Acute Kidney Injury Nursing Guide 2026: Staging, Causes, and Management

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Contents: AKI Staging (KDIGO) Types of AKI Nursing Assessment Management Priorities Nephrotoxin Avoidance Dialysis Indications and Nursing NCLEX High-Yield

AKI Staging (KDIGO Criteria)

AKI is defined by the KDIGO (Kidney Disease Improving Global Outcomes) criteria as ANY of the following:

Serum creatinine rise ≥0.3 mg/dL within 48 hours, OR
Serum creatinine rise ≥1.5x baseline within 7 days, OR
Urine output <0.5 mL/kg/hr for ≥6 consecutive hours

Stage	Creatinine Criteria	Urine Output
Stage 1	1.5–1.9x baseline within 7 days OR ≥0.3 mg/dL rise within 48 hr	<0.5 mL/kg/hr for 6–12 hr
Stage 2	2.0–2.9x baseline	<0.5 mL/kg/hr for ≥12 hr
Stage 3	≥3.0x baseline OR creatinine ≥4.0 mg/dL OR initiation of renal replacement therapy	<0.3 mL/kg/hr for ≥24 hr OR anuria for ≥12 hr

Urine output is a more SENSITIVE early indicator of AKI than creatinine. Creatinine rises lag kidney injury by hours. A urine output <30 mL/hr (<0.5 mL/kg/hr for a 60 kg patient) requires immediate assessment.

Three Categories of AKI

Category	Mechanism	Common Causes	Key Indicators
Prerenal AKI (~55%)	Decreased renal perfusion without intrinsic kidney damage; kidneys are functionally intact but under-perfused; REVERSIBLE with fluid resuscitation	Hypovolemia (dehydration, hemorrhage, burns), cardiogenic shock, septic shock, hepatorenal syndrome, NSAIDs/ACE inhibitors reducing GFR, renal artery stenosis	BUN/Cr ratio >20:1; urine Na <20 mEq/L; urine specific gravity >1.020; FENa <1%; concentrated urine (kidneys trying to conserve); responds to fluid challenge
Intrinsic (Intrarenal) AKI (~40%)	Direct damage to renal parenchyma (tubules, glomeruli, interstitium, vasculature)	ATN (acute tubular necrosis — most common intrinsic cause; ischemic or nephrotoxic); contrast nephropathy; aminoglycoside toxicity; glomerulonephritis; interstitial nephritis (NSAIDs, penicillin); rhabdomyolysis	BUN/Cr ratio <15:1 (creatinine rises proportionally more); urine Na >40 mEq/L (kidneys can't reabsorb); FENa >2%; muddy brown casts (ATN); does NOT respond to fluids alone
Postrenal AKI (~5%)	Obstruction to urine flow from the collecting system outward; relief of obstruction is curative	BPH (most common in elderly men), kidney stones, tumors (cervical, prostate, bladder), clots, strictures, neurogenic bladder, inadvertent ureteral ligation during surgery	Bilateral hydronephrosis on ultrasound; symptoms of obstruction (difficulty voiding, distended bladder); immediate improvement after catheterization or stent placement

Nursing Assessment in AKI

Hourly urine output: Document and report <0.5 mL/kg/hr (<30–50 mL/hr for average adult); keep strict I&O
Daily weights: Same scale, same time; fluid overload is the immediate consequence of AKI
Laboratory trends: BMP/CMP daily or BID; creatinine, BUN, potassium (hyperkalemia is life-threatening), bicarbonate, phosphorus
Vital signs: BP (hypertension from fluid overload; hypotension from sepsis/prerenal); assess for JVD, edema, crackles
Neurological: Uremic encephalopathy — confusion, asterixis ("flapping tremor" when hands extended), nausea, lethargy in severe AKI
Cardiac: EKG for hyperkalemia (peaked T waves, widened QRS); continuous monitoring if K+ >5.5
Fluid status: Avoid fluid overload (worsens pulmonary edema) AND fluid deficit (worsens prerenal component)

AKI Management Priorities

Optimize Renal Perfusion

Treat underlying cause aggressively: fluid resuscitation for hypovolemia; treat sepsis; revascularize if indicated
Avoid hypotension (MAP >65 mmHg minimum; MAP >80 in CKD or hypertensive patients)
STOP or hold nephrotoxic medications (see below)
HOLD contrast agents; if contrast required, pre-hydrate and minimize contrast volume

Manage Complications

Complication	Treatment
Hyperkalemia	Calcium gluconate (cardiac stabilization); insulin + D50 (shift K+ into cells); sodium bicarbonate; kayexalate or patiromer (excretion); dialysis if >6.5 or symptoms
Fluid overload	Fluid restriction; loop diuretics (furosemide) if patient still makes urine; dialysis if refractory
Metabolic acidosis	Treat underlying cause; sodium bicarbonate if pH <7.10 or HCO3 <10; dialysis
Uremia	Protein restriction (controversial); dialysis is definitive for symptomatic uremia
Hypertension	Antihypertensives (avoid ACE inhibitors/ARBs acutely — reduce GFR); fluid removal via dialysis or diuretics

Nephrotoxin Avoidance

AKI patients and those at risk (elderly, CKD, diabetes, sepsis, dehydration) should have ALL nephrotoxic agents reviewed and discontinued or minimized:

Nephrotoxin	Mechanism	Nursing Action
NSAIDs (ibuprofen, ketorolac, naproxen)	Inhibit prostaglandin-mediated renal afferent arteriole dilation → reduce GFR; especially dangerous in low-perfusion states	AVOID in AKI or at-risk patients; hold if creatinine rising; discontinue and use acetaminophen instead
ACE inhibitors / ARBs (lisinopril, losartan)	Block angiotensin II-mediated efferent arteriole constriction → reduce GFR in renovascular/volume-depleted states	Hold in acute AKI, sepsis, severe dehydration, or bilateral renal artery stenosis; restart when hemodynamically stable
IV Contrast dye	Direct tubular toxicity + renal vasoconstriction; highest risk in CKD, diabetes, dehydration	Pre-hydrate with IV NS before and after contrast; minimize contrast volume; use iso-osmolar contrast; hold metformin 48 hr
Aminoglycosides (gentamicin, tobramycin)	Direct tubular toxicity; accumulate in renal cortex; dose-dependent; non-oliguric ATN	Once-daily dosing preferred (less tubular accumulation); monitor trough levels; avoid concurrent nephrotoxins; assess renal function frequently; hydration
Vancomycin	Nephrotoxicity especially with concurrent aminoglycosides or contrast; tubular toxicity	Monitor vancomycin AUC/MIC (AUC-guided dosing replaces trough monitoring per 2020 ASHP guidelines); avoid concurrent aminoglycosides; optimize hydration

Dialysis Indications (AEIOU) and Nursing

Indications for Emergency Dialysis — AEIOU Mnemonic

A — Acidosis: Severe metabolic acidosis (pH <7.10) refractory to bicarbonate therapy
E — Electrolytes: Severe hyperkalemia (K+ >6.5 or symptomatic/EKG changes) refractory to medical management
I — Intoxication: Certain toxic ingestions (methanol, ethylene glycol, lithium, salicylates, theophylline)
O — Overload: Severe fluid overload (pulmonary edema) refractory to diuretics
U — Uremia: Symptomatic uremia (encephalopathy, pericarditis, bleeding, uremic neuropathy)

Hemodialysis (HD) Nursing

Access: AV fistula (preferred long-term), AV graft, or temporary dialysis catheter (Mahurkar/Quinton)
Pre-dialysis: weight, BP, labs (BMP, CBC), access assessment (fistula thrill/bruit), assess for fluid overload
During dialysis: monitor BP every 30 min (hypotension is most common complication), HR, any symptoms
Post-dialysis: apply pressure to fistula for 5–15 min; weight; reassess labs; BP (may be hypotensive post-dialysis)
AV fistula rules: NO BP cuffs, NO IV access, NO blood draws from the fistula arm; assess thrill and bruit every shift

NCLEX High-Yield Points

First sign of AKI: decreased urine output (<0.5 mL/kg/hr = <30 mL/hr for average adult)
Prerenal: BUN/Cr >20:1; concentrated urine; responds to fluids. Intrinsic: BUN/Cr <15:1; muddy brown casts; does NOT respond to fluids
Postrenal: BPH most common cause in elderly men; immediate relief with catheterization
AEIOU = indications for emergency dialysis: Acidosis, Electrolytes (K+), Intoxication, Overload, Uremia
AV fistula arm: NO BP, NO IV, NO blood draws; assess bruit (auscultate) and thrill (palpate) each shift
NSAIDs and ACE inhibitors/ARBs: hold in AKI (both reduce GFR)
Uremic encephalopathy signs: asterixis (flapping tremor), confusion, nausea — indicates severe AKI requiring dialysis
Creatinine and BUN lag: urine output drops BEFORE creatinine rises significantly; monitor both

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Acute Kidney Injury Nursing Guide 2026: Staging, Causes, and Management

AKI Staging (KDIGO Criteria)

Three Categories of AKI

Nursing Assessment in AKI

AKI Management Priorities

Optimize Renal Perfusion

Manage Complications

Nephrotoxin Avoidance

Dialysis Indications (AEIOU) and Nursing

Indications for Emergency Dialysis — AEIOU Mnemonic

Hemodialysis (HD) Nursing

NCLEX High-Yield Points

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