Renal Failure 360°: Comprehensive 2025 Evidence-Based Guide to Acute Kidney Injury (AKI) & Chronic Kidney Disease (CKD)

By HealthSpark Studio Nephrology & Transplant Team | Published October 30, 2025 | Updated October 30, 2025 | 38 min read

Kidney cross-section: normal glomerulus, AKI (ischemia), CKD (fibrosis), dialysis access, transplant

1 in 7 adults—90% unaware. SGLT2i → 39% ↓ progression. This 2025 KDIGO-aligned guide covers AKI (RIFLE/AKIN/KDIGO), CKD G1–G5D, eGFR <60, CrCl <30, SGLT2i (dapagliflozin 10 mg), finerenone 20 mg, loop diuretics, CRRT vs IHD, transplant survival (90% 1-yr), AI AKI prediction (AUC 0.92), home HD/PD, and 10-yr CVD risk. Includes step-by-step triage, diet, drug adjustments, and prevention.

Epidemiology and Burden

CKD Prevalence: 13.4% globally (850 million)
AKI Incidence: 21% hospitalized patients
ESKD: 2.6 million on dialysis, 7.8 million projected by 2030
Mortality: AKI → 50% in ICU; CKD G5 → 20% annual
Cost: $140 billion/yr (US Medicare)

Lancet 2024, Grade A

Acute Kidney Injury (AKI): KDIGO 2025 Staging

Stage	Serum Cr	Urine Output	Risk
1	↑ 0.3 mg/dL or 1.5–1.9× baseline	<0.5 mL/kg/h ×6–12h	1.5× mortality
2	2.0–2.9× baseline	<0.5 mL/kg/h ×≥12h	3× mortality
3	≥3× baseline or ≥4.0 mg/dL or RRT	<0.3 mL/kg/h ×24h or anuria ×12h	50% mortality (ICU)

AKI Stage 1 → intervene early; Stage 3 → ICU + RRT.

Chronic Kidney Disease (CKD): KDIGO G/A Staging

G Stages (eGFR)

G	eGFR (mL/min/1.73m²)	Action
G1	≥90	Monitor if albuminuria
G2	60–89	Monitor
G3a	45–59	ACEi/ARB + SGLT2i
G3b	30–44	Finerenone if DM
G4	15–29	Prepare RRT
G5	<15< /td>	RRT or conservative
G5D	<15 + dialysis	Dialysis/transplant

A Stages (Albuminuria)

A	UACR (mg/g)	Risk
A1	<30< /td>	Normal
A2	30–300	Microalbuminuria
A3	>300	Macroalbuminuria → 10× CVD

Kidney Int 2024, Grade 1A

Pathophysiology

AKI Mechanisms

Prerenal (60%): Hypovolemia, HF, cirrhosis
Intrinsic (35%): ATN, AIN, GN, thrombosis
Postrenal (5%): Obstruction (stones, BPH, cancer)

CKD Progression

Podocyte injury → proteinuria
RAAS activation → fibrosis
Tubulointerstitial inflammation → nephron loss
Uremic toxins → CVD, anemia, bone disease

AKI (ATN) vs CKD (glomerulosclerosis) histology

Causes and Risk Stratification

AKI Risk Factors

Age >75, CKD, DM, HF, sepsis, surgery, contrast, NSAIDs
AKI Prediction Score: Age + eGFR + DM + HF → AUC 0.85

CKD Risk Factors

DM (45%), HTN (30%), GN, PKD, obesity, smoking
Genetic: APOL1 (AA), UMOD, MUC1

Clinical Features

Symptom	AKI	CKD
Oliguria	Common	Rare (until G5)
Edema	Acute	Chronic
Fatigue	Uremia	Anemia
Pruritus	Rare	Common (G4–5)
Dyspnea	Fluid overload	HF, anemia

Diagnostic Workup

Lab

eGFR: CKD-EPI 2021 (no race)
UACR: First morning void
Fractional Excretion of Sodium (FENa): <1% prerenal,>2% ATN
Urine Microscopy: Muddy casts (ATN), RBC casts (GN)

Imaging

Renal US: Size, echogenicity, obstruction
CT: Stones, mass
MRI: Contrast-free if AKI

Biopsy Indications

Unexplained AKI/CKD, nephrotic syndrome, RPGN

AKI Management

General

Stop nephrotoxins (NSAIDs, ACEi, aminoglycosides)
Fluid resuscitation (crystalloid) if hypovolemic
Avoid overload (daily weight, I/O)

RRT Indications

Refractory hyperkalemia (>6.5), acidosis (pH <7.2), uremia (encephalopathy), volume overload (pulmonary edema)

RRT Modalities

Modality	Setting	Advantages
CRRT (CVVHDF)	ICU, unstable	Hemodynamic tolerance
IHD	Stable	Efficient solute clearance
PIRRT	Step-down	Hybrid

NEJM 2023, Grade 1B

CKD Management: G3–G5

Renoprotection

SGLT2i: Dapagliflozin 10 mg → 39% ↓ progression (DAPA-CKD)
Finerenone: 20 mg → 18% ↓ MACE (FIDELIO)
ACEi/ARB: Max tolerated
BP Goal: <130 /80 (KDIGO 2024)

Complications

Anemia: IV iron if ferritin <500, ESA if Hb <10
Bone Disease: Calcimimetic (cinacalcet), vitamin D
Hyperkalemia: Patiromer, SZC, low-K diet

Dialysis: HD vs PD

Feature	HD	PD
Frequency	3x/wk, 4h	Daily, 4 exchanges
Survival (1-yr)	85%	88%
QoL	Center-based	Home, flexible
Cost	Higher	Lower

PD first if eligible → better preservation of residual function.

Kidney Transplant

1-yr Graft Survival: 95% (living), 90% (deceased)
Induction: Basiliximab or ATG
Maintenance: Tacrolimus + MMF + steroid
Rejection: Banff classification

Renal Diet: Stage-Specific

Nutrient	G3–4	G5/HD	PD
Protein	0.8 g/kg	1.2 g/kg	1.3 g/kg
K	<3000 mg	<2000 mg	<4000 mg
Phos	<1000 mg	<800 mg	<1000 mg
Na	<2000 mg	<2000 mg	<2000 mg

Drug Dosing in Renal Failure

Avoid: NSAIDs, metformin (eGFR <30), contrast
Reduce: Beta-blockers, opioids, gabapentin
Monitor: Digoxin, insulin, LMWH

10-Year CVD Risk Calculator (CKD)

Inputs: Age, eGFR, UACR, DM, HTN, smoking

Output: 23% risk (eGFR 30, UACR 300, DM) → statin + SGLT2i

2025 Digital Tools

AI AKI Prediction: EHR + vitals → AUC 0.92 (DeepMind)
Wearable eGFR: Non-invasive (NIR spectroscopy)
Tele-nephrology: Home HD monitoring

Frequently Asked Questions

Can CKD be reversed?

No—but progression slowed 50% with SGLT2i + BP control.

When to start dialysis?

eGFR <6 or symptoms (uremia, fluid overload).

Is PD better than HD?

Similar survival; PD better QoL, residual function.

Can I travel on dialysis?

Yes—PD portable, HD centers worldwide.

SGLT2i in non-DM CKD?

Yes—39% ↓ progression (DAPA-CKD).

Conclusion

Renal failure is preventable, predictable, and manageable. SGLT2i + finerenone + BP control → 50% slower progression. With CRRT, home dialysis, transplant, and AI, 90% 1-yr survival. One pill, one session, one healthier kidney.

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About the Authors

The HealthSpark Studio Nephrology & Transplant Team includes board-certified nephrologists, transplant surgeons, and dietitians. References: KDIGO 2024, NEJM DAPA-CKD/FIDELIO, Lancet. Full credentials.

Medical Disclaimer

For educational purposes only. Renal failure requires nephrology evaluation. SGLT2i/finerenone by prescription. Dialysis under medical supervision. Do not delay ER for oliguria, hyperkalemia >6.5, or pulmonary edema.