GFR-Based Stages (KDIGO 2024)

Albuminuria-Based Categories (Heat Map)

Clinical Pearl: Combination of GFR + albuminuria stage predicts progression risk. A patient with G3a/A3 (eGFR 45–59 + UACR >300 mg/g) has higher risk than G3a/A1 despite same GFR.

Key Assessments at CKD Diagnosis

• Urine albumin-to-creatinine ratio (UACR) (gold standard; repeat if initial >300 mg/g)
• Blood pressure (standardized office measurement; home/ambulatory readings complement assessment and are not automatically assigned the office <120 target)
• Metabolic panel: K, PO₄, HCO₃⁻, Ca, Mg
• Bone-specific markers: Alkaline phosphatase, PTH, 25-OH vitamin D
• Lipid panel
• Hemoglobin/hematocrit (baseline for anemia management)
• Renal imaging (ultrasound or CT to assess echogenicity, size, exclude hydronephrosis)

Tier 1: SGLT2 Inhibitors (Eligibility-Based Therapy)

Recommendation: Apply the CKD, T2D, albuminuria, and HF criteria above. Check the actual product label and the disease context; major CKD trials did not establish benefit for every etiology, transplant population, or dialysis setting.

Key Evidence — DAPA-CKD: Dapagliflozin reduced the primary composite of sustained ≥50% eGFR decline, kidney failure, or kidney/CV death: HR 0.61 (39% relative reduction), median 2.4 years. The CV-death/HF-hospitalization secondary composite had HR 0.71 (29% relative reduction). A hazard ratio of 0.61 is not a 61% risk reduction. Primary trial.

• EMPA-KIDNEY trial: Empagliflozin 10 mg daily in CKD (non-diabetes cohort ≥50% of subjects)
  • Primary outcome: kidney-disease progression or cardiovascular death, HR 0.72 (28% relative reduction), median 2.0 years.
  • All-cause mortality did not differ significantly; do not claim a proven 25% reduction. Primary trial.

Mechanism: Proximal tubule glucose/sodium reabsorption inhibition → natriuresis, reduced intraglomerular pressure, anti-inflammatory effects.

Dosing: - Dapagliflozin: 10 mg daily (empagliflozin: 10 mg daily) - Continue even if eGFR falls below 20 mL/min/1.73 m² - Caution: genitourinary infections (5–8% increased incidence); counsel patients on symptoms

Side Effects: Euglycemic DKA (rare, <1%), genital infections, volume depletion (caution in elderly).

Tier 2: RAAS Blockade (ACE-I/ARB)

Recommendation: Initiate ACE inhibitor or ARB if albuminuria present (UACR ≥30 mg/g) [1].

Mechanism: Block aldosterone and angiotensin II → reduce proteinuria, lower intraglomerular pressure, anti-inflammatory.

Target: Maximum tolerated dose (not just minimum therapeutic dose).

Monitoring: Check creatinine and potassium within 2–4 weeks after starting or increasing an ACE inhibitor/ARB, sooner when risk is high. A hemodynamic creatinine rise reflects reduced efferent arteriolar tone, not afferent dilation. A rise >30% within 4 weeks prompts assessment for depletion, interacting drugs, or renovascular disease. Manage hyperkalemia when possible to preserve indicated therapy; hold/reduce when it remains uncontrolled or symptomatic hypotension occurs.

Caution: - Triple whammy: ACE-I/ARB + NSAID + diuretic → acute renal failure - Contraindicated: Pregnancy, prior angioedema, K⁺ >6.0 mEq/L

Tier 3: Finerenone (Non-Steroidal Mineralocorticoid Receptor Antagonist)

Recommendation: For CKD/T2D, finerenone is appropriate when eGFR is ≥25, potassium permits initiation, and albuminuria persists despite a maximally tolerated ACE inhibitor or ARB. The CKD/T2D indication should not be generalized to any albuminuric CKD; separate HF indications require their own phenotype and label assessment.

Key Evidence: - FIDELIO-DKD trial [3]: Finerenone 10 mg daily (titrate to 20 mg) in CKD + T2D - Primary outcome: 18% RRR in composite of ≥40% GFR decline, ESRD, or renal death - Cardiovascular outcome: 14% RRR

• FIGARO-DKD trial: Finerenone in earlier-stage CKD + T2D
  • Consistent benefit across CKD stages G2–G4

Mechanism: Selective MRA (non-steroidal; hyperkalemia remains a clinically important risk) → anti-inflammatory, reduces fibrosis.

Dosing for CKD/T2D: The US label uses 10 mg daily at eGFR 25–<60 and 20 mg daily at eGFR ≥60; initiation is not recommended below 25. Do not initiate when potassium >5.0 mEq/L. Adjust by potassium, eGFR, and the product-specific algorithm.

Monitoring: Check potassium/eGFR at baseline and potassium about 4 weeks after starting or changing the dose; continue periodic monitoring, commonly every 4 months when stable in the KDIGO pathway. Hold finerenone if potassium >5.5 and consider restart when ≤5.0 according to the label. US prescribing information.

Side Effects: Hyperkalemia (more common if eGFR <30; incidence 10–15%), volume depletion, hypotension.

Tier 4: GLP-1 Receptor Agonists (If Diabetes + Obesity)

Recommendation: For T2D patients with CKD who require glucose control and have weight loss indication.

Evidence: In FLOW, semaglutide reduced the primary composite kidney/CV-death outcome in patients with type 2 diabetes and CKD [4]. This trial does not establish a fixed additive benefit from combining every kidney-protective drug class.

Advantage: Weight loss (unlike other antihyperglycemics), reduced cardiovascular events.

Monitor: Pancreatitis risk (low but real), retinopathy changes if diabetic.

Target Blood Pressure

KDIGO target: For many adults with hypertension and nondialysis CKD, target systolic BP <120 mmHg when tolerated using standardized office measurement. This is not a universal home-BP target. Individualize for orthostasis, frailty, limited life expectancy, and treatment harms; use home/ambulatory measurements to complement office assessment.

Evidence: SPRINT tested intensive versus standard systolic BP targets in selected high-risk adults without diabetes. The primary benefit was a cardiovascular composite; it was not a 25% reduction in ESRD/death. Apply standardized measurement and consider tolerance, AKI, and electrolyte risks. SPRINT primary report.

Home Blood Pressure Monitoring

Preferred over office BP (office readings overestimate; home BP more predictive of progression).

Protocol: - Measure in morning (before medications) and evening - Record 3 readings, separated by 1–2 minutes, on 3+ days/week - Use validated automated device (avoid aneroid manometers) - Target: Use the clinician-agreed home target; do not directly transfer the standardized-office <120 target

Antihypertensive Strategy

First-line (for CKD with albuminuria): 1. ACE-I or ARB (proteinuria reduction) 2. Add SGLT2i (cardiac + renal benefit) 3. Add finerenone if persistent albuminuria/progression

Add second agent if BP target not met: - Calcium channel blocker (amlodipine, diltiazem): reduces proteinuria, no adverse metabolic effects - Thiazide-type diuretic (chlorthalidone, hydrochlorothiazide): caution in K⁺ disturbances

Avoid (or use with extreme caution): - Direct vasodilators (hydralazine) as monotherapy: reflex tachycardia, hypertensive tolerance - Alpha-blockers: no renal protection; increased HF risk

Chronic Kidney Disease–Mineral Bone Disorder (CKD-MBD)

Assess calcium, phosphate and PTH trends together, with CKD stage and treatment history. There is no single PTH target for all nondialysis CKD. Address persistently elevated phosphate with dietary counseling and, when indicated, phosphate binders such as sevelamer, lanthanum or calcium-based agents. Patiromer is a potassium binder, not a phosphate binder. Avoid routine active vitamin D solely for modest PTH elevation in nondialysis CKD; specialist management depends on severity and trends. KDIGO 2017 CKD-MBD guideline.

Anemia in CKD

Etiology: Erythropoietin (EPO) deficiency (85%) + chronic inflammation + reduced RBC lifespan.

Hemoglobin Target: For adults treated with an ESA, KDIGO 2026 recommends a target below 11.5 g/dL. Initiation and the working range are individualized; nondialysis CKD does not have a universal Hb <10 initiation rule. Final KDIGO 2026 anemia guideline.

Treatment Pathway: Evaluate iron status, B12/folate deficiency, bleeding, hemolysis, inflammation, and other causes before attributing anemia to CKD. For nondialysis CKD/PD, KDIGO 2026 suggests iron initiation with ferritin <100 ng/mL and TSAT <40%, or ferritin 100–<300 and TSAT <25%; for HD, ferritin ≤500 and TSAT ≤30%. Routine iron is generally withheld if ferritin >700 or TSAT ≥40%, and suspended during systemic infection. Oral or IV iron in nondialysis CKD is chosen by severity, response, tolerance, access, and preference—not eGFR alone; consider switching after an inadequate 1–3-month oral trial. Ferritin 600/TSAT18% does not automatically mandate IV iron in nondialysis CKD. ESA initiation weighs symptoms, transfusion risk, and treatment harms; use local labeling for ESA/HIF-PHI eligibility rather than treating the classes as interchangeable.

Metabolic Acidosis

Mechanisms: Reduced ammonia excretion, impaired H⁺ secretion, accumulation of organic acids.

Assessment: Serum bicarbonate is a chemistry measurement, not a blood pH. Confirm persistent metabolic acidosis and its cause before treatment [5].

Management: Individualize dietary and pharmacologic measures for clinically important acidosis. Monitor bicarbonate, blood pressure, potassium and fluid status during alkali treatment. Patiromer treats hyperkalemia; it is not an alkali replacement [5].

Evidence limit: Alkali treatment decisions should address the severity of acidosis and patient risks; a fixed 30% reduction in CKD progression is not established for all patients.

Timing of Referral to Nephrology

KDIGO Recommendations: - G4 (eGFR 15–29): Refer for CKD management intensification, education, vascular access planning - G5 (eGFR <15): Prepare for renal replacement therapy (RRT) choice and timing

Modality Selection (Patient Education Timing: G3b–G4)

Vascular Access Planning (G4 Stage)

Timing: Initiate access planning when eGFR ~20 mL/min/1.73 m² to allow maturation.

Preferred Hierarchy: 1. Arteriovenous fistula (AVF): Autologous vein-to-artery; lowest infection/stenosis risk; 6–12 weeks maturation - Forearm (cephalic-radial preferred) or upper arm (brachial-axillary) 2. Arteriovenous graft (AVG): Synthetic prosthetic; shorter maturation (2–4 weeks); higher complication rate 3. Central venous catheter (CVC): Temporary access only; highest infection/thrombosis risk; should not be chronic access

Nephrologist’s Role: Refer to vascular surgeon for fistula evaluation; optimize BP, avoid BP draws/IV lines in non-fistula arm.

Advance Care Planning (G4–G5)

• Discuss RRT options (HD vs PD vs conservative care)
• Address goals of care, quality-of-life expectations, family preferences
• Document wishes if progression to G5 and RRT initiation needed
• Palliative care consultation if considering conservative (non-dialytic) management

CKD + Heart Failure

Unique Challenge: Diuretics reduce BP/perfusion → risk of AKI progression; RAAS blockade may worsen hyperkalemia.

Strategy: Use SGLT2 therapy when the HF/CKD indication and product label fit; outcome benefits differ by trial and phenotype. Treat congestion with an appropriate diuretic and reassess perfusion, kidney function, and electrolytes. For HFrEF, spironolactone/eplerenone have established indication-specific evidence; do not automatically substitute finerenone because CKD is present. Finerenone requires its own CKD/T2D or eligible HF indication, potassium monitoring, and avoidance of unnecessary overlapping MRA therapy.

CKD + Diabetes

Layer kidney-protective therapies when the patient meets each treatment indication and can tolerate monitoring. Do not assume that individual trial effect sizes can be added together [5].

Goals: - Tight glycemic control (HbA₁c 7–8%); avoid hypoglycemia (↑ CV risk in CKD) - Initiate SGLT2i immediately at DM diagnosis if eGFR ≥20 - Add finerenone if albuminuria persists on ACE-I/ARB + SGLT2i - GLP-1 RA for additional glycemic and cardiometabolic benefit

CKD + Obesity

Advantage: SGLT2i provide weight loss (2–3 kg over 6 months); GLP-1 RA provide greater weight loss (4–8 kg).

Recommendation: Prefer these agents in obese CKD patients; defer to these drugs as primary weight-loss therapy.

Warning 1: Hyperkalemia in Advanced CKD

RAAS blockers and finerenone can increase potassium; SGLT2 inhibitors are not potassium-sparing drugs and should not be grouped with them mechanistically. Advanced CKD, interacting medicines, and acute illness increase monitoring needs. Assess each treatment’s eligibility and potassium response.

Management: Use drug-specific monitoring and hold/restart rules; do not wait for potassium >6.0 before applying the finerenone label threshold. Review supplements, potassium salt substitutes, constipation, acidosis, and interacting medicines. Potassium binders may help preserve indicated therapy in selected patients; dietary advice should address actual sources and nutritional needs rather than a blanket plant-food ban.

Warning 2: Acute Decline in GFR on ACE-I/ARB

30% SCr rise acceptable after initiation (due to hemodynamic changes). However, >30% rise or rise >0.5 mg/dL warrants reassessment: - Rule out AKI (dehydration, infections, NSAIDs) - Check renal artery stenosis if sudden decline - Consider dose reduction if marked hyperkalemia

Warning 3: Volume Overload in Dialysis Preparation

Paradoxically, CKD G4 can present with volume expansion (inability to excrete Na + H₂O) while still maintaining systolic hypertension. This requires: - ACE-I/ARB + loop diuretics (to reduce volume + BP) - Sodium restriction (<2000 mg/day) - Fluid restriction if SIADH or severe hyponatremia