Mock Nephrology Module 3

A 58-year-old man with end-stage kidney disease (ESKD) secondary to diabetic nephropathy has been on peritoneal dialysis (PD) for 3 years.

His nephrologist notes that his clearance of middle molecules (molecular weight 500–60,000 Da) is relatively preserved compared to a matched patient on conventional haemodialysis.

Which of the following best explains this observation?

A 45-year-old woman presents to the emergency department with a 4-week history of progressive lethargy, nausea, and confusion.

Investigations reveal:

• serum urea of 55 mmol/L (reference range 3.0–8.0 mmol/L)
• creatinine 1,850 µmol/L (reference range 45–90 µmol/L)
• potassium 7.2 mmol/L (reference range 3.5–5.0 mmol/L)
• bicarbonate 8 mmol/L (reference range 22–32 mmol/L)

She is commenced on urgent haemodialysis. Thirty minutes into her first session, she develops a severe headache, vomiting, and becomes increasingly agitated.

Which of the following is the most likely mechanism for her symptoms?

A 62-year-old man with ESKD secondary to IgA nephropathy is referred for creation of haemodialysis access.

His estimated GFR is 12 mL/min/1.73m² and is declining steadily.

He is right-hand dominant. He has no significant peripheral vascular disease and has adequate forearm veins bilaterally on ultrasound assessment.

Which of the following is the most appropriate initial vascular access?

A 50-year-old woman on continuous ambulatory peritoneal dialysis (CAPD) for 18 months presents with abdominal pain and cloudy PD effluent.

Her peritoneal fluid cell count shows 450 white cells/µL (reference: <100/µL) with 85% neutrophils.

Gram stain reveals gram-positive cocci in clusters. Empirical intraperitoneal antibiotics are commenced. Cultures subsequently grow methicillin-sensitive Staphylococcus aureus.

She has had one previous episode of peritonitis 6 months ago caused by coagulase-negative staphylococci.

Which of the following is the most important next step in management?

A 55-year-old man has been on CAPD for 2 years for ESKD secondary to autosomal dominant polycystic kidney disease. He is gaining weight and becoming increasingly fluid overloaded despite using 2.5% glucose dialysate for all four daily exchanges.

A peritoneal equilibration test (PET) is performed. The 4-hour dialysate-to-plasma creatinine ratio (D/P Cr) is 0.85.

Which of the following best describes his membrane transport type and the most appropriate modification to his PD prescription?

A 72-year-old woman with known CKD stage 4 (baseline eGFR 22 mL/min/1.73m²) secondary to hypertensive nephrosclerosis presents with 5 days of diarrhoea and vomiting.

Investigations reveal:

• sodium 130 mmol/L (reference 135–145)
• potassium 7.8 mmol/L (reference 3.5–5.0)
• bicarbonate 10 mmol/L (reference 22–32)
• urea 42 mmol/L (reference 3.0–8.0)
• creatinine 680 µmol/L (reference 45–90)
• eGFR 5 mL/min/1.73m²

An ECG shows tall peaked T waves and widened QRS complexes.

She has received intravenous calcium gluconate, insulin-dextrose, and salbutamol nebulisers, but her potassium remains 7.2 mmol/L on repeat testing.

Which of the following is the most appropriate next step?

A 68-year-old man with ESKD secondary to type 2 diabetic nephropathy is being followed in a pre-dialysis clinic. His current eGFR is 8 mL/min/1.73m².

He reports mild fatigue but is otherwise asymptomatic, with a stable weight, good appetite, and no evidence of fluid overload.

His potassium is 5.1 mmol/L (reference 3.5–5.0), bicarbonate 20 mmol/L (reference 22–32), and phosphate 1.8 mmol/L (reference 0.8–1.5).

He has a functioning left radiocephalic arteriovenous fistula created 4 months ago.

Which of the following is the most appropriate approach?

A 56-year-old woman on chronic haemodialysis via a right internal jugular tunnelled catheter for 14 months presents with progressive right arm and facial swelling over the past 2 weeks. She also reports distended veins on her right chest wall. Her dialysis catheter is functioning but with reduced blood flow rates.

Which of the following is the most likely diagnosis?

A 60-year-old man with ESKD secondary to membranous nephropathy has been on automated peritoneal dialysis (APD) for 12 months.

He has type 2 diabetes mellitus and his HbA1c has risen from 7.2% (55 mmol/mol) to 9.5% (80 mmol/mol) over the past 6 months despite no change in his oral hypoglycaemic medications or diet.

His current PD prescription uses 2.5% glucose dialysate for all exchanges.

Which of the following is the most likely explanation for his worsening glycaemic control?

A 48-year-old woman on thrice-weekly in-centre haemodialysis for ESKD secondary to lupus nephritis has her dialysis adequacy assessed.

Her pre-dialysis blood urea is 28 mmol/L and her post-dialysis blood urea is 8 mmol/L.

Her delivered single-pool Kt/V is calculated as 1.0.

Which of the following best reflects the adequacy of her dialysis prescription?

A 65-year-old man who has been on haemodialysis via a left brachiocephalic arteriovenous fistula for 3 years presents with progressive swelling of his left hand and forearm. The fistula has a strong thrill and bruit. His left hand is warm with intact capillary refill, and there is no evidence of infection.

Duplex ultrasound shows a patent fistula with high flow (2,500 mL/min) and reversal of flow in the distal brachial artery.

Which of the following is the most likely cause of his symptoms?

A 59-year-old Indigenous Australian man has been on in-centre haemodialysis for 4 years for ESKD secondary to diabetic nephropathy. He asks about his long-term prognosis.

Which of the following is the leading cause of death among dialysis patients in Australia?

A 52-year-old woman with ESKD secondary to chronic glomerulonephritis is discussing modality options with her nephrologist. She has a residual urine output of approximately 1 litre per day. She is informed that one modality may better preserve her residual kidney function.

Which of the following statements regarding residual renal function and dialysis modality is most accurate?

A 60-year-old man with ESKD is medically suitable for all forms of renal replacement therapy. He lives in a remote area of regional Australia.

His renal team is discussing with him the health system costs and logistical considerations of different dialysis modalities.

Based on current Australian health economic data, which of the following correctly ranks the annual cost of dialysis modalities from most to least expensive?

A 70-year-old woman on thrice-weekly in-centre haemodialysis for ESKD secondary to hypertensive nephrosclerosis experiences recurrent episodes of intradialytic hypotension.

Her pre-dialysis weight is typically 3–4 kg above her prescribed dry weight.

Her dialysis sessions are 4 hours in duration with an ultrafiltration rate of 12 mL/kg/hour.

She takes amlodipine 10 mg daily, perindopril 5 mg daily, and prazosin 2 mg twice daily.

Her pre-dialysis blood pressure today is 160/90 mmHg, and midway through dialysis, she becomes symptomatic with a blood pressure of 80/50 mmHg.

Which of the following is the most appropriate initial strategy to reduce the frequency of her intradialytic hypotension?

A 63-year-old man with ESKD secondary to ANCA-associated vasculitis has been on thrice-weekly in-centre haemodialysis for 2 years via a left brachiocephalic arteriovenous fistula.

He is admitted to hospital with a large spontaneous haemarthrosis of the right knee.

His haemoglobin is 78 g/L (reference 130–175 g/L) and platelet count is 185 × 10⁹/L (reference 150–400 × 10⁹/L). His INR is 1.0 and aPTT is 32 seconds (reference 25–37 seconds). He requires ongoing haemodialysis during his admission.

Which of the following is the most appropriate anticoagulation strategy for his next haemodialysis session?

A 48-year-old woman has been on continuous ambulatory peritoneal dialysis (CAPD) for 8 years for ESKD secondary to reflux nephropathy.

Over the past 3 months, she has developed recurrent episodes of small bowel obstruction with nausea, vomiting, abdominal distension, and progressive ultrafiltration failure.

A CT abdomen reveals diffuse peritoneal thickening with calcification and tethering of bowel loops forming a cocoon-like mass.

Her peritoneal equilibration test shows a markedly elevated D/P creatinine ratio compared to her baseline performed 2 years ago.

Which of the following is the most likely diagnosis?

A 35-year-old man is brought to the emergency department 4 hours after intentionally ingesting an unknown quantity of methanol.

He is confused with a Glasgow Coma Scale of 11.

Investigations reveal:

• sodium 140 mmol/L (reference 135–145)
• potassium 4.5 mmol/L (reference 3.5–5.0)
• chloride 100 mmol/L (reference 95–110)
• bicarbonate 8 mmol/L (reference 22–32)
• urea 6.0 mmol/L (reference 3.0–8.0)
• creatinine 95 µmol/L (reference 60–110)
• glucose 5.5 mmol/L (reference 3.0–7.8 fasting)
• serum osmolality 340 mOsm/kg (reference 275–295)
• calculated osmolality is 295 mOsm/kg.
• An arterial blood gas confirms a pH of 7.10.

In addition to fomepizole, which of the following is the most appropriate renal intervention?

A 58-year-old woman is in the intensive care unit with septic shock secondary to urosepsis.

She has developed oliguric acute kidney injury with the following results:

• urea 38 mmol/L (reference 3.0–8.0)
• creatinine 520 µmol/L (reference 45–90)
• potassium 6.5 mmol/L (reference 3.5–5.0)
• bicarbonate 12 mmol/L (reference 22–32)

She is on noradrenaline at 25 µg/min and vasopressin at 2.4 units/hour to maintain a mean arterial pressure of 65 mmHg.

The intensive care team requests renal replacement therapy.

Which of the following is the most appropriate dialysis modality for this patient?

An 84-year-old woman with ESKD secondary to ischaemic nephropathy is referred to nephrology. Her eGFR is 8 mL/min/1.73m².

She has multiple comorbidities including severe ischaemic cardiomyopathy (ejection fraction 20%), advanced chronic obstructive pulmonary disease requiring home oxygen, peripheral vascular disease with bilateral below-knee amputations, and moderate cognitive impairment with a Mini-Mental State Examination score of 18/30.

She lives in a residential aged care facility. Her family asks whether dialysis would prolong her life.

Based on current evidence regarding dialysis versus conservative management in elderly patients with significant comorbidity, which of the following statements is most accurate?

A 52-year-old man is referred for evaluation of difficult-to-control blood pressure. He is adherent to amlodipine 10 mg daily, perindopril 10 mg daily, and indapamide 2.5 mg daily.

His office blood pressure is 158/96 mmHg on three separate occasions.

A 24-hour ambulatory blood pressure monitor confirms a mean daytime blood pressure of 152/94 mmHg and a mean nighttime blood pressure of 148/90 mmHg.

Investigations reveal:

• Sodium 141 mmol/L (135–145)
• Potassium 3.3 mmol/L (3.5–5.0)
• Creatinine 88 μmol/L (60–110)
• eGFR 82 mL/min/1.73m²
• Plasma aldosterone 620 pmol/L (100–950)
• Plasma renin activity 0.2 μg/L/hr (0.5–3.5)

Which of the following is the most appropriate next investigation?

A 48-year-old woman is referred to a hypertension clinic after three consecutive office visits showing blood pressures of 148/92 mmHg, 146/90 mmHg, and 150/94 mmHg.

She has no other cardiovascular risk factors and no evidence of hypertension-mediated organ damage. She takes no regular medications.

Her ECG is normal, urinalysis shows no proteinuria, and her creatinine is 68 μmol/L (45–90).

A 24-hour ambulatory blood pressure monitor is performed:

• Mean daytime blood pressure: 128/78 mmHg
• Mean nighttime blood pressure: 112/68 mmHg
• Mean 24-hour blood pressure: 122/74 mmHg

Which of the following is the most appropriate management?

A 67-year-old man with type 2 diabetes and chronic kidney disease attends for review. His medications include irbesartan 300 mg daily, amlodipine 10 mg daily, and atorvastatin 40 mg daily. He is clinically well with no symptoms of uraemia.

Investigations reveal:

• Creatinine 280 μmol/L (60–110)
• eGFR 18 mL/min/1.73m²
• Potassium 5.1 mmol/L (3.5–5.0)
• Urine albumin-to-creatinine ratio 85 mg/mmol (<2.5 in males)
• Blood pressure 134/78 mmHg

His general practitioner is concerned about the low eGFR and asks whether irbesartan should be ceased.

Which of the following is the most appropriate advice regarding irbesartan?

A 58-year-old woman with obesity (BMI 36 kg/m²), type 2 diabetes, and stage 2 chronic kidney disease (eGFR 72 mL/min/1.73m²) has confirmed true resistant hypertension on ambulatory blood pressure monitoring (mean daytime 154/92 mmHg).

She is adherent to ramipril 10 mg daily, amlodipine 10 mg daily, and indapamide 2.5 mg daily. Medication adherence has been confirmed by directly observed therapy. Secondary causes of hypertension have been excluded.

Investigations reveal:

• Sodium 140 mmol/L (135–145)
• Potassium 4.0 mmol/L (3.5–5.0)
• Creatinine 92 μmol/L (45–90)
• Aldosterone-to-renin ratio: normal

Which of the following is the most appropriate next pharmacological step?

A 34-year-old woman presents to the emergency department with severe headache, diaphoresis, and palpitations. Her blood pressure is 220/130 mmHg with a heart rate of 118 beats per minute.

An ECG demonstrates sinus tachycardia with T-wave inversions in the lateral leads.

Troponin I is mildly elevated at 52 ng/L (<16). An echocardiogram reveals apical ballooning with a left ventricular ejection fraction of 38%.

Physical examination reveals a café-au-lait macule on the trunk. Abdominal examination is unremarkable.

Investigations reveal:

• Sodium 139 mmol/L (135–145)
• Potassium 4.2 mmol/L (3.5–5.0)
• Creatinine 74 μmol/L (45–90)
• Plasma free metanephrines: elevated at 5 times the upper limit of normal
• 24-hour urinary fractionated metanephrines: markedly elevated

Which of the following is the most appropriate initial pharmacological management of this patient’s hypertension?

A 54-year-old woman with biopsy-proven IgA nephropathy is reviewed in the nephrology clinic. She has been on ramipril 10 mg daily for the past two years. Her blood pressure is 126/74 mmHg.

Investigations reveal:

• Creatinine 156 μmol/L (45–90)
• eGFR 34 mL/min/1.73m²
• Potassium 4.6 mmol/L (3.5–5.0)
• HbA1c 5.4% (4.0–6.0%)
• Urine albumin-to-creatinine ratio (ACR) 120 mg/mmol (<2.5 in females)

Two weeks after commencing dapagliflozin 10 mg daily, her repeat creatinine is 182 μmol/L with an eGFR of 28 mL/min/1.73m². She is clinically well and euvolaemic.

Which of the following is the most appropriate next step in management?

A 62-year-old man with type 2 diabetes, heart failure with reduced ejection fraction, and chronic kidney disease (eGFR 38 mL/min/1.73m²) is admitted to hospital for elective laparoscopic cholecystectomy.

His medications include empagliflozin 10 mg daily, metformin 500 mg twice daily, gliclazide MR 60 mg daily, ramipril 5 mg daily, carvedilol 12.5 mg twice daily, and frusemide 40 mg daily. His HbA1c is 7.2% (4.0–6.0%).

On the morning of postoperative day 1, he develops nausea, vomiting, and abdominal discomfort. His blood glucose level is 9.8 mmol/L (3.0–7.8 fasting). His heart rate is 104 bpm and blood pressure is 108/68 mmHg.

Investigations reveal:

• Venous pH 7.24 (7.35–7.45)
• Bicarbonate 14 mmol/L (22–32)
• Anion gap 22 mmol/L (8–16)
• Blood ketones 4.8 mmol/L (<0.6)
• Lactate 1.2 mmol/L (0.5–2.2)

Which of the following is the most important predisposing factor for this presentation?

A 71-year-old man with type 2 diabetes and chronic kidney disease secondary to diabetic nephropathy attends his nephrology review.

He is on losartan 100 mg daily, amlodipine 5 mg daily, and insulin glargine 24 units at night. His blood pressure is 132/76 mmHg and he is euvolaemic.

Investigations reveal:

• Creatinine 248 μmol/L (60–110)
• eGFR 22 mL/min/1.73m²
• Potassium 4.8 mmol/L (3.5–5.0)
• HbA1c 7.6% (4.0–6.0%)
• Urine ACR 180 mg/mmol (<3.5 in males)

His nephrologist is considering adding dapagliflozin.

Which of the following statements most accurately reflects the expected benefit of SGLT2 inhibitors in this patient?

A 66-year-old woman with type 2 diabetes, chronic kidney disease (eGFR 32 mL/min/1.73m²), and resistant hypertension is being managed with perindopril 10 mg daily, amlodipine 10 mg daily, indapamide 2.5 mg daily, and spironolactone 25 mg daily.

Her blood pressure is 142/88 mmHg on ambulatory monitoring.

Her potassium is 5.3 mmol/L (3.5–5.0) and urine ACR is 95 mg/mmol (<3.5 in females).

You wish to add an SGLT2 inhibitor for cardiorenal protection.

Which of the following best describes the effect of SGLT2 inhibitors on serum potassium in this clinical setting?

A 49-year-old woman with biopsy-proven focal segmental glomerulosclerosis (FSGS), no diabetes, and an eGFR of 42 mL/min/1.73m² is on maximum dose ramipril.

Her urine ACR is 280 mg/mmol (<2.5 in females) and HbA1c is 5.2% (4.0–6.0%).

You recommend commencing dapagliflozin 10 mg daily. She questions whether this medication is appropriate given that she does not have diabetes.

Which of the following trial findings best supports the use of dapagliflozin in this patient?