What is the management for a patient with stage 3 chronic kidney disease, indicated by a BUN of 31, Cr of 1.56, and eGFRoglemerular Filtration Rate (eGFR) of 54?

Management of Stage 3 Chronic Kidney Disease

For a patient with Stage 3 CKD (eGFR 54 mL/min/1.73m²), you should immediately initiate blood pressure control targeting ≤140/90 mmHg (or ≤130/80 mmHg if albuminuria ≥30 mg/24h is present), screen for albuminuria to guide ACE inhibitor/ARB therapy, assess for CKD complications including anemia and mineral bone disease, and establish nephrology co-management given the moderate reduction in kidney function. 1

Immediate Diagnostic Steps

• Measure urine albumin-to-creatinine ratio (ACR) on a spot urine sample to classify albuminuria category (A1: <30 mg/g, A2: 30-299 mg/g, A3: ≥300 mg/g), as this determines both cardiovascular risk and treatment intensity 1

• Determine the underlying cause of CKD through history (diabetes duration, hypertension, family history, nephrotoxin exposure) and additional testing as indicated, since cause-specific treatments may be available 1

• Calculate precise eGFR using the CKD-EPI equation to determine if this represents Stage 3a (eGFR 45-59) or Stage 3b (eGFR 30-44), as Stage 3b requires more aggressive monitoring and earlier nephrology referral 2

Blood Pressure Management

• Target BP ≤140/90 mmHg if albuminuria is <30 mg/24h (A1 category) using any BP-lowering agent 1

• Target BP ≤130/80 mmHg if albuminuria is ≥30 mg/24h (A2 or A3 category), preferentially using ACE inhibitors or ARBs as first-line agents to reduce both BP and albuminuria progression 1, 2

• For diabetic nephropathy specifically (elevated creatinine with proteinuria/ACR ≥300 mg/g in type 2 diabetes), initiate losartan or another ARB as this reduces progression to doubling of serum creatinine or end-stage renal disease 3

Monitoring Frequency

• Monitor eGFR and ACR twice yearly (every 6 months) for Stage 3a CKD with A1 albuminuria 1

• Increase monitoring to 3-4 times yearly for Stage 3b CKD or if albuminuria is in the A2-A3 range, as these combinations represent higher risk for progression 1

• Define progression as both a change in eGFR category (e.g., G3a to G3b) AND a ≥25% decline in eGFR confirmed on repeat testing, to avoid misinterpreting normal fluctuations 1

Screening for CKD Complications

At eGFR <60 mL/min/1.73m², the prevalence of complications rises significantly, requiring systematic evaluation: 1

• Anemia screening: Check hemoglobin, as BUN elevation independent of eGFR is associated with anemia development in CKD 4

• Mineral bone disease: Assess calcium, phosphate, parathyroid hormone, and vitamin D levels 1

• Metabolic acidosis: Check serum bicarbonate 5

• Hyperkalemia risk: Baseline potassium, especially before initiating ACE inhibitors/ARBs 3

Nephrotoxin Avoidance and Drug Adjustments

• Avoid NSAIDs (including COX-2 inhibitors), as they can cause acute deterioration of renal function in CKD patients, particularly when combined with ACE inhibitors/ARBs 3

• Adjust medication dosing for renally-cleared drugs (many antibiotics, oral hypoglycemics, etc.) based on eGFR 1, 5

• Use the Cockcroft-Gault equation for drug dosing decisions rather than CKD-EPI, as most pharmacokinetic studies used this formula 1

Cardiovascular Risk Reduction

• Initiate statin therapy for cardiovascular risk reduction, as CKD patients are in the highest risk group for cardiovascular events, which are more common than progression to kidney failure 1, 5

• Implement comprehensive cardiovascular risk management including diabetes control (if present), smoking cessation, and limited sodium intake 1

Nephrology Referral Criteria

• Consider nephrology co-management now for Stage 3 CKD, as guidelines support specialist involvement to optimize management 1

• Mandatory nephrology referral if eGFR declines to <30 mL/min/1.73m² (Stage 4), albuminuria ≥300 mg/24h (A3), or rapid eGFR decline (>5 mL/min/1.73m² per year) 5

• Early referral prevents late referral complications, which are associated with increased mortality after dialysis initiation 1

Special Considerations for BUN Elevation

• The BUN of 31 mg/dL is elevated relative to the creatinine and may reflect high dietary protein intake, volume depletion, or gastrointestinal bleeding in addition to reduced GFR 6

• Higher BUN levels independently predict worse renal outcomes and anemia development beyond what eGFR alone predicts, suggesting BUN represents uremic toxin accumulation 6, 4

• Assess dietary protein intake and consider whether protein restriction is appropriate, though this should be balanced against nutritional status 6

Critical Medication Warnings

• Never combine two RAS inhibitors (ACE inhibitor + ARB, or either with aliskiren in diabetics), as the VA NEPHRON-D trial demonstrated increased hyperkalemia and acute kidney injury without additional benefit 3

• Monitor potassium closely when initiating ACE inhibitors/ARBs, especially with concomitant potassium-sparing diuretics, potassium supplements, or potassium-containing salt substitutes 3

• Avoid aliskiren entirely in patients with diabetes on losartan, and avoid in any patient with eGFR <60 mL/min/1.73m² 3