Renal · Year 2 · from Renal

Case 3: SGLT2 Inhibitor Initiation in CKD

Patient Presentation

Demographics: 58-year-old male

Chief Complaint: Follow-up for CKD management

History of Present Illness: The patient has CKD Stage 3b due to diabetic nephropathy with persistent albuminuria despite optimal ACE inhibitor therapy. He is referred to discuss additional renoprotective therapy. His diabetes is reasonably controlled on metformin and glipizide.

Past Medical History:

  • Type 2 diabetes mellitus (15 years, HbA1c 7.4%)
  • CKD Stage 3b (eGFR 38 mL/min/1.73m2)
  • Hypertension (controlled)

Current Medications:

  • Lisinopril 40 mg daily
  • Metformin 500 mg twice daily
  • Glipizide 10 mg twice daily
  • Amlodipine 5 mg daily
  • Atorvastatin 40 mg daily

Laboratory Studies:

  • Creatinine: 1.8 mg/dL
  • eGFR: 38 mL/min/1.73m2
  • Potassium: 4.6 mEq/L
  • HbA1c: 7.4%
  • Urine albumin-to-creatinine ratio: 580 mg/g

Clinical Image

Diagram illustrating the nephroprotective mechanism of SGLT2 inhibitors: blocking glucose and sodium reabsorption in the proximal tubule increases sodium delivery to the macula densa, activating tubuloglomerular feedback, causing afferent arteriolar constriction, and reducing intraglomerular pressure.

Diagnosis

Diabetic Nephropathy with Persistent Albuminuria despite RAAS Blockade

  • CKD Stage G3b, A3 (high risk for progression)
  • Candidate for SGLT2 inhibitor therapy

Discussion

This case illustrates SGLT2 inhibitor renoprotection:

  • Mechanism Beyond Glucose: The lecture describes how SGLT2 inhibitors provide renoprotection independent of glucose lowering. By blocking sodium-glucose cotransport, they increase sodium delivery to the macula densa, activating tubuloglomerular feedback and reducing intraglomerular pressure.
  • Benefit in Non-Diabetic CKD: The lecture notes that SGLT2 inhibitors benefit patients with CKD regardless of diabetes status. Trials like DAPA-CKD showed benefit in non-diabetic proteinuric CKD.
  • Expected GFR Dip: The lecture describes an expected initial GFR dip of 3-5 mL/min when starting SGLT2 inhibitors. This reflects reduced intraglomerular pressure and predicts long-term benefit.
  • Use Despite Low GFR: Current guidelines support initiating SGLT2 inhibitors down to eGFR 20 mL/min and continuing even lower for renoprotection.

Treatment Plan

  1. Add SGLT2 Inhibitor:
  • Dapagliflozin 10 mg daily OR empagliflozin 10 mg daily
  • Can initiate at eGFR >20 mL/min
  1. Patient Education:
  • Expect initial small GFR drop (3-5 mL/min) - this is beneficial
  • Genital mycotic infections common (maintain hygiene)
  • Drink adequate fluids
  • Hold during sick days (dehydration, major surgery)
  1. Monitoring:
  • Creatinine in 2-4 weeks (expect small rise)
  • Assess for volume depletion
  • Watch for UTI/genital infection symptoms
  1. Medication Adjustments:
  • May need to reduce glipizide dose (reduced hypoglycemia risk is low)
  • Continue metformin (still appropriate at this GFR)
  • Continue ACE inhibitor (synergistic benefit)

Teaching Points

  1. SGLT2 inhibitors activate tubuloglomerular feedback, reducing intraglomerular pressure
  2. Renoprotection is independent of diabetes status
  3. Expected initial GFR dip of 3-5 mL/min predicts long-term benefit
  4. Main adverse effects: genital mycotic infections, volume depletion
  5. Can initiate at eGFR >20 mL/min; continue for renoprotection even lower

Image Reference

For visual reference of renal pharmacology concepts, see:

Learning Points

  1. Loop Diuretic Site: Block NKCC2 in thick ascending limb; account for 25% of sodium reabsorption
  1. Furosemide Bioavailability: Only 50% oral; IV doubles effective dose
  1. ACE Inhibitor Contraindications: Bilateral renal artery stenosis, pregnancy, angioedema history
  1. Acceptable Creatinine Rise: Up to 30% after ACE inhibitor initiation; higher suggests RAS
  1. SGLT2 Mechanism: Tubuloglomerular feedback activation reduces intraglomerular pressure; benefit independent of glucose lowering

All cases for this lecture as Markdown