What is the workup for Chronic Kidney Disease (CKD)?

Comprehensive Workup for Chronic Kidney Disease (CKD)

The workup for Chronic Kidney Disease (CKD) should include both urine albumin measurement and assessment of glomerular filtration rate (GFR), with confirmation of abnormal results to establish chronicity of at least 3 months. 1

Initial Diagnostic Testing

• Test for both estimated GFR (eGFR) and albuminuria using urinary albumin-to-creatinine ratio (ACR) as these are the primary markers for CKD diagnosis 1
• Use serum creatinine with an estimating equation (eGFRcr) for initial assessment of GFR 1
• If cystatin C is available, use the combination of creatinine and cystatin C (eGFRcr-cys) for more accurate GFR estimation, especially when clinical decisions are significantly impacted 1
• Following detection of elevated ACR, hematuria, or low eGFR, repeat tests to confirm the presence of CKD 1

Establishing Chronicity

Proof of chronicity (minimum 3 months) can be established by:

• Review of past GFR measurements/estimations 1
• Review of past albuminuria/proteinuria measurements and urine microscopic examinations 1
• Imaging findings showing reduced kidney size or cortical thickness 1
• Kidney pathological findings such as fibrosis and atrophy 1
• Medical history, especially conditions known to cause CKD 1
• Repeat measurements within and beyond the 3-month point 1

Determining Cause of CKD

• Establish the cause using clinical context, personal and family history, social and environmental factors, medications, physical examination, laboratory measures, imaging, and genetic and pathologic diagnosis 1
• Consider kidney biopsy when clinically appropriate to evaluate cause and guide treatment decisions 1
• Use appropriate tests based on available resources to establish the cause 1

Risk Assessment

• In people with CKD G3-G5, use externally validated risk equations to estimate the absolute risk of kidney failure 1
• Consider nephrology referral when 5-year kidney failure risk is 3-5% 1, 2
• Use a 2-year kidney failure risk >10% to determine timing for multidisciplinary care 1
• For cardiovascular risk prediction, use validated models that incorporate eGFR and albuminuria 1

Laboratory Evaluation

• Complete blood count to assess for anemia 1
• Comprehensive metabolic panel including electrolytes, calcium, phosphorus 1
• Serum albumin and total protein 1
• Lipid profile 3
• Parathyroid hormone (PTH) levels in advanced CKD 1
• Vitamin D levels 1
• Urinalysis with microscopy for casts and epithelial cells 1
• Urine albumin-to-creatinine ratio as a sensitive and specific marker for CKD 1

Imaging Studies

• Renal ultrasound to assess kidney size, echogenicity, and structural abnormalities (e.g., hydronephrosis, cysts, scarring) 1
• Consider CT or MRI in specific situations, with careful consideration of contrast use 1
• For patients with CKD, iodinated contrast should be used cautiously due to risk of contrast-induced nephropathy 1
• If gadolinium-based contrast agents are needed for MRI, use Group II agents at the lowest diagnostic dose 1

Management Considerations During Workup

• Adjust medication dosages based on kidney function, particularly for antibiotics and oral hypoglycemic agents 3
• For ACE inhibitors, modify dosing based on creatinine clearance: normal to mild impairment (>30 mL/min): 10 mg/day; moderate to severe impairment (10-30 mL/min): 5 mg/day; dialysis patients (<10 mL/min): 2.5 mg/day 4
• Avoid nephrotoxic medications when possible, particularly NSAIDs 3
• Implement comprehensive treatment strategy to reduce risks of CKD progression and complications 1

Referral to Nephrology

• Refer all patients with CKD stages 4-5 (GFR <30 mL/min/1.73 m²) to nephrology 5
• Consider earlier referral for patients with:
  • Rapid decline in GFR 3
  • Albuminuria ≥300 mg per 24 hours 3
  • Difficult to manage complications (hyperkalemia, metabolic acidosis, secondary hyperparathyroidism) 3
  • Suspected glomerular disease or vasculitis 3

Monitoring and Follow-up

• Monitor for complications of CKD including hyperkalemia, metabolic acidosis, hyperphosphatemia, vitamin D deficiency, secondary hyperparathyroidism, and anemia 3
• Assess cardiovascular risk factors and implement appropriate interventions 3
• Encourage lifestyle modifications including physical activity, optimal body weight, and smoking cessation 1
• Advise plant-dominant, low-protein, and low-salt diet to help mitigate glomerular hyperfiltration 6

Pitfalls to Avoid

• Do not assume chronicity based on a single abnormal eGFR or ACR measurement, as it could result from acute kidney injury 1
• Do not rely solely on serum creatinine without calculating eGFR, as this can lead to missed diagnoses 1
• Consider the influence of muscle mass, diet, and medications on serum creatinine levels when interpreting results 1
• Recognize that early CKD is often asymptomatic, making screening of high-risk populations crucial 7