What is the initial workup for an adult with Chronic Kidney Disease (CKD)?

Initial Workup for an Adult with Chronic Kidney Disease (CKD)

The initial workup for an adult with CKD should include measurement of both estimated glomerular filtration rate (eGFR) and urine albumin-to-creatinine ratio (UACR), as these are essential for diagnosis, staging, and risk stratification. 1

Diagnostic Confirmation

1. Confirm CKD diagnosis:

   • Verify chronicity (abnormalities present for >3 months) through:
     • Review of past eGFR measurements
     • Review of past albuminuria/proteinuria measurements
     • Imaging findings (reduced kidney size, cortical thinning)
     • Medical history review 1
   • Do not assume chronicity based on a single abnormal result 1

2. Essential laboratory tests:

   • Serum creatinine with eGFR calculation
   • Urine albumin-to-creatinine ratio (UACR)
   • Complete blood count (CBC) with differential
   • Comprehensive metabolic panel
   • Urinalysis with microscopic examination 2

Risk Stratification

1. CKD staging and risk classification:

   • Classify according to KDIGO CKD prognosis system using:
     • eGFR categories (G1-G5)
     • Albuminuria categories (A1-A3) 1
   • Risk stratification into low, moderate, high, or very high risk based on the combination of eGFR and albuminuria 1

2. Cardiovascular risk assessment:

   • Estimate 10-year cardiovascular risk using validated risk tools 1
   • Screen for other modifiable cardiovascular risk factors 1

Evaluation of Etiology

1. Determine potential causes:

   • Review medical history for diabetes, hypertension, cardiovascular disease
   • Family history of kidney disease
   • Medication review (NSAIDs, nephrotoxic drugs)
   • Social and environmental exposures 1

2. Additional testing based on clinical suspicion:

   • Renal ultrasonography to assess kidney size, structure, and rule out obstruction 2
   • Consider specialized laboratory tests if indicated:
     • Serum and urine protein electrophoresis
     • Complement levels
     • Autoimmune markers
     • Hepatitis B, C, and HIV serology 2

3. Consider kidney biopsy:

   • When cause remains unclear after initial workup
   • Rapid decline in kidney function
   • Significant proteinuria
   • Active urinary sediment 1

Management Planning

1. Blood pressure management:

   • Target BP <130/80 mmHg for adults with CKD 1
   • Consider ACE inhibitor or ARB, especially with albuminuria ≥300 mg/g 1

2. Medication review and adjustment:

   • Evaluate current medications for potential nephrotoxicity
   • Adjust medication dosages as needed based on eGFR
   • Consider SGLT2 inhibitors for appropriate patients 1

3. Metabolic complications screening:

   • Electrolytes (potassium, sodium)
   • Acid-base status
   • Calcium and phosphate
   • Vitamin D levels
   • Parathyroid hormone 3

Common Pitfalls to Avoid

1. Relying solely on serum creatinine:

   • Can be misleading in patients with low muscle mass or malnutrition
   • Use eGFR equations that incorporate age, sex, race, and body size 2, 4

2. Neglecting albuminuria assessment:

   • Essential for CKD diagnosis and risk stratification
   • Use UACR rather than urine dipstick for detection 1, 2

3. Assuming all renal dysfunction is CKD:

   • Rule out acute kidney injury
   • Consider non-renal causes of elevated BUN 2

4. Delaying nephrology referral:

   • Refer promptly if:
     • eGFR <30 mL/min/1.73 m²
     • Albuminuria ≥300 mg/g
     • Rapid decline in eGFR
     • Unclear etiology requiring biopsy 3

By following this systematic approach to the initial workup of CKD, clinicians can accurately diagnose, stage, and develop appropriate management plans to reduce morbidity and mortality associated with kidney disease progression and its complications.