Monitoring eGFR in Severe Kidney Impairment (eGFR 25)
For a patient with severe kidney impairment (eGFR 25 mL/min/1.73 m²), laboratory evaluation including eGFR should be performed every 3-5 months. 1
Monitoring Schedule Based on CKD Stage
- For patients with eGFR 25 mL/min/1.73 m² (CKD stage 4), laboratory evaluations including eGFR should be performed every 3-5 months 1
- More frequent monitoring (every 1-3 months) is recommended if there are changes in medications that affect kidney function, signs of disease progression, or if the patient is approaching CKD stage 5 (eGFR <15 mL/min/1.73 m²) 1
- Monitoring frequency should increase if the patient has recently started medications that affect kidney function, such as ACE inhibitors, ARBs, SGLT2 inhibitors, or diuretics 1
Factors That May Require More Frequent Monitoring
- Recent initiation or dose adjustment of medications that affect kidney function (ACE inhibitors, ARBs, SGLT2 inhibitors) 1
- Signs of volume overload or depletion 1
- Electrolyte abnormalities, particularly hyperkalemia 1
- Acute illness or exposure to nephrotoxins 1
- High variability in previous eGFR measurements (patients with heart failure tend to have higher eGFR variability) 2
Additional Monitoring Recommendations
- Along with eGFR, monitor serum electrolytes, particularly potassium and calcium 1
- Assess for metabolic acidosis with serum electrolytes 1
- Check hemoglobin for anemia, which commonly occurs with CKD stage 4 1
- Evaluate for metabolic bone disease with serum calcium, phosphate, PTH, and vitamin 25(OH)D 1
- Monitor albuminuria to assess disease progression and response to therapy 1
Special Considerations
- If the patient is on medications requiring dose adjustments based on kidney function (such as metformin or certain aldosterone antagonists), more frequent monitoring may be needed 1
- For patients with diabetes and CKD, monitoring should include both eGFR and albuminuria at least annually, with more frequent monitoring for those at higher risk of progression 1
- If the patient has recently started SGLT2 inhibitors, be aware that there may be an initial, reversible decrease in eGFR that is generally not an indication to discontinue therapy 1
Common Pitfalls to Avoid
- Don't confuse small elevations in serum creatinine (up to 30%) with ACE inhibitors or ARBs with acute kidney injury 1
- Avoid relying solely on serum creatinine for monitoring kidney function in patients with extreme body compositions or significant muscle wasting 3
- Don't assume that eGFR variability is always pathological - some degree of variability (CV of 14%) is normal in CKD patients 2
- Remember that certain medications may need to be held during acute illness to prevent further kidney injury 1
By following these monitoring guidelines, you can appropriately track kidney function, adjust medications as needed, and detect complications early in the setting of severe kidney impairment.