Renal, Fluids, Electrolytes & Acid-Base · Topic 2 of 22

Chronic Kidney Disease

Renal · kidney injury & replacement

Chronic Kidney Disease

Kidney damage or eGFR below 60 for more than 3 months, staged by GFR and albuminuria; slow it with an ACE inhibitor or ARB plus an SGLT2 inhibitor.

Key numbers

Damage or low eGFR over 3 months> 3 months

Stage by GFR (G1–G5) and albuminuria (A1–A3)G5: eGFR < 15

ACE inhibitor or ARB for albuminuriaAccept SCr ↑ up to 30%

SGLT2 inhibitor if eGFR ≥ 20eGFR ≥ 20

Systolic BP target below 120 if toleratedSBP < 120 mmHg

01 · Defined byDamage or low eGFR over 3 months

CKD = abnormal kidney structure or function for more than 3 months — usually eGFR < 60 mL/min/1.73 m² or albuminuria (ACR ≥ 30 mg/g). After AKI, wait 3 months before diagnosing CKD.

02 · GiveSGLT2 inhibitor if eGFR ≥ 20

Start an SGLT2 inhibitor with eGFR ≥ 20 in CKD with type 2 diabetes, ACR ≥ 200 mg/g or heart failure (suggested for eGFR 20–45 with lower ACR); continue below 20 until dialysis or transplant.

03 · GiveACE inhibitor or ARB for albuminuria

Give an ACE inhibitor or ARB at the maximum tolerated dose for albuminuric CKD (A2–A3 with diabetes; A3, and suggested A2, without). Check creatinine and K⁺ in 2–4 weeks; continue unless creatinine rises > 30%.

Diagnosis & monitoring

Work-up

Stage by GFR (G1–G5) and albuminuria (A1–A3) must knowClassify by cause, GFR category (G1 ≥ 90, G2 60–89, G3a 45–59, G3b 30–44, G4 15–29, G5 < 15) and albuminuria (A1 ACR < 30, A2 30–300, A3 > 300 mg/g).

Systolic BP target below 120 if toleratedTarget systolic BP < 120 mmHg (standardized office measurement) when tolerated; individualize for frailty, fall risk, limited life expectancy or symptomatic orthostatic hypotension.

Management

Orders

Manage hyperkalemia before stopping the RAS inhibitorRAS-inhibitor hyperkalemia is usually managed (diet, diuretics, sodium bicarbonate, patiromer or sodium zirconium cyclosilicate) rather than by stopping the drug; reduce or stop only if these fail.

Finerenone for albuminuric type 2 diabetic CKDAdd a nonsteroidal MRA (finerenone) in type 2 diabetes with eGFR > 25, normal K⁺ and ACR > 30 mg/g despite maximum RAS inhibitor; monitor potassium regularly.

Statin for CKD patients aged 50+Give a statin (or statin plus ezetimibe) to adults ≥ 50 with CKD not on dialysis; under 50, give one with diabetes, coronary disease, prior ischemic stroke or 10-year coronary risk > 10%.

Treat acidosis when bicarbonate falls below 18Treat metabolic acidosis (serum bicarbonate < 18 mmol/L) with oral sodium bicarbonate or more fruits and vegetables, to limit muscle wasting, bone loss and progression; avoid overshooting or volume overload.

Anemia of CKD: replete iron, then ESAAnemia of CKD (from stage 3) is mainly erythropoietin deficiency: keep TSAT > 20% (ferritin > 100 ng/mL off dialysis) and use the lowest ESA dose holding Hb 10–11 g/dL; higher targets raise stroke risk.

Phosphate binders; avoid calcium if hypercalcemicMonitor calcium, phosphate, PTH, 25-OH vitamin D and alkaline phosphatase from G3a; treat hyperphosphatemia with dietary restriction and binders, preferring non-calcium binders (sevelamer) with hypercalcemia or vascular calcification.

Refer to nephrology when eGFR is below 30Refer to nephrology for eGFR < 30, a 5-year kidney failure risk > 3–5% (Kidney Failure Risk Equation), a significant GFR decline, significant albuminuria, hematuria or uncertain cause.

Plan dialysis access when eGFR is 15–20Plan transplant referral and dialysis access when GFR is < 15–20 or 2-year kidney failure risk > 40%; create an AV fistula at least 6 months before expected dialysis.

Start dialysis for symptoms, not a numberStart dialysis for uremic symptoms (anorexia, vomiting, pericarditis, encephalopathy) or volume, potassium or acid–base problems that medical therapy cannot control — usually at GFR 5–10 mL/min/1.73 m².

Hold metformin, RASi, SGLT2i in acute illnessHold metformin, ACE inhibitors/ARBs and SGLT2 inhibitors 48–72 hours before elective surgery or during acute illness (SGLT2i: fasting, surgery, critical illness), and document when to restart them.

Red flags & don'ts

Avoid harm

Never combine ACE inhibitor, ARB or aliskiren avoidAvoid any combination of ACE inhibitor, ARB and direct renin inhibitor: it lowers proteinuria more but raises hyperkalemia and AKI without slowing GFR decline.

Metformin contraindicated below eGFR 30 avoidMetformin is contraindicated with eGFR < 30 and should not be started at eGFR 30–45; avoid NSAIDs in CKD, and dose penicillins, cephalosporins, fluoroquinolones, vancomycin and digoxin for GFR.

AKI or CKD?

Commonly confused

Time course	Creatinine rising over days
Kidney size on ultrasound	Normal or enlarged
After an AKI episode	Not yet CKD — reassess at 3 months

More detail

Reference

Show 7 reference facts

Small kidneys (< 10 cm) with thin, echogenic cortex mean CKD; normal or large kidneys suggest AKI or a large-kidney CKD (diabetes, polycystic disease, myeloma, amyloid). Small fibrotic kidneys are not biopsied.

Estimate GFR with the race-free CKD-EPI 2021 creatinine equation; add cystatin C (eGFRcr-cys) when creatinine is unreliable (extreme muscle mass, amputation) or dosing accuracy matters.

An eGFR change beyond ±20% is likely real, and a fall ≥ 30% after starting a hemodynamically active drug warrants evaluation (volume, NSAIDs, diuretics, renal artery stenosis).

Uremic bleeding rarely needs treatment; when it does, give desmopressin 0.3–0.4 mcg/kg IV (max 20 mcg), cryoprecipitate or conjugated estrogens.

Restrict sodium to < 2 g/day with hypertension, edema or proteinuria; protein 0.8 g/kg/day for eGFR < 60 without frailty; restrict potassium individually (rarely needed when eGFR > 30).

Diabetic nephropathy is the most common cause of CKD in the United States, followed by hypertensive nephrosclerosis and glomerulopathies.

With GFR < 30, give gadolinium only as an ACR group II (or III) agent to limit nephrogenic systemic fibrosis.

Pearl

Stage by Cause, GFR and Albuminuria — then protect the kidney with RASi plus SGLT2i.

Sources · Levin A et al. Executive summary of the KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of CKD. Kidney Int 2024;105:684–701 · KDIGO 2024 CKD Guideline — Top 10 Takeaways on Management for Primary Care Physicians · KDIGO 2024 CKD Guideline — Top 10 Takeaways on Evaluation for Primary Care Physicians · KDIGO — CKD Evaluation and Management guideline page (2024 guideline; 2027 medications update in public review) · Merck Manual Professional — Chronic Kidney Disease · Metformin hydrochloride tablets prescribing information — DailyMed · Merck Manual Professional — Hemodialysis · Starter sheet built from the verified AGACNP fact map (facts reviewed 2026-10-15).