At what creatinine level or creatinine to amine ratio does a patient warrant referral to nephrology?

Nephrology Referral Criteria Based on Creatinine and Albuminuria

Refer patients to nephrology when eGFR is <30 mL/min/1.73m², regardless of the albumin-to-creatinine ratio, as this represents severe kidney disease requiring specialized management and potential preparation for renal replacement therapy. 1, 2

Primary Referral Thresholds

eGFR-Based Referral (Most Important)

• Mandatory referral at eGFR <30 mL/min/1.73m² (Stage G4): This threshold applies across all albuminuria categories and represents the point where patients require nephrology evaluation for renal replacement therapy planning 1, 3
• Consider referral at eGFR 30-44 mL/min/1.73m² (Stage G3b): Particularly when combined with moderate-to-severe albuminuria (≥30 mg/g), as this combination significantly increases risk of progression 1
• Referral at eGFR 45-59 mL/min/1.73m² (Stage G3a): When accompanied by severely increased albuminuria (≥300 mg/g), indicating high-risk disease 1

Albumin-to-Creatinine Ratio (UACR) Considerations

• Normal UACR: <30 mg/g creatinine 1
• Moderately increased (microalbuminuria): 30-299 mg/g creatinine 1
• Severely increased (macroalbuminuria): ≥300 mg/g creatinine 1

The combination of eGFR and UACR determines urgency: patients with both low eGFR and high albuminuria require more immediate referral 1

Additional Urgent Referral Indications

Acute Changes Requiring Immediate Nephrology Consultation

• Acute kidney injury (AKI): Creatinine rise ≥0.3 mg/dL within 48 hours OR ≥50% increase from baseline within 7 days, especially if no clear reversible cause identified 1, 3
• Rapid progression: Abrupt sustained fall in eGFR or progressive decline over serial measurements without obvious explanation 2, 3
• Persistent proteinuria >1 g/day: Indicates significant kidney damage requiring specialized evaluation 3

Clinical Scenarios Warranting Referral

• Uncertain etiology: When the cause of renal dysfunction is unclear, nephrology consultation helps determine underlying pathology 2, 3
• Refractory hypertension: Requiring ≥4 antihypertensive agents, suggesting possible renovascular or parenchymal kidney disease 3
• Persistent electrolyte abnormalities: Particularly hyperkalemia, metabolic acidosis, or hypocalcemia that are difficult to manage 3
• Unexpectedly low eGFR in younger patients: Warrants investigation for hereditary or rapidly progressive kidney disease 3

Monitoring Frequency Before Referral

The frequency of monitoring depends on the stage of CKD 1:

• eGFR ≥60 with normal albuminuria: Annual monitoring if other CKD markers present
• eGFR 45-59 or moderate albuminuria: Monitor twice yearly
• eGFR 30-44 or severe albuminuria: Monitor three times yearly
• eGFR 15-29: Monitor four times yearly and ensure nephrology referral completed

Critical Management Points Before and During Referral

Immediate Actions When Creatinine Elevated

• Stop nephrotoxic medications: Discontinue NSAIDs, aminoglycosides, and vancomycin immediately 3
• Assess volume status: Correct dehydration and hypovolemia, which can cause prerenal azotemia 3
• Review all medications: Adjust dosages of renally-cleared drugs and hold ACE inhibitors/ARBs temporarily only if AKI with volume depletion present 2, 3

Important Caveats

• Small creatinine rises with ACE inhibitors/ARBs: Up to 30% increase from baseline is acceptable and does not indicate AKI in stable chronic kidney disease; these medications provide long-term renal protection 1
• Normal serum creatinine does not exclude CKD: In older adults, 80.6% of those with stage 3 CKD had creatinine ≤1.5 mg/dL, emphasizing the importance of calculating eGFR rather than relying on creatinine alone 4
• Confirm persistent albuminuria: Two of three UACR measurements collected within 3-6 months should be abnormal before diagnosing persistent albuminuria 1

Common Pitfalls to Avoid

• Do not delay referral waiting for "more significant" elevation—earlier nephrology involvement improves outcomes and allows adequate time (≥12 months) for dialysis preparation if needed 3, 5
• Do not assume stable creatinine of 2.0 mg/dL is benign—even mild renal insufficiency significantly increases cardiovascular risk and mortality 3, 6
• Do not reflexively discontinue ACE inhibitors/ARBs for minor stable elevations in chronic kidney disease, as these provide essential renoprotection 3
• Do not rely solely on serum creatinine in older adults—always calculate eGFR, as creatinine underestimates kidney disease in this population 4