Acute Kidney Injury & Nephrotoxic Drug Stewardship
The kidneys filter roughly 180 litres of blood a day — making them hyper-sensitive to drops in perfusion and toxic drug accumulation. Catching AKI early saves lives.
KDIGO staging, prerenal/intrinsic/postrenal causes, fluid balance, and the ‘SACKED’ mnemonic — everything you need to protect renal function on shift.
Understanding AKI — Where the Damage Happens
Acute Kidney Injury is a rapid deterioration in kidney function — over hours or days. It stops the body clearing waste, balancing fluids, and regulating electrolytes. Every result set back from the lab is a chance to spot it early. There are three categories of AKI, and knowing which one you’re dealing with changes everything:
- Prerenal AKI (~70% of cases): The kidneys themselves are healthy — they’re just not getting enough blood. Dehydration, bleeding, vomiting, diarrhoea, heart failure, sepsis, low blood pressure. Fix the perfusion, and function often recovers.
- Intrinsic AKI (~25% of cases): Direct damage inside the kidney. Prolonged low blood flow causing Acute Tubular Necrosis (ATN), nephrotoxic drugs, or inflammation inside the kidney tissue. Takes longer to recover — sometimes never fully.
- Postrenal AKI (~5% of cases): Something is blocking the outflow. Enlarged prostate, kidney stones, blocked catheter, pelvic mass. Urine backs up and pressure destroys the nephrons. Relieve the obstruction fast.
KDIGO Staging — How We Measure Severity
We stage AKI using creatinine rises and urine output — the international KDIGO criteria:
- Stage 1: Creatinine 1.5–1.9 × baseline or rise ≥ 26.5 µmol/L or urine output < 0.5 mL/kg/h for 6–12 hours
- Stage 2: Creatinine 2.0–2.9 × baseline or urine output < 0.5 mL/kg/h for ≥ 12 hours
- Stage 3: Creatinine ≥ 3.0 × baseline or ≥ 353.6 µmol/L or dialysis started or urine output < 0.3 mL/kg/h for 24+ hours / anuria 12+ hours
The ‘SACKED’ Mnemonic — Drugs That Damage Kidneys
Your most powerful tool in AKI prevention is reviewing the drug chart. These are the medicines that demand your attention — know them, check them, and question them when results worsen:
S — NSAIDs (Ibuprofen, Naproxen, Diclofenac)
Block the prostaglandins that keep kidney blood vessels open. Suddenly the kidney’s blood supply drops. Action: STOP immediately in AKI — no exceptions.
A — ACE Inhibitors & ARBs (Ramipril, Lisinopril, Candesartan)
Lower pressure inside the filtering units. Great long-term — dangerous when dehydrated or septic. Action: Withhold during illness — ‘sick day rules’ apply. Restart once kidney function recovers.
C — Iodine Contrast Media (CT Scans)
Direct tubular toxicity + reduced blood flow. Action: Check eGFR before scanning. IV fluids before and after reduce risk — hydration is protection.
K — Potassium-Sparing Diuretics (Spironolactone, Amiloride)
Kidneys can’t clear potassium → levels spiral up → heart risk. Action: STOP in AKI. Watch potassium levels closely.
E — Excess Diuretics & Renally Cleared Drugs
Too much furosemide worsens dehydration. Digoxin, lithium, and many others build up to toxic levels. Action: Review fluid status. Check dose adjustments in BNF.
D — Direct Toxins (Gentamicin, Vancomycin, Amphotericin)
Build up inside kidney cells and kill them. Gentamicin is particularly high-risk. Action: Check levels. Shortest possible course. Review daily — is it still needed?
Hyperkalaemia — The Heart-Stopping Complication
Kidneys failing = potassium not leaving. Levels above 5.5 mmol/L are dangerous; above 6.5 is life-threatening. Potassium changes the electrical rhythm of the heart — it can stop without warning. This is what you do:
- PROTECT — IV Calcium Gluconate/Chloride: Doesn’t lower potassium — stabilises the heart muscle in minutes. First move if ECG changes.
- SHIFT — Insulin + Dextrose & Nebulised Salbutamol: Drives potassium out of the blood and into cells. Buys time.
- REMOVE — Resins, Diuretics (if still passing urine), or Dialysis: Gets it out of the body completely. Severe cases need Renal Replacement Therapy.
📖 Trusted Guidelines & References
Standards and updates you can cite and share:
- NICE NG148 — Acute Kidney Injury (updated Oct 2024) — UK framework for prevention, detection, and escalation.
- Think Kidneys (NHS England) — AKI warning scores, medication safety, and patient resources (note: archived, UKKA now leads).
- British National Formulary (BNF) — Renal dose adjustments, gentamicin monitoring, and hyperkalaemia protocols.
Written by: Daniel Hancock, Registered Nurse
Focus: Renal safety, drug stewardship, acute ward care
Published: September 2026 | Last reviewed: September 2026
For: UK student nurses — supervised learning only
⚠️ Always confirm dose adjustments and escalation pathways with the medical team. NICE NG148 is the current UK reference — local trust protocols take precedence.