilization, counteracting the arrhythmogenic effects of hyperkalemia [1]. - **Insulin and glucose** shift potassium intracellularly, rapidly lowering serum potassium levels, and in this patient with severe hyperkalemia and CKD, dialysis is indicated for definitive potassium removal [1]. *Oral sodium polystyrene sulfonate, loop diuretics* - **Sodium polystyrene sulfonate** takes hours to days to act and is not suitable for acute, severe hyperkalemia with ECG changes. - **Loop diuretics** alone are insufficient to manage severe hyperkalemia in a patient with CKD stage 4 due to significantly impaired renal function. *Sodium bicarbonate, monitor potassium closely* - **Sodium bicarbonate** can shift potassium intracellularly, but its effect is slower and less reliable than insulin/glucose, especially in non-acidotic patients. - Simply monitoring potassium closely without aggressive intervention is inappropriate for **severe hyperkalemia** with ECG changes [1]. *Increase dialysis frequency, continue ACE inhibitors* - While increasing dialysis frequency is a long-term management strategy for CKD with recurrent hyperkalemia, it does not address the acute, life-threatening hyperkalemia. - **ACE inhibitors** are a common cause of hyperkalemia in patients with CKD and should be discontinued or held in the setting of acute, severe hyperkalemia, and not continued.
Question 750: A patient presents with muscle weakness and decreased deep tendon reflexes. Which electrolyte imbalance is most likely the cause?
- A. Hyperkalemia
- B. Hypokalemia (Correct Answer)
- C. Hypernatremia
- D. Hyponatremia
Explanation: ***Hypokalemia*** - **Muscle weakness** and **decreased deep tendon reflexes** are classic symptoms of **hypokalemia**, as low potassium levels interfere with normal muscle cell excitability [1]. - Severe hypokalemia can lead to **paralysis** and life-threatening **cardiac arrhythmias**. *Hyperkalemia* - While hyperkalemia can also cause muscle weakness, it generally presents with **increased irritability** of muscle tissue [1], often leading to **paresthesias** and, in severe cases, flaccid paralysis. - Deep tendon reflexes are usually preserved or can even be hyperactive until very late stages. *Hypernatremia* - **Hypernatremia** is primarily associated with **neurological symptoms** due to brain cell shrinkage, such as altered mental status, lethargy, and seizures [1]. *Hyponatremia* - **Hyponatremia** also mainly presents with **neurological symptoms** like headache, confusion, and seizures, due to brain cell swelling [2]. - While severe cases can cause muscle cramps or weakness as a secondary effect, it is not the primary cause of widespread muscle weakness and decreased deep tendon reflexes.
Practice by Chapter
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