What are the diagnostic and treatment approaches for a patient with Chronic Kidney Disease (CKD) stage 1?

CKD Stage 1: Diagnostic and Treatment Approach

For CKD Stage 1, test both eGFR and urine albumin, confirm chronicity with repeat testing over 3 months, identify the underlying cause, and initiate cardiovascular risk reduction with lifestyle modifications and treatment of comorbid conditions. 1

Diagnostic Criteria for CKD Stage 1

CKD Stage 1 is defined as kidney damage with normal or increased GFR (≥90 mL/min/1.73 m²) that persists for at least 3 months. 1, 2

Required Diagnostic Tests

• Measure both serum creatinine to calculate eGFR AND urine albumin-to-creatinine ratio (ACR) – both tests are mandatory for comprehensive CKD detection. 1, 2
• Use creatinine-based eGFR (eGFRcr) as the primary method; if cystatin C is available, combine it with creatinine (eGFRcr-cys) for more reliable GFR estimation. 1
• Albuminuria (ACR ≥30 mg/g) is the primary marker of kidney damage in Stage 1 CKD. 2

Confirming the Diagnosis

Do not diagnose CKD based on a single abnormal test – repeat testing is essential to confirm chronicity. 1

Establish chronicity through: 1

• Review of past GFR measurements or estimations
• Review of past albuminuria or proteinuria measurements
• Imaging findings (reduced kidney size, cortical thinning)
• Kidney biopsy findings (fibrosis, atrophy)
• Medical history of conditions causing CKD
• Repeat measurements within and beyond the 3-month timepoint

Critical pitfall: A single abnormal result could represent acute kidney injury (AKI) or acute kidney disease (AKD), not CKD. 1

Establishing the Cause

Determine the underlying cause using clinical context, personal and family history, medications, physical examination, laboratory measures, imaging, and when appropriate, kidney biopsy. 1, 2

Comprehensive Evaluation

• History: Focus on diabetes, hypertension, family history of kidney disease, medication history (especially NSAIDs and nephrotoxins), and systemic diseases. 2
• Basic laboratory tests: Complete blood count, comprehensive metabolic panel, urinalysis with microscopy, urine protein quantification. 2
• Additional testing based on clinical suspicion: Serologic testing for autoimmune diseases, complement levels, hepatitis B/C and HIV serology, serum and urine protein electrophoresis. 2
• Imaging: Renal ultrasound to assess kidney size, echogenicity, and rule out obstruction. 2
• Kidney biopsy: Consider when the cause is unclear and results would guide treatment decisions, particularly for rapidly progressive disease or suspected glomerular disease. 1, 2

Treatment Approach for CKD Stage 1

Primary Actions

The clinical action plan for Stage 1 focuses on three priorities: screening high-risk individuals, CKD risk reduction, and cardiovascular disease (CVD) risk reduction. 1, 3

Cardiovascular Risk Reduction

• Blood pressure control with target <130/80 mmHg. 3
• ACE inhibitors or ARBs are preferred for patients with albuminuria ≥30 mg/g, especially in diabetic kidney disease. 3
• Statin therapy for cardiovascular risk reduction. 4

Glycemic Control (if diabetic)

• Target HbA1c ≤7% for patients with diabetes, though individualization may be needed based on comorbidities. 3, 5
• For Type 1 diabetes, screen for CKD 5 years after diagnosis; for Type 2 diabetes, screen at diagnosis with annual monitoring using both eGFR and ACR. 2

Lifestyle Modifications

• Dietary modifications (sodium restriction, protein intake management). 1
• Smoking cessation. 4
• Weight management and physical activity. 1

Medication Safety

• Avoid nephrotoxins, particularly NSAIDs. 4, 5
• Review and adjust medication dosing based on kidney function. 5

Monitoring Strategy

• Monitor progression with serial eGFR and ACR measurements. 1, 3
• Patient and family education about CKD. 1
• Regular monitoring of kidney function, albuminuria, and complications to avoid inadequate surveillance. 3

When to Refer to Nephrology

Nephrology referral is not typically required for Stage 1 CKD unless there are specific concerns: 2

• Difficulty determining the cause of CKD
• Rapidly progressive disease
• Significant proteinuria requiring specialized management
• Complex management issues

Critical pitfall to avoid: Late nephrology referral – while Stage 1 doesn't routinely require nephrology involvement, ensure referral occurs no later than Stage 4 (eGFR <30 mL/min/1.73 m²). 3