CKD Monitoring Labs
Monitor eGFR and albuminuria (UACR) at least annually in all patients with CKD, with more frequent testing every 3-5 months for stage 4 CKD (eGFR 15-29 mL/min/1.73 m²) and every 1-3 months for stage 5 CKD (eGFR <15 mL/min/1.73 m²). 1, 2
Core Monitoring Parameters
eGFR and Albuminuria
- eGFR should be calculated using a prediction equation (such as CKD-EPI) rather than relying on serum creatinine alone, as creatinine doesn't rise above normal until GFR declines to approximately half of normal 1, 3
- Albuminuria assessment via spot urine albumin-to-creatinine ratio (UACR) is preferred over 24-hour urine collections for convenience and accuracy 1, 4
- Both parameters must be monitored together as they provide complementary information about kidney damage and function 1, 5
Monitoring Frequency by CKD Stage
- Stage 3 CKD (eGFR 30-59 mL/min/1.73 m²): Every 6-12 months 1, 2
- Stage 4 CKD (eGFR 15-29 mL/min/1.73 m²): Every 3-5 months 1, 2
- Stage 5 CKD (eGFR <15 mL/min/1.73 m²): Every 1-3 months 1, 2
Additional Laboratory Monitoring
Electrolytes and Metabolic Parameters
- Serum potassium must be monitored in all patients on ACE inhibitors, ARBs, or diuretics due to risk of hyperkalemia or hypokalemia 1, 2
- Serum electrolytes to assess for metabolic acidosis 1, 2
- Serum calcium and phosphate for metabolic bone disease screening 1, 2
- Parathyroid hormone (PTH) and vitamin 25(OH)D when eGFR falls below 60 mL/min/1.73 m² 1, 2
Anemia Screening
- Hemoglobin levels should be checked, with iron studies if indicated, as anemia becomes increasingly prevalent with advancing CKD 1, 2
High-Risk Populations Requiring More Frequent Monitoring
Increase monitoring frequency beyond the standard schedule for patients with: 1, 2
- Recent initiation or dose adjustment of hemodynamically active medications (ACE inhibitors, ARBs, SGLT2 inhibitors, diuretics) 1, 2
- Rapid eGFR decline or doubling of UACR on subsequent testing 1
- Diabetes with ACR ≥300 mg/g (monitor for 30% reduction in albuminuria as treatment target) 1
- African American ethnicity, diabetes, hypertension, hepatitis C coinfection, or HIV with CD4+ <200 cells/mL 1
Clinically Significant Changes Requiring Evaluation
eGFR Changes
- >20% decline in eGFR on subsequent testing exceeds expected variability and warrants investigation 1
- >30% decline in eGFR after initiating hemodynamically active therapies (ACE inhibitors, ARBs, SGLT2 inhibitors) exceeds expected variability and requires evaluation 1, 2
Albuminuria Changes
- Doubling of UACR on subsequent testing exceeds laboratory variability and warrants evaluation 1
Critical Pitfalls to Avoid
- Do not confuse small creatinine elevations (up to 30%) with ACE inhibitors or ARBs with acute kidney injury—these are expected hemodynamic changes, not true AKI 1, 2
- Do not use serum creatinine alone to assess kidney function, as it misses early CKD and is affected by age, muscle mass, and diet 1, 4
- Do not order 24-hour urine collections for proteinuria monitoring—spot UACR is more convenient and equally accurate 1, 4
- Verify appropriate medication dosing when eGFR <60 mL/min/1.73 m² and minimize nephrotoxin exposure (NSAIDs, iodinated contrast) 1, 3
- Monitor blood pressure and volume status at every clinical encounter, not just during scheduled lab draws 1, 2
Special Considerations for Diabetes
- Annual screening with both eGFR and UACR is mandatory for all patients with diabetes, regardless of CKD stage 1
- Consider adding SGLT2 inhibitors or nonsteroidal mineralocorticoid receptor antagonists if residual albuminuria persists despite RAS inhibitor therapy 1
- Initial eGFR declines of ≤30% with SGLT2 inhibitors are expected and should not prompt discontinuation 1, 2