How should I manage a patient with an estimated glomerular filtration rate of 32.4 mL/min/1.73 m²?

Management of eGFR 32.4 mL/min/1.73 m²

A patient with an eGFR of 32.4 mL/min/1.73 m² has Stage G3b chronic kidney disease (moderately to severely decreased kidney function) and requires immediate nephrology referral, comprehensive screening for CKD complications, strict medication review with dose adjustments, and aggressive cardiovascular risk modification. 1

CKD Classification and Risk Profile

• An eGFR of 32.4 mL/min/1.73 m² places the patient in Stage G3b CKD (eGFR 30-44 mL/min/1.73 m²), representing loss of approximately two-thirds of normal kidney function. 1
• This stage carries substantially increased risks for cardiovascular disease, accelerated CKD progression, and mortality compared to earlier stages. 1
• The diagnosis requires confirmation with repeat eGFR measurement within 3 months to verify chronicity, as CKD is defined by persistent abnormalities for ≥3 months. 1

Mandatory Nephrology Referral

Immediate referral to nephrology is required because the patient meets multiple high-risk criteria:

• eGFR <45 mL/min/1.73 m² (the patient's 32.4 qualifies). 1
• Referral is particularly urgent if there is uncertainty about etiology, difficult management issues, rapidly progressing kidney disease, or confirmed proteinuria (UACR ≥300 mg/g). 2, 1
• For patients with diabetes and pre-existing CKD at this level, nephrology involvement is essential. 2

Comprehensive Screening for CKD Complications

At eGFR <60 mL/min/1.73 m² (and especially at 32.4), screen every 6-12 months for: 1

• Blood pressure monitoring (target <130/80 mmHg). 1
• Volume status assessment. 1
• Electrolyte abnormalities (particularly potassium). 1
• Metabolic acidosis. 1
• Anemia (hemoglobin monitoring). 1
• Mineral bone disease (measure serum calcium, phosphorus every 3-6 months; PTH every 6-12 months). 1

Critical Medication Management

All medications must be reviewed immediately as many require dose adjustment at eGFR <60 mL/min/1.73 m², with more significant modifications needed at this patient's level of 32.4 mL/min/1.73 m². 1, 3

Medications Requiring Strict Attention:

• NSAIDs must be strictly avoided as they reduce renal blood flow and can precipitate acute kidney injury. 1
• Metformin: At eGFR 30-44 mL/min/1.73 m², the dose should be halved; if eGFR drops below 30 mL/min/1.73 m², metformin must be stopped. 3
• Fenofibrate: Maximum dose 54 mg/day at eGFR 30-59 mL/min/1.73 m²; contraindicated if eGFR <30 mL/min/1.73 m². 3
• Contrast agents: When PCI or imaging with iodinated contrast is clinically needed, the risk of contrast-induced AKI should not be a reason to withhold it, but minimize risk through adequate hydration, minimization of contrast volume, and avoidance of nephrotoxic agents. 2

The 30 mL/min/1.73 m² threshold is particularly critical as it represents the boundary where many medications require substantial dose reduction or discontinuation. 3

Blood Pressure and Proteinuria Management

• Measure urine albumin-to-creatinine ratio (UACR) immediately if not already done, then annually. 1
• If albuminuria is present, use ACE inhibitor or ARB as first-line antihypertensive therapy. 1
• Target blood pressure <130/80 mmHg. 1
• Monitor serum creatinine and potassium 1-2 weeks after initiating or adjusting ACE inhibitor/ARB therapy. 1

Dietary Modifications

• Limit dietary protein to 0.8 g/kg body weight per day to reduce hyperfiltration injury and slow CKD progression at eGFR 30-44 mL/min/1.73 m². 1, 2
• Restrict sodium to <2 g/day to reduce blood pressure and maximize diuretic effectiveness if needed. 1

This protein restriction (0.8 g/kg/day) is critical at this stage and differs from less restrictive recommendations for milder CKD. 1

Glycemic Control (if diabetic)

• Target A1C of 7% to delay CKD progression. 1
• Intensive glucose control has been shown to delay onset and progression of albuminuria and reduce eGFR decline in both type 1 and type 2 diabetes. 1

Monitoring Frequency

• Measure eGFR and UACR at least annually. 1
• Laboratory monitoring for complications (electrolytes, acid-base status, anemia, mineral bone disease) every 6-12 months for Stage 3 CKD. 1

Vaccination

• Hepatitis B vaccination is indicated early in patients likely to progress to end-stage kidney disease. 1

Cardiovascular Risk Modification

• CKD at this stage markedly increases cardiovascular disease risk, requiring aggressive risk factor modification including lipid management, blood pressure control, and smoking cessation. 1
• In patients with chronic coronary disease and CKD, a team-based approach including cardiac and renal specialists is beneficial, especially when considering revascularization decisions. 2

Special Considerations for Revascularization (if applicable)

• In patients with moderate to severe ischemia and eGFR <30 mL/min/1.73 m² or on dialysis, revascularization added to guideline-directed medical therapy does not improve outcomes and should be reserved for patients who remain symptomatic despite medical therapy. 2
• High-dose statins may reduce the occurrence of contrast-induced AKI. 2

Critical Pitfalls to Avoid

• Do not rely on serum creatinine alone; always calculate and use eGFR for assessment of kidney function. 1
• Do not underestimate the severity of Stage 3b disease; despite being grouped under "stage 3," Stage 3b carries significantly higher risks than Stage 3a and warrants more aggressive monitoring. 1
• If creatinine-based eGFR appears discordant with the clinical picture, measure cystatin C-based eGFR for confirmation, as creatinine estimates are inaccurate in approximately 16-20% of individuals with eGFR <60 mL/min/1.73 m². 1