Nephrology Practice Questions

Q: A 28-year-old man presents with recurrent kidney stones. Which serum analysis is essential for determining the metabolic cause of his condition?

Calcium and phosphate levels. 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.

Q: 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. 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.

Q: 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?

Autosomal dominant polycystic kidney disease. ***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.

Q: 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?

Hyperkalemia. ### 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].

Q: 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?

Secondary hyperparathyroidism. ***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.

Q: 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?

Hypertonic saline. ***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.

Q: 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.

IV calcium gluconate, insulin + glucose, consider dialysis. ***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.

Q: A patient presents with muscle weakness and decreased deep tendon reflexes. Which electrolyte imbalance is most likely the cause?

Hypokalemia. ***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.

Q: In a patient with chronic kidney disease, what is the primary reason for choosing an ARB over an ACE inhibitor for managing proteinuria?

ARB; better tolerated in patients with renal impairment. ARB; better tolerated in patients with renal impairment - Angiotensin receptor blockers (ARBs) are often preferred in patients with chronic kidney disease (CKD) due to a lower incidence of side effects, particularly chronic cough, compared to ACE inhibitors [1]. - This improved tolerability often leads to better patient adherence and sustained treatment for proteinuria management, which is crucial in CKD. ARB; lower risk of adverse effects in renal impairment - While ARBs have a lower incidence of certain side effects like cough compared to ACE inhibitors, both drug classes carry similar risks for other adverse effects in renal impairment, such as hyperkalemia and acute kidney injury [2]. - The primary differentiator is often the prevention of cough and angioedema, leading to better overall tolerability rather than a universally lower risk of *all* adverse effects. ACE inhibitor; more effective at reducing proteinuria in all patients - ACE inhibitors and ARBs are considered equally effective at reducing proteinuria in most patients with CKD by blocking the renin-angiotensin-aldosterone system (RAAS) [2]. - The choice between them in CKD is often driven by tolerability issues rather than superior antiproteinuric efficacy of one over the other [1]. ACE inhibitor; reduces blood pressure more effectively in chronic kidney disease - Both ACE inhibitors and ARBs are highly effective at reducing blood pressure in patients with CKD, which is a critical aspect of kidney protection [2]. - There is no substantial evidence to suggest that ACE inhibitors are inherently more effective than ARBs at lowering blood pressure in this patient population.

Question 1

A 28-year-old man presents with recurrent kidney stones. Which serum analysis is essential for determining the metabolic cause of his condition?

Accepted Answer

Calcium and phosphate levels

Answer

Liver function tests

Answer

Complete blood count

Answer

Serum sodium and potassium levels

Question 2

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?

Accepted Answer

Angiotensin-converting enzyme (ACE) inhibitors

Answer

Calcium channel antagonists

Answer

Loop diuretics (e.g., furosemide)

Answer

Beta-adrenergic blockers

Question 3

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?

Accepted Answer

Autosomal dominant polycystic kidney disease

Answer

Autosomal recessive polycystic kidney disease

Answer

Medullary sponge kidney

Answer

Multicystic dysplastic kidney

Question 4

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?

Accepted Answer

Hyperkalemia

Answer

Hypokalemia

Answer

Hypernatremia

Answer

Hyponatremia

Question 5

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?

Accepted Answer

Secondary hyperparathyroidism

Answer

Primary hyperparathyroidism

Answer

Vitamin D deficiency

Answer

Multiple myeloma

Question 6

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?

Accepted Answer

Hypertonic saline

Answer

Fluid restriction

Answer

Isotonic saline

Answer

Furosemide

Question 7

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.

Accepted Answer

Hyperkalemia; administer calcium gluconate to stabilize cardiac membranes

Answer

Hypertensive emergency; initiate IV labetalol

Answer

Acute on chronic renal failure; consider dialysis

Answer

Volume overload; administer IV furosemide

Question 8

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.

Accepted Answer

IV calcium gluconate, insulin + glucose, consider dialysis

Answer

Oral sodium polystyrene sulfonate, loop diuretics

Answer

Sodium bicarbonate, monitor potassium closely

Answer

Increase dialysis frequency, continue ACE inhibitors

Question 9

A patient presents with muscle weakness and decreased deep tendon reflexes. Which electrolyte imbalance is most likely the cause?

Accepted Answer

Hypokalemia

Answer

Hyperkalemia

Answer

Hypernatremia

Answer

Hyponatremia

Question 10

In a patient with chronic kidney disease, what is the primary reason for choosing an ARB over an ACE inhibitor for managing proteinuria?

Accepted Answer

ARB; better tolerated in patients with renal impairment

Answer

ARB; lower risk of adverse effects in renal impairment

Answer

ACE inhibitor; more effective at reducing proteinuria in all patients

Answer

ACE inhibitor; reduces blood pressure more effectively in chronic kidney disease

Nephrology — MCQs

Nephrology — MCQs

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