All questions
Question 1
A 68-year-old man with a 20-year history of type 2 diabetes mellitus and hypertension presents for a routine follow-up. His medications include metformin, lisinopril, and atorvastatin. His blood pressure is 135/85 mm Hg. Laboratory studies show a serum creatinine of 2.0 mg/dL. Three months ago, his creatinine was 1.9 mg/dL. A 24-hour urine collection shows 500 mg of albumin. His estimated glomerular filtration rate (eGFR) is calculated to be 35 mL/min/1.73 m².
According to the Kidney Disease: Improving Global Outcomes (KDIGO) guidelines, which of the following is the most accurate classification of this patient's chronic kidney disease?
- Stage G2 A2
- Stage G3a A1
- Stage G3b A3 (correct answer)
- Stage G4 A2
Explanation: The correct answer is C. Chronic kidney disease (CKD) staging is based on both the glomerular filtration rate (GFR) and albuminuria levels. The GFR stages are: G1 (>90), G2 (60-89), G3a (45-59), G3b (30-44), G4 (15-29), and G5 (<15). The albuminuria stages are: A1 (<30 mg/day), A2 (30-300 mg/day), and A3 (>300 mg/day). This patient's eGFR of 35 mL/min/1.73 m² places him in stage G3b. His albuminuria of 500 mg/day places him in stage A3. Therefore, his CKD classification is G3b A3.
Question 2
A 55-year-old woman with stage 4 chronic kidney disease due to autosomal dominant polycystic kidney disease is brought to the emergency department for evaluation of generalized weakness and palpitations. An ECG is obtained and shows peaked T waves and a widened QRS complex. Her medications include lisinopril and sevelamer.
Which of the following is the most appropriate immediate step in the management of this patient?
- Administer intravenous insulin and glucose
- Administer intravenous calcium gluconate (correct answer)
- Administer oral sodium polystyrene sulfonate
- Arrange for urgent hemodialysis
Explanation: The correct answer is B. The patient's symptoms and ECG findings (peaked T waves, widened QRS) are highly suggestive of severe hyperkalemia, a common complication of advanced CKD. The most important immediate step is to stabilize the cardiac membrane to prevent life-threatening arrhythmias. Intravenous calcium gluconate is the first-line agent for cardiac membrane stabilization and does not lower the serum potassium level. After stabilizing the membrane, therapies to shift potassium intracellularly (A - insulin and glucose) and remove it from the body (C, D) should be initiated. Urgent hemodialysis (D) is definitive treatment but is not the most immediate step. Sodium polystyrene sulfonate (C) is slow-acting and not appropriate for acute, life-threatening hyperkalemia.
Question 3
A 58-year-old man with end-stage renal disease secondary to diabetic nephropathy is being evaluated for renal replacement therapy. His eGFR is 12 mL/min/1.73 m². He feels generally well but reports decreased appetite and occasional morning nausea. He has been adherent to his dietary and fluid restrictions. He is interested in a home-based therapy option. He has a history of three prior laparotomies for small bowel obstruction secondary to adhesions.
Which of the following is the most appropriate recommendation regarding preparation for renal replacement therapy for this patient?
- Placement of a peritoneal dialysis catheter
- Creation of a forearm arteriovenous fistula (correct answer)
- Insertion of a tunneled hemodialysis catheter
- Continue medical management and reassess in 6 months
Explanation: The correct answer is B. This patient's GFR is approaching the level where renal replacement therapy (RRT) is typically initiated (<10-15 mL/min/1.73 m²). Preparation should begin well in advance. The preferred long-term access for hemodialysis is an arteriovenous (AV) fistula due to its lower rates of infection and thrombosis and superior longevity. Given his interest in RRT, referral for AV fistula creation is the most appropriate next step. Peritoneal dialysis (A) is a home-based option but is relatively contraindicated in this patient due to his history of multiple abdominal surgeries, which increases the risk of catheter dysfunction and peritonitis. A tunneled catheter (C) is a less preferred option for long-term access due to high infection rates and should only be used if an AV fistula or graft is not possible. Delaying planning (D) is inappropriate given his low GFR and early uremic symptoms.
Question 4
A 67-year-old man with stage 4 chronic kidney disease presents for follow-up. His eGFR is 28 mL/min/1.73 m². Laboratory testing reveals a serum bicarbonate level of 18 mEq/L (Normal: 22-28). He is asymptomatic. His other electrolytes are within normal limits. His blood pressure is 130/80 mm Hg on lisinopril and amlodipine.
In addition to slowing the progression of his kidney disease, what is the primary benefit of initiating oral sodium bicarbonate therapy for this patient?
- Improving serum potassium levels
- Reducing cardiovascular mortality
- Preventing bone demineralization (correct answer)
- Increasing hemoglobin concentration
Explanation: The correct answer is C. Patients with CKD often develop a chronic metabolic acidosis due to the kidneys' inability to excrete the daily acid load. This chronic acidemia has several detrimental effects, most notably acting as a buffer system by mobilizing calcium carbonate from bone, leading to bone demineralization and worsening CKD-MBD. Correcting the acidosis with oral sodium bicarbonate can prevent this process. While treating acidosis has been associated with slowing CKD progression and may have other benefits, its most direct and well-established effect is on bone health. It does not directly improve potassium (A), although severe acidosis can worsen hyperkalemia. Effects on cardiovascular mortality (B) or hemoglobin (D) are less direct.
Question 5
A 66-year-old man with end-stage renal disease on hemodialysis complains of severe joint pain in his shoulder that limits his range of motion. He has also noticed carpal tunnel syndrome symptoms. Physical examination is unremarkable. An X-ray of the shoulder is ordered and shows lytic bone lesions and juxta-articular erosions.
This patient's condition is most likely caused by the deposition of which of the following substances?
- Calcium pyrophosphate
- Monosodium urate
- Beta-2 microglobulin (correct answer)
- Hydroxyapatite
Explanation: The correct answer is C. This patient's presentation is classic for dialysis-related amyloidosis, which is caused by the deposition of beta-2 microglobulin in osteoarticular structures. Beta-2 microglobulin is a medium-sized molecule that is not effectively cleared by conventional hemodialysis membranes, leading to its accumulation over years of treatment. It commonly affects the shoulders, hips, and wrists, causing arthropathy, bone cysts, and carpal tunnel syndrome. Calcium pyrophosphate (A) causes pseudogout. Monosodium urate (B) causes gout, which is common in CKD but has a different clinical and radiographic appearance. Hydroxyapatite (D) deposition can occur but is less likely to cause this specific syndrome.
Question 6
A 59-year-old man with stage 5 chronic kidney disease who is not yet on dialysis is brought to the emergency department with altered mental status. His wife reports he has been increasingly confused and lethargic over the past day and had an episode of vomiting this morning. On examination, he is somnolent but arousable. A friction rub is auscultated over the precordium. His eGFR is 8 mL/min/1.73 m².
Which of the following is the most appropriate next step in management?
- Administer high-dose NSAIDs
- Perform pericardiocentesis
- Initiate urgent hemodialysis (correct answer)
- Administer intravenous corticosteroids
Explanation: The correct answer is C. This patient is presenting with signs and symptoms of severe uremia, including encephalopathy (altered mental status) and pericarditis (pericardial friction rub). Uremic pericarditis is an absolute indication for the initiation of renal replacement therapy. Urgent hemodialysis is required to remove the uremic toxins and prevent progression to cardiac tamponade. High-dose NSAIDs (A) or corticosteroids (D) are used for viral or idiopathic pericarditis but are ineffective and potentially harmful (NSAIDs are nephrotoxic) in uremic pericarditis. Pericardiocentesis (B) is only indicated if there is evidence of cardiac tamponade (e.g., hypotension, pulsus paradoxus, jugular venous distention), which is not described here.
Question 7
A 60-year-old woman with stage 4 CKD has persistent hyperphosphatemia despite dietary counseling. Her corrected calcium is 8.8 mg/dL and her PTH is elevated. The decision is made to start a phosphate binder. She has a history of coronary artery disease with calcification noted on a prior CT scan.
Which of the following is the most appropriate initial choice for a phosphate binder in this patient?
- Calcium carbonate
- Sevelamer hydrochloride (correct answer)
- Aluminum hydroxide
- Magnesium hydroxide
Explanation: The correct answer is B. In patients with CKD and known vascular or soft tissue calcification, non-calcium-based phosphate binders are preferred over calcium-based binders. Sevelamer (a non-absorbable polymer) and lanthanum are first-line non-calcium-based options. Calcium-based binders like calcium carbonate (A) can contribute to a positive calcium balance and may worsen vascular calcification. Aluminum hydroxide (C) is a potent phosphate binder but is avoided for long-term use due to the risk of aluminum toxicity (adynamic bone disease, encephalopathy). Magnesium-containing binders (D) are generally avoided in CKD due to the risk of hypermagnesemia.
Question 8
A 52-year-old man with autosomal dominant polycystic kidney disease has progressed to stage 5 CKD with an eGFR of 10 mL/min/1.73 m². He has significant fatigue, poor appetite, and has lost 5 kg over the past 6 months. He is normotensive and his electrolytes are stable on medical therapy. He is being counseled on the timing of initiating renal replacement therapy.
Which of the following is the strongest indication to initiate dialysis in this patient?
- eGFR less than 15 mL/min/1.73 m²
- Presence of large renal cysts
- Uncontrolled hypertension
- Severe uremic symptoms (correct answer)
Explanation: The correct answer is D. The decision to initiate dialysis is primarily a clinical one, based on the presence of signs and symptoms of uremia that are refractory to medical management, rather than a specific GFR number. This patient's significant fatigue, anorexia, and weight loss (failure to thrive) are severe uremic symptoms that constitute a clear indication to begin dialysis. While most patients start dialysis with an eGFR between 5-15 mL/min/1.73 m² (A), the GFR value itself is not an absolute indication. The presence of cysts (B) is the underlying disease, not an indication for dialysis. His blood pressure is controlled (C).
Question 9
A 48-year-old man with end-stage renal disease secondary to IgA nephropathy has been on hemodialysis for 8 years. He presents with bone pain. Laboratory studies reveal a serum calcium of 11.2 mg/dL (Normal: 8.5-10.2), phosphorus of 5.0 mg/dL (Normal: 2.5-4.5), and an intact PTH level of 2000 pg/mL (Normal: 15-65). A parathyroid scan shows enlargement of all four glands.
This clinical picture is most consistent with which of the following conditions?
- Primary hyperparathyroidism
- Secondary hyperparathyroidism
- Tertiary hyperparathyroidism (correct answer)
- Adynamic bone disease
Explanation: The correct answer is C. This patient has tertiary hyperparathyroidism, a complication of long-standing secondary hyperparathyroidism in patients with ESRD. Chronic stimulation of the parathyroid glands (from hypocalcemia and hyperphosphatemia) leads to hyperplastic, autonomous glands that secrete very high levels of PTH regardless of serum calcium levels. This results in hypercalcemia, which distinguishes it from secondary hyperparathyroidism (B), where calcium is typically low or normal. Primary hyperparathyroidism (A) is not related to CKD and usually involves a single adenoma. Adynamic bone disease (D) is characterized by very low PTH levels and low bone turnover.
Question 10
A 65-year-old man is diagnosed with chronic kidney disease. His medical history is significant for benign prostatic hyperplasia and recurrent kidney stones. A renal ultrasound shows moderate bilateral hydronephrosis and a thickened bladder wall. His post-void residual volume is 300 mL. His creatinine has been slowly increasing over the past two years.
The pathogenesis of this patient's chronic kidney disease is most likely related to which of the following?
- Glomerular immune complex deposition
- Ischemic injury from hypertension
- Chronic tubulointerstitial inflammation
- Increased hydrostatic pressure in Bowman's space (correct answer)
Explanation: The correct answer is D. This patient's clinical picture is consistent with obstructive uropathy secondary to BPH. Chronic obstruction of urine outflow leads to increased pressure in the ureters and renal pelves (hydronephrosis). This pressure is transmitted proximally to the Bowman's space within the glomerulus. The elevated hydrostatic pressure in Bowman's space opposes the pressure driving glomerular filtration, leading to a decrease in GFR. Over time, this sustained pressure causes tubulointerstitial fibrosis and progressive chronic kidney disease. Glomerular deposition (A), hypertensive injury (B), and primary tubulointerstitial inflammation (C) are other causes of CKD but do not fit the obstructive picture presented.
Question 11
A 64-year-old man with stage 4 chronic kidney disease (eGFR 25 mL/min/1.73 m²) is noted to have a normocytic, normochromic anemia with a hemoglobin of 9.2 g/dL. His blood pressure is well-controlled. Further laboratory studies are obtained.
Ferritin: 150 ng/mL
Transferrin saturation (TSAT): 25%
Vitamin B12: 450 pg/mL
Folate: 12 ng/mL
Stool guaiac: Negative
Which of the following is the most appropriate next step in the management of this patient's anemia?
- Initiate oral iron sulfate supplementation
- Administer a transfusion of packed red blood cells
- Initiate therapy with an erythropoiesis-stimulating agent (correct answer)
- Refer for bone marrow biopsy
Explanation: The correct answer is C. Anemia of chronic kidney disease is primarily caused by decreased production of erythropoietin by the failing kidneys. Before initiating therapy with an erythropoiesis-stimulating agent (ESA), it is essential to ensure adequate iron stores, as iron is a necessary substrate for erythropoiesis. This patient's ferritin (>100 ng/mL) and TSAT (>20%) indicate adequate iron stores. Therefore, the most appropriate next step is to initiate an ESA like epoetin alfa or darbepoetin alfa. Oral iron (A) is not indicated as his stores are replete. Blood transfusion (B) is reserved for severe, symptomatic anemia or acute hemorrhage. A bone marrow biopsy (D) is not indicated as the cause of anemia is clear.
Question 12
A 75-year-old man with chronic kidney disease, hypertension, and coronary artery disease is started on an erythropoiesis-stimulating agent (ESA) for anemia of CKD. His hemoglobin level is monitored closely. The goal is to titrate the dose to a target hemoglobin level.
Targeting a hemoglobin level greater than 11.5 g/dL with an ESA in this patient population has been associated with an increased risk of which of the following?
- Hypotension
- Thromboembolic events (correct answer)
- Hypokalemia
- Gastrointestinal bleeding
Explanation: The correct answer is B. Large clinical trials have shown that using ESAs to target higher hemoglobin levels (>11.5-12 g/dL) in patients with CKD is associated with an increased risk of adverse cardiovascular events, including myocardial infarction, stroke, and venous thromboembolism. Higher hemoglobin levels increase blood viscosity and may promote a prothrombotic state. Therefore, current guidelines recommend a target hemoglobin of 10-11.5 g/dL. Hypertension, not hypotension (A), is a common side effect of ESA therapy. ESAs do not directly cause hypokalemia (C) or GI bleeding (D).
Question 13
A 62-year-old woman with chronic kidney disease (baseline creatinine 2.5 mg/dL) is hospitalized for community-acquired pneumonia. She is treated with intravenous antibiotics. On day 3 of admission, her serum creatinine rises to 4.0 mg/dL. Urinalysis reveals 1+ protein, white blood cells, and numerous white blood cell casts. Urine eosinophils are present. She denies any flank pain or urinary symptoms.
The addition of which of the following medications is the most likely cause of this patient's worsening kidney function?
- Vancomycin
- Azithromycin
- Piperacillin-tazobactam (correct answer)
- Ceftriaxone
Explanation: The correct answer is C. This patient's presentation of acute kidney injury with sterile pyuria (WBCs without bacteria), WBC casts, and eosinophiluria is classic for acute interstitial nephritis (AIN). Beta-lactam antibiotics, particularly penicillins like piperacillin-tazobactam, are among the most common causes of drug-induced AIN through a type IV hypersensitivity reaction. The presence of urine eosinophils strongly suggests an allergic mechanism. Vancomycin (A) more commonly causes acute tubular necrosis with muddy brown casts rather than AIN. Azithromycin (B) and ceftriaxone (D) are less frequently associated with AIN compared to penicillins.
Question 14
A 72-year-old man is evaluated for a progressively rising serum creatinine level over the past 5 years. He has a 30-year history of hypertension, which has been reasonably controlled with hydrochlorothiazide and amlodipine. He denies any history of diabetes, autoimmune disease, or recent use of NSAIDs. Physical examination reveals a blood pressure of 145/90 mm Hg and trace bilateral pedal edema. Urinalysis is bland, showing no cells, casts, or protein. Renal ultrasound shows bilaterally small, echogenic kidneys without hydronephrosis.
Which of the following is the most likely etiology of this patient's chronic kidney disease?
- Diabetic nephropathy
- Hypertensive nephrosclerosis (correct answer)
- Polycystic kidney disease
- Chronic glomerulonephritis
Explanation: The correct answer is B. This patient's long-standing history of hypertension, combined with a bland urinalysis (no proteinuria, cells, or casts) and findings of small, echogenic kidneys on ultrasound, is classic for hypertensive nephrosclerosis. This is a diagnosis of exclusion after ruling out other causes. Diabetic nephropathy (A) is unlikely as he has no history of diabetes and would typically present with significant proteinuria. Polycystic kidney disease (C) would present with large, cystic kidneys on ultrasound. Chronic glomerulonephritis (D) would typically be associated with an active urine sediment (hematuria, red cell casts) and significant proteinuria.
Question 15
A 71-year-old woman with stage 5 CKD (eGFR 13 mL/min/1.73 m²) is evaluated. She has had a poor appetite for several months and reports a metallic taste in her mouth and frequent episodes of nausea, particularly in the morning. She has no other complaints. Her physical exam is unremarkable. Laboratory results are stable.
This patient's symptoms are most likely a manifestation of which of the following?
- Anemia
- Gastroparesis
- Uremia (correct answer)
- Hyperkalemia
Explanation: The correct answer is C. The constellation of symptoms including anorexia, nausea, vomiting, and a metallic taste (dysgeusia) are classic early gastrointestinal manifestations of uremia. These symptoms are caused by the accumulation of uremic toxins that are normally cleared by the kidneys. While she may also have anemia (A) causing fatigue, it does not typically cause dysgeusia or nausea. Gastroparesis (B) can occur, especially in diabetics, but the full symptom complex is more suggestive of uremia. Hyperkalemia (D) typically presents with weakness, palpitations, or arrhythmias, not these GI symptoms.
Question 16
A 45-year-old woman with a 15-year history of systemic lupus erythematosus presents with worsening peripheral edema and fatigue. Her blood pressure is 160/100 mm Hg. Laboratory studies show a serum creatinine of 2.8 mg/dL and a serum albumin of 2.5 g/dL. Urinalysis reveals 4+ proteinuria and red blood cell casts.
Which of the following is the most likely cause of this patient's chronic kidney disease?
- IgA nephropathy
- Membranous nephropathy
- Lupus nephritis (correct answer)
- Hypertensive nephrosclerosis
Explanation: The correct answer is C. This patient's history of systemic lupus erythematosus (SLE) combined with a nephritic picture (hypertension, rising creatinine, hematuria with RBC casts) and nephrotic-range proteinuria (4+, low serum albumin) is highly suggestive of lupus nephritis. Lupus nephritis is a common and serious complication of SLE caused by immune complex deposition in the glomeruli. IgA nephropathy (A) is less common in this demographic and typically presents with episodic gross hematuria. Membranous nephropathy (B) is a cause of nephrotic syndrome but is less likely to have such an active urinary sediment with RBC casts. While she has hypertension, hypertensive nephrosclerosis (D) would not cause an active urinary sediment or nephrotic-range proteinuria.
Question 17
A 78-year-old woman with stage 4 CKD (eGFR 22 mL/min/1.73 m²) is hospitalized for a hip fracture. Post-operatively, she develops atrial fibrillation with a rapid ventricular response. Her blood pressure is 105/60 mm Hg. The medical team plans to start anticoagulation for stroke prevention.
Which of the following anticoagulants is generally contraindicated in patients with an eGFR below 30 mL/min/1.73 m²?
- Warfarin
- Apixaban
- Rivaroxaban (correct answer)
- Heparin
Explanation: The correct answer is C. Many direct oral anticoagulants (DOACs) are cleared by the kidneys and require dose adjustment or are contraindicated in severe CKD. Rivaroxaban is contraindicated in patients with a creatinine clearance less than 30 mL/min for the treatment of non-valvular atrial fibrillation. Apixaban (B) can be used with caution, typically at a reduced dose, in patients with severe CKD and those on dialysis. Warfarin (A) is not renally cleared and can be used in CKD, although it requires close monitoring and may increase the risk of vascular calcification. Heparin (D) can also be used in patients with severe CKD.
Question 18
A 69-year-old man with long-standing, poorly controlled type 2 diabetes mellitus and an eGFR of 40 mL/min/1.73 m² is seen for routine follow-up. He is on an appropriate dose of an ACE inhibitor. His blood pressure is 138/84 mm Hg and his HbA1c is 8.5%. His urinalysis shows 3+ proteinuria. His physician is considering adding another agent to his regimen.
Which of the following medication classes has been shown to slow the progression of chronic kidney disease in patients with diabetes, independent of its effects on blood glucose?
- Sulfonylureas
- Dipeptidyl peptidase-4 (DPP-4) inhibitors
- Sodium-glucose cotransporter-2 (SGLT-2) inhibitors (correct answer)
- Thiazolidinediones
Explanation: The correct answer is C. SGLT-2 inhibitors (e.g., empagliflozin, canagliflozin) have demonstrated significant renal benefits in patients with diabetic kidney disease. They reduce intraglomerular pressure by causing afferent arteriolar constriction (via tubuloglomerular feedback) and have anti-inflammatory and anti-fibrotic effects. These benefits lead to a reduction in albuminuria and a slowing of GFR decline, independent of their glucose-lowering effect. Sulfonylureas (A), DPP-4 inhibitors (B), and thiazolidinediones (D) do not have this primary renal-protective effect, although glycemic control in general is important for preventing CKD progression.
Question 19
A 70-year-old woman with stage 5 chronic kidney disease (eGFR 14 mL/min/1.73 m²) presents with fatigue, bone pain, and pruritus. Laboratory studies show:
Calcium: 8.2 mg/dL (Normal: 8.5-10.2)
Phosphorus: 6.5 mg/dL (Normal: 2.5-4.5)
Intact parathyroid hormone (PTH): 850 pg/mL (Normal: 15-65)
Alkaline phosphatase: 250 U/L (Normal: 44-147)
These findings are most consistent with which of the following complications of chronic kidney disease?
- Adynamic bone disease
- Secondary hyperparathyroidism (correct answer)
- Tertiary hyperparathyroidism
- Osteomalacia
Explanation: The correct answer is B. The combination of hypocalcemia, hyperphosphatemia, and a markedly elevated PTH level is characteristic of secondary hyperparathyroidism, a common component of CKD-Mineral and Bone Disorder (CKD-MBD). In CKD, decreased phosphate excretion leads to hyperphosphatemia. The failing kidney also cannot produce enough active vitamin D (calcitriol), leading to decreased intestinal calcium absorption and hypocalcemia. Both hyperphosphatemia and hypocalcemia stimulate the parathyroid glands to produce excess PTH. Adynamic bone disease (A) is characterized by low PTH levels. Tertiary hyperparathyroidism (C) involves autonomous PTH secretion, leading to hypercalcemia. Osteomalacia (D) is caused by vitamin D deficiency and would present with hypocalcemia and hypophosphatemia.
Question 20
A 35-year-old man with end-stage renal disease is preparing to start renal replacement therapy. He works as a freelance writer from home and values his independence and flexible schedule. He is otherwise healthy, with no history of abdominal surgeries, and has good manual dexterity and vision. He wants to minimize trips to a medical center.
Given this patient's clinical and social situation, which of the following is the most suitable modality of renal replacement therapy?
- In-center hemodialysis
- Peritoneal dialysis (correct answer)
- Kidney transplantation from a deceased donor
- Nocturnal home hemodialysis
Explanation: The correct answer is B. Peritoneal dialysis (PD) is a home-based therapy that allows for greater flexibility and independence compared to in-center hemodialysis. The patient performs exchanges himself, typically overnight with a cycler machine (automated PD) or manually during the day (continuous ambulatory PD). This patient's desire for independence, flexible schedule, lack of contraindications (e.g., abdominal adhesions), and good physical capacity make him an ideal candidate for PD. In-center hemodialysis (A) requires travel to a center 3 times a week. Nocturnal home hemodialysis (D) is an option but is more complex and requires a trained partner. Kidney transplantation (C) is the ultimate goal but is a treatment, not a dialysis modality, and there is a significant waiting time for a deceased donor organ.