Chronic Kidney Disease (CKD) - MCCQE1 Preparation Guide

Introduction

Chronic Kidney Disease (CKD) is a significant health concern in Canada, affecting approximately 10% of the adult population. As a key topic for the MCCQE1 exam, understanding CKD is crucial for Canadian medical students. This comprehensive guide will cover essential aspects of CKD, focusing on Canadian guidelines and practices to help you prepare effectively for your MCCQE1 exam.

Epidemiology in Canada

• Prevalence: Approximately 4 million Canadians are living with CKD
• Risk factors:
  • Diabetes (leading cause in Canada)
  • Hypertension
  • Cardiovascular disease
  • Family history of kidney disease
  • Indigenous ancestry (3x higher risk)
  • Age >60 years

Etiology and Risk Factors

Pathophysiology

Understanding the pathophysiology of CKD is crucial for MCCQE1 success. Key concepts include:

1. Progressive loss of nephron function
2. Compensatory hyperfiltration of remaining nephrons
3. Glomerular sclerosis and tubulointerstitial fibrosis
4. Activation of the renin-angiotensin-aldosterone system (RAAS)

Clinical Presentation

CKD often presents insidiously. Key symptoms and signs to remember for the MCCQE1 exam include:

• Fatigue and weakness
• Edema
• Hypertension
• Nocturia
• Anorexia and nausea
• Pruritus (in advanced stages)
• Cognitive impairment

Diagnosis and Staging

Diagnosis of CKD is based on the following criteria:

1. Decreased GFR (<60 mL/min/1.73m²) for ≥3 months
2. Evidence of kidney damage for ≥3 months:
   • Albuminuria (AER ≥30 mg/24 hours; ACR ≥3 mg/mmol)
   • Urine sediment abnormalities
   • Electrolyte and other abnormalities due to tubular disorders
   • Abnormalities detected by histology
   • Structural abnormalities detected by imaging
   • History of kidney transplantation

CKD Staging

Management

Management of CKD in Canada focuses on:

1. Slowing disease progression
2. Managing complications
3. Preparing for renal replacement therapy (if necessary)

Canadian Guidelines for CKD Management

The Canadian Society of Nephrology provides specific guidelines for CKD management:

1. Use of ACE inhibitors or ARBs as first-line therapy for hypertension in CKD
2. Annual screening for albuminuria in high-risk populations
3. Referral to a nephrologist when eGFR <30 mL/min/1.73m²
4. Emphasis on patient education and shared decision-making

Complications

Common complications of CKD include:

• Anemia
• Mineral and bone disorders
• Cardiovascular disease
• Electrolyte imbalances
• Uremic encephalopathy
• Increased susceptibility to infections

Key Points to Remember for MCCQE1

1. CKD definition: kidney damage or GFR <60 mL/min/1.73m² for ≥3 months
2. Major risk factors in Canada: diabetes, hypertension, and Indigenous ancestry
3. Staging based on GFR and albuminuria
4. Importance of ACE inhibitors/ARBs in management
5. Canadian guidelines for referral to nephrology
6. Complications and their management
7. Emphasis on early detection and prevention in the Canadian healthcare system

Sample Question

A 55-year-old Indigenous woman presents for a routine check-up. She has a 10-year history of type 2 diabetes and hypertension. Her blood pressure is 142/88 mmHg, and recent lab results show: serum creatinine 130 μmol/L, eGFR 45 mL/min/1.73m², and urine ACR 5 mg/mmol. Which one of the following is the most appropriate next step in management?

• A. Refer to a nephrologist
• B. Start erythropoiesis-stimulating agent
• C. Initiate ACE inhibitor therapy
• D. Recommend renal replacement therapy education
• E. Increase frequency of HbA1c monitoring

Explanation

The correct answer is:

• C. Initiate ACE inhibitor therapy

This patient has stage 3a CKD (eGFR 45 mL/min/1.73m²) with albuminuria (ACR 5 mg/mmol). According to Canadian guidelines, ACE inhibitors or ARBs are first-line therapy for hypertension in CKD, especially with albuminuria. This treatment can slow CKD progression and reduce proteinuria.

Option A is incorrect as referral to a nephrologist is typically recommended when eGFR <30 mL/min/1.73m². Option B is not appropriate as there's no indication of anemia. Option D is premature at this stage of CKD. Option E, while important for diabetic management, is not the most crucial next step for CKD management.

This question tests your knowledge of CKD management in the Canadian context, particularly for high-risk groups like Indigenous patients with diabetes and hypertension.

References

1. Kidney Disease: Improving Global Outcomes (KDIGO) CKD Work Group. KDIGO 2012 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney Inter., Suppl. 2013; 3: 1–150.

2. Levin A, et al. Canadian Society of Nephrology commentary on the 2012 KDIGO clinical practice guideline for the evaluation and management of CKD. Am J Kidney Dis. 2015;65(2):177-205.

3. Arora P, et al. Prevalence estimates of chronic kidney disease in Canada: results of a nationally representative survey. CMAJ. 2013;185(9):E417-E423.

4. Grill AK, Brimble S. Approach to the detection and management of chronic kidney disease: What primary care providers need to know. Can Fam Physician. 2018;64(10):728-735.

5. Canadian Diabetes Association Clinical Practice Guidelines Expert Committee. Chronic Kidney Disease in Diabetes. Can J Diabetes. 2018;42 Suppl 1:S201-S209.