Pharmacologic and Monitoring Recommendations for CKD Stage IIIb (eGFR 30‑44 mL/min/1.73 m²)

Core Pharmacologic Interventions

SGLT2‑Inhibitors (First‑Line Therapy)

• Initiate an SGLT2 inhibitor in all adults with CKD stage IIIb (eGFR ≥ 20 mL/min/1.73 m²) as the single most important intervention to slow disease progression. 1
• For patients with diabetes and eGFR 30‑44 mL/min/1.73 m², the recommendation is Class 1, Level A. 2
• For patients without diabetes but with albuminuria ≥ 200 mg/g, the recommendation is Class 1, Level A. 1
• For patients without diabetes and albuminuria < 200 mg/g, the recommendation is Class 2, Level B. 1
• Dosing for stage IIIb:
  
  • Canagliflozin – maximum 100 mg once daily. 2
  • Dapagliflozin – 10 mg once daily. 2
  • Empagliflozin – 10 mg once daily. 2
  • Ertugliflozin – not recommended at this eGFR. 2
• Continue the SGLT2 inhibitor even if eGFR falls below 20 mL/min/1.73 m², maintaining therapy until dialysis is required. 1
• Withhold temporarily during prolonged fasting, surgery, or critical illness to reduce the risk of ketoacidosis. 1
• An initial eGFR dip of ~3‑5 mL/min is expected and should not prompt discontinuation. 1

Renin‑Angiotensin System (RAS) Inhibition

• Use an ACE inhibitor or ARB at the highest tolerated dose; trial benefits were achieved at these doses. 1
• Maintain RAS inhibition even when eGFR declines below 30 mL/min/1.73 m². 1
• Check blood pressure, serum creatinine, and potassium 2‑4 weeks after initiation or any dose increase. 1
• Reduce or stop the RAS inhibitor if any of the following occur:
  
  • Serum creatinine rises > 30 % within 4 weeks of initiation. 1
  • Symptomatic hypotension despite management. 1
  • Uncontrolled hyperkalemia despite potassium‑lowering measures. 1

Metformin

• Reduce metformin dose to a maximum of 1,000 mg per day when eGFR is 30‑44 mL/min/1.73 m². 2
• Monitor eGFR every 3‑6 months while on metformin at this stage. 3
• Discontinue metformin if eGFR falls below 30 mL/min/1.73 m². 3
• Perform annual vitamin B12 assessment in patients on metformin for >4 years. 3

Additional Glucose‑Lowering Agents (Diabetic Patients)

• GLP‑1 receptor agonists are recommended as second‑line therapy after SGLT2‑inhibitor and metformin. 3
• Dulaglutide, liraglutide, and semaglutide require no dose adjustment in CKD stage IIIb. 2
• Prioritize GLP‑1 agents with proven cardiovascular benefit (liraglutide, semaglutide, dulaglutide). 3
• Initiate at low dose and titrate slowly to minimize gastrointestinal adverse effects. 3

Non‑steroidal Mineralocorticoid Receptor Antagonist (MRA)

• Consider finerenone in patients with persistent albuminuria > 30 mg/g despite maximally tolerated RAS inhibition and SGLT2 inhibition. 1
• Eligibility requires eGFR > 25 mL/min/1.73 m² and normokalemia. 1

Cardiovascular Risk Reduction

Blood Pressure Management

• Target blood pressure < 120/80 mmHg if tolerated, especially in the presence of albuminuria. 1
• Use ACEi/ARB as the first‑line antihypertensive agent. 1

Monitoring for CKD Complications

Laboratory Monitoring Schedule

• eGFR and serum creatinine: every 3‑6 months in stage IIIb. 3
• Serum potassium: every 3‑6 months; increase frequency if the patient is on a RAS inhibitor or finerenone. 1
• Urine albumin‑to‑creatinine ratio: at least annually to assess albuminuria status. 1

Risk Stratification

• Normal/mild albuminuria (< 3 mg/mmol): classified as high risk. [4][5]
• Moderate albuminuria (3‑30 mg/mmol): classified as very high risk. [4][5]
• Severe albuminuria (> 30 mg/mmol): classified as very high risk. [4][5]
• The risk category guides the intensity of monitoring and the aggressiveness of therapeutic interventions. [4][5]

Common Pitfalls to Avoid

• Do not discontinue RAS inhibition solely because eGFR is 30‑44 mL/min/1.73 m²; continue unless a specific contraindication arises. 1
• Do not withhold SGLT2‑inhibitor therapy due to low eGFR; the renal and cardiovascular benefits persist at reduced kidney function. 1
• Do not automatically stop RAS inhibition for hyperkalemia; first employ dietary potassium restriction, potassium binders, or loop diuretics before cessation. 1
• Do not prescribe full‑dose metformin in stage IIIb; limit the dose to ≤ 1,000 mg/day. 2

Renal Dosing and Medication Management in CKD Stage 3b

Assessment of Renal Function for Drug Dosing

• Calculate absolute creatinine clearance (mL/min, not normalized to body surface area) when dosing antibiotics in patients who are markedly larger or smaller than average, because standard eGFR equations can cause under‑dosing or over‑dosing. 6

• Do not rely solely on serum creatinine; use validated eGFR equations (e.g., CKD‑EPI 2021) and also consider absolute clearance to guide dosing decisions. 6

• Adjust dosing calculations for body size, as normalized eGFR may lead to under‑dosing in larger patients and over‑dosing in smaller patients. 6

Therapeutic Drug Monitoring

• When serum drug concentrations are available (e.g., vancomycin, aminoglycosides), monitor levels and adjust doses based on both the measured renal function and the clinical response. 6

Medication Management During Acute Illness

• Temporarily discontinue metformin, ACE‑inhibitors/ARBs, and diuretics during a serious intercurrent illness that requires antibiotic therapy to lower the risk of acute kidney injury. 6

• Restart the above medications once the patient is clinically stable and the eGFR has returned to baseline values. 6