My estimated glomerular filtration rate is 18 mL/min/1.73 m²; what stage of chronic kidney disease does this represent and what immediate management is recommended?

eGFR 18 mL/min/1.73 m²: Stage G4 CKD Requiring Urgent Nephrology Referral

An eGFR of 18 mL/min/1.73 m² represents Stage G4 (severely decreased kidney function) chronic kidney disease, and you must refer this patient to nephrology immediately, as guidelines mandate referral when eGFR falls below 30 mL/min/1.73 m². 1, 2

CKD Stage Classification

• Stage G4 CKD is defined as eGFR 15-29 mL/min/1.73 m², placing your patient with eGFR 18 in this severely decreased kidney function category 2
• This stage carries high risk for progression to kidney failure requiring dialysis or transplantation 3
• Patients at this stage face markedly elevated cardiovascular mortality risk and require intensive monitoring 3

Immediate Nephrology Referral

You must refer to nephrology now—this is not optional. 1, 2

• Guidelines explicitly state referral is required when eGFR <30 mL/min/1.73 m² 1, 2
• Refer promptly for any uncertainty about CKD etiology, difficult management issues (refractory hypertension, persistent hyperkalemia), or rapidly progressing kidney disease 1
• The nephrologist will evaluate for kidney replacement therapy planning (dialysis vs. transplantation) 2

Urgent Laboratory Assessment

Measure the following immediately to assess CKD complications that emerge below eGFR 60: 2

• Serum potassium (hyperkalemia risk)
• Calcium and phosphorus (mineral bone disease)
• Parathyroid hormone (secondary hyperparathyroidism)
• Hemoglobin (anemia of CKD)
• Bicarbonate (metabolic acidosis screening)
• Urinary albumin-to-creatinine ratio (if not recently checked) 1

Monitoring Frequency

• Check eGFR and urinary albumin twice annually at minimum to guide therapy 1, 2
• More frequent monitoring if clinically unstable or if values are declining rapidly 1

Kidney-Protective Pharmacotherapy

For Patients WITH Diabetes:

SGLT2 inhibitors remain indicated at this eGFR level: 1

• Use SGLT2 inhibitor if eGFR ≥20 mL/min/1.73 m² (your patient at 18 is just below this threshold, but some agents may still be considered) 1
• However, at eGFR 18, most SGLT2 inhibitors should NOT be initiated per current labeling, though continuation may be considered if already established 1

Nonsteroidal mineralocorticoid receptor antagonist (finerenone): 1, 2

• Recommended if eGFR ≥25 mL/min/1.73 m² for cardiovascular and CKD progression risk reduction 1
• Your patient at eGFR 18 falls below this threshold

GLP-1 receptor agonist: 1

• Consider for cardiovascular risk reduction 1
• No specific eGFR cutoff for most agents

ACE inhibitor or ARB: 1, 2

• Continue if already on therapy, especially if urinary albumin ≥300 mg/g 1, 2
• Use maximally tolerated doses 2
• Do not discontinue for creatinine increases ≤30% in absence of volume depletion 1

For Patients WITHOUT Diabetes:

• ACE inhibitor or ARB if albuminuria present 2
• Statin therapy for cardiovascular risk reduction 2

Blood Pressure Management

• Target systolic BP <120 mmHg to reduce CKD progression 2
• Optimize BP control and reduce BP variability 1, 2
• Intensive BP lowering is safe even with up to 30% creatinine increase 2

Dietary and Lifestyle Modifications

Protein restriction is mandatory at this stage: 1, 2

• Limit dietary protein to 0.8 g/kg/day maximum for non-dialysis Stage G3 or higher CKD 1, 2
• This slows CKD progression 2

Additional interventions: 2

• Smoking cessation (if applicable)
• Moderate-intensity physical activity for at least 150 minutes weekly 1
• Sodium restriction to <2 g/day (<5 g sodium chloride) 1

Medication Safety Review

• Review ALL medications for appropriate dosing at eGFR <30 mL/min/1.73 m² 2
• Avoid nephrotoxins: NSAIDs, iodinated contrast (use only when essential with appropriate prophylaxis) 2
• Discontinue metformin if eGFR <30 mL/min/1.73 m² 1

Metabolic Complications Management

• Treat metabolic acidosis if bicarbonate low 2
• Manage hyperkalemia (common at this stage)
• Treat anemia per guidelines (likely erythropoiesis-stimulating agents needed)
• Manage mineral bone disease with phosphate binders and vitamin D analogs as indicated 2

Albuminuria Monitoring (If Present)

• If urinary albumin ≥300 mg/g, target ≥30% reduction from baseline with therapy, as this correlates with improved renal and cardiovascular outcomes 1, 2

Common Pitfalls to Avoid

• Do not delay nephrology referral—at eGFR 18, the patient needs pre-dialysis education and access planning 2
• Do not stop ACE inhibitor/ARB for minor creatinine increases (<30%) without evidence of volume depletion 1
• Do not use eGFR equations in acute kidney injury—they are validated only for stable CKD 4, 5
• Most SGLT2 inhibitors should not be initiated at eGFR <20-25 depending on the agent 1