What is the management approach for a patient with Chronic Kidney Disease (CKD) stage 3b, using the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) 2021 guidelines?

Management of CKD Stage 3b (eGFR 30-44 mL/min/1.73 m²)

For patients with CKD Stage 3b, you should refer to nephrology for ongoing specialist management, target blood pressure to <130/80 mmHg if albuminuria is present, initiate ACE inhibitor or ARB therapy (especially with significant albuminuria), add an SGLT2 inhibitor if diabetic or albuminuria ≥200 mg/g, and implement cardiovascular risk reduction strategies. 1

Nephrology Referral

• Refer all CKD Stage 3b patients to nephrology for ongoing management due to the moderate-severe decrease in GFR requiring specialist input. 1
• Urgent referral is indicated if persistent proteinuria >1 g/day (ACR ≥60 mg/mmol or PCR ≥100 mg/mmol), blood pressure refractory to ≥4 antihypertensive agents, or abrupt sustained eGFR decrease >20% after excluding reversible causes. 1

Blood Pressure Management

Target Blood Pressure

• Target BP <130/80 mmHg if albuminuria ≥30 mg/24 hours (or equivalent). 1, 2
• This lower target is based on SPRINT trial evidence showing cardiovascular and mortality benefits with intensive BP control in CKD patients, including those with Stage 3-4 disease. 3, 2
• For patients without albuminuria (<30 mg/24 hours), target BP <140/90 mmHg. 3

The evidence strongly supports these differentiated targets based on albuminuria status, as patients with proteinuria derive greater benefit from more intensive BP control for both cardiovascular protection and slowing CKD progression. 3

First-Line Antihypertensive Therapy

• Initiate ACE inhibitor or ARB as first-line therapy, titrating to maximally tolerated dose. 1, 2
• ACE inhibitors or ARBs are strongly recommended if albuminuria is severely increased (ACR ≥60 mg/mmol or PCR ≥100 mg/mmol), regardless of diabetes status. 1
• For moderate albuminuria (30-300 mg/24 hours), ACE inhibitor or ARB is suggested. 3

Critical Medication Considerations

• Never combine ACE inhibitor with ARB or direct renin inhibitor - this dual RAS blockade is contraindicated due to increased risks of hyperkalemia and acute kidney injury without additional benefits. 1, 2
• Do not discontinue ACE inhibitor/ARB for creatinine increases ≤30% in the absence of volume depletion, as modest increases reflect expected hemodynamic changes from reduced intraglomerular pressure. 3, 1, 2
• Investigate further GFR decline beyond 30% for volume contraction, nephrotoxic agents, or renovascular disease. 3

Hyperkalemia Management

• Manage elevated potassium with potassium-lowering measures rather than stopping the ACE inhibitor or ARB. 1
• Use potassium-wasting diuretics or potassium binders to allow continuation of nephroprotective RAS inhibitor therapy. 2
• Monitor serum creatinine and potassium levels periodically when using ACE inhibitors, ARBs, or diuretics. 3

SGLT2 Inhibitor Therapy

• Add an SGLT2 inhibitor if eGFR ≥20 mL/min/1.73 m² and the patient has type 2 diabetes or albuminuria ≥200 mg/g, as this provides additional renoprotective benefits beyond ACE inhibition. 1
• SGLT2 inhibitors reduce renal endpoints, primarily albuminuria progression, and cardiovascular events in CKD patients at increased cardiovascular risk. 3

This represents a major advance in CKD management, as SGLT2 inhibitors provide additive benefits to RAS blockade for both kidney and cardiovascular protection. 3

Lifestyle Modifications

• Restrict dietary sodium to <2 g/day (<90 mmol/day) to reduce fluid retention, enhance diuretic efficacy, and slow CKD progression. 4, 2
• Limit dietary protein intake to 0.8 g/kg/day in non-dialysis CKD patients. 3, 4
• Encourage regular exercise (30 minutes, 5 times per week), smoking cessation if applicable, and maintaining healthy body weight (BMI 20-25 kg/m²). 2

Cardiovascular Risk Reduction

• Prioritize cardiovascular risk reduction as CKD Stage 3b patients have markedly elevated cardiovascular risk. 1, 5
• Initiate statin therapy for cardiovascular protection. 5
• Given that most CKD patients die from cardiovascular complications rather than progressing to end-stage renal disease, cardiovascular risk management is paramount. 3, 6

Monitoring Strategy

• Monitor eGFR and proteinuria every 3-6 months. 2
• Check serum creatinine, potassium, and bicarbonate 2-4 weeks after any medication changes. 2
• Monitor for CKD complications including hyperkalemia, metabolic acidosis, hyperphosphatemia, vitamin D deficiency, secondary hyperparathyroidism, and anemia. 5
• Check for postural hypotension regularly when treating with BP-lowering drugs. 3

Nephrotoxin Avoidance

• Avoid nonsteroidal anti-inflammatory drugs (NSAIDs) and other potential nephrotoxins. 5
• Adjust drug dosing appropriately for reduced GFR (many antibiotics and oral hypoglycemic agents require dose adjustment). 5

Common Pitfalls to Avoid

• Do not prematurely discontinue ACE inhibitors or ARBs when creatinine rises by less than 30%, as this reflects expected hemodynamic changes. 1, 2
• Do not immediately stop RAS inhibitors for hyperkalemia without first attempting medical management with potassium-lowering measures. 1
• Do not use dual RAS blockade (ACE inhibitor plus ARB, or either with direct renin inhibitor) as this increases harm without benefit. 1, 2
• Recognize that excessive diuresis can precipitate acute kidney injury, particularly in CKD patients with reduced renal reserve. 4