What is the recommended management for an adult with chronic kidney disease stage IIIb (estimated glomerular filtration rate 30‑44 mL/min/1.73 m²)?

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

For adults with CKD stage IIIb, initiate an SGLT2 inhibitor (if eGFR ≥20 mL/min/1.73 m²) and continue or start a RAS inhibitor (ACEi or ARB) at the maximum tolerated dose, while implementing comprehensive monitoring for CKD complications and cardiovascular risk reduction. 1

Core Pharmacologic Interventions

SGLT2 Inhibitors - First-Line Therapy

• Start an SGLT2 inhibitor immediately in all patients with CKD stage IIIb, regardless of diabetes status, as this represents the single most important intervention to slow progression 1
• For patients with diabetes and eGFR 30-44 mL/min/1.73 m²: SGLT2i is a 1A recommendation 1
• For patients without diabetes but with albuminuria ≥200 mg/g (≥20 mg/mmol): SGLT2i is a 1A recommendation 1
• For patients without diabetes and albuminuria <200 mg/g: SGLT2i is a 2B recommendation 1

Specific dosing for stage IIIb (eGFR 30-44 mL/min/1.73 m²):

• Canagliflozin: maximum 100 mg daily 1
• Dapagliflozin: 10 mg daily 1
• Empagliflozin: 10 mg daily 1
• Ertugliflozin: not recommended at this eGFR 1

Critical practice points:

• Once initiated, continue SGLT2i even if eGFR falls below 20 mL/min/1.73 m² until dialysis 1
• Withhold temporarily during prolonged fasting, surgery, or critical illness to reduce ketoacidosis risk 1
• The initial eGFR dip (typically 3-5 mL/min) is expected and not an indication to stop therapy 1

RAS Inhibition - Continue or Initiate

• Use ACEi or ARB at the highest approved tolerated dose because trial benefits were achieved at these doses 1, 2
• Continue RAS inhibitors even when eGFR falls below 30 mL/min/1.73 m² 1, 2
• Check BP, creatinine, and potassium within 2-4 weeks of initiation or dose increase 1, 2

When to reduce or stop:

• Serum creatinine rises >30% within 4 weeks of initiation 1, 2
• Symptomatic hypotension despite management 1, 2
• Uncontrolled hyperkalemia despite potassium-lowering interventions 1, 2
• eGFR <15 mL/min/1.73 m² with uremic symptoms 2

Hyperkalemia management (before stopping RAS inhibitor):

• Dietary potassium restriction 2
• Potassium binders (patiromer, sodium zirconium cyclosilicate) 2
• Loop diuretics if volume overloaded 2

Metformin - Dose Adjustment Required

• Reduce metformin dose to 1000 mg/day maximum at eGFR 30-44 mL/min/1.73 m² 1
• Monitor eGFR every 3-6 months at this stage 1
• Stop metformin if eGFR falls below 30 mL/min/1.73 m² 1
• Monitor vitamin B12 annually if on metformin >4 years 1

Additional Glucose-Lowering Agents (if diabetic and not at target)

• GLP-1 receptor agonists are second-line after SGLT2i and metformin 1
  • Dulaglutide, liraglutide, or semaglutide require no dose adjustment at stage IIIb 1
  • Prioritize agents with proven cardiovascular benefits (liraglutide, semaglutide, dulaglutide) 1
  • Start low and titrate slowly to minimize GI side effects 1

Mineralocorticoid Receptor Antagonists

• Consider nonsteroidal MRA (finerenone) if albuminuria persists >30 mg/g despite maximum RASi and SGLT2i 1
• Requires eGFR >25 mL/min/1.73 m² and normal potassium 1
• Most appropriate for high-risk patients with persistent albuminuria 1

Cardiovascular Risk Reduction

Blood Pressure Management

• Target BP <120/80 mmHg if tolerated, particularly if albuminuria present 1
• Use RAS inhibitors as first-line antihypertensive 1
• Add additional agents (calcium channel blockers, diuretics) as needed 3

Lipid Management

• Initiate statin therapy for cardiovascular risk reduction regardless of baseline LDL 3
• High-intensity statin preferred in most patients with CKD stage IIIb 3

Monitoring for CKD Complications

Laboratory Monitoring Schedule

• eGFR and creatinine: every 3-6 months at stage IIIb 1, 3
• Potassium: every 3-6 months, more frequently if on RASi or MRA 1
• Bicarbonate: screen for metabolic acidosis 3
• Phosphate and calcium: begin monitoring at stage IIIb 3
• PTH and vitamin D: assess for secondary hyperparathyroidism 3
• Hemoglobin: screen for anemia of CKD 3
• Urine albumin-to-creatinine ratio: at least annually 1

Specific Complications to Address

• Metabolic acidosis: treat if bicarbonate <22 mEq/L with oral alkali 3
• Hyperphosphatemia: dietary phosphate restriction, phosphate binders if needed 3
• Vitamin D deficiency: supplement as indicated 3
• Anemia: consider ESA or iron supplementation if hemoglobin <10 g/dL 3

Nephrotoxin Avoidance

Medications to Avoid or Adjust

• NSAIDs: avoid completely at stage IIIb due to AKI risk 3
• Aminoglycosides: use alternative antibiotics when possible 3
• Contrast agents: use lowest dose necessary, ensure adequate hydration 3
• Many antibiotics: require dose adjustment (fluoroquinolones, cephalosporins, etc.) 3
• Oral hypoglycemics: adjust doses per Table 4 guidelines 1

Referral to Nephrology

Refer promptly if any of the following:

• eGFR <30 mL/min/1.73 m² (approaching stage IV) 3
• Albuminuria ≥300 mg/24 hours 3
• Rapid eGFR decline (>5 mL/min/1.73 m² per year) 3
• Difficult-to-control hypertension or hyperkalemia 3
• Unexplained hematuria or unclear CKD etiology 3

Risk Stratification

Stage IIIb with normal/mild albuminuria (<3 mg/mmol): High risk category 1

Stage IIIb with moderate albuminuria (3-30 mg/mmol): Very high risk category 1

Stage IIIb with severe albuminuria (>30 mg/mmol): Very high risk category 1

This risk stratification determines intensity of monitoring and aggressiveness of intervention 1

Common Pitfalls to Avoid

• Do not stop RASi solely because eGFR is 30-44 mL/min/1.73 m² - continue unless specific contraindications develop 1, 2
• Do not withhold SGLT2i due to concerns about eGFR - benefits persist at low eGFR 1
• Do not automatically stop RASi for hyperkalemia - attempt medical management first 1, 2
• Do not use full-dose metformin - must reduce to ≤1000 mg/day at stage IIIb 1
• Do not delay nephrology referral - earlier diagnosis and intervention slow progression 4