Case Study — Renal
Hyperkalemia & AKI NGN Case Study
A Next Gen NCLEX-style unfolding case. Read each step, commit to your own answer — out loud or on paper — and only then reveal ours. The six steps mirror the NCSBN Clinical Judgment Measurement Model exactly as the exam tests it.
15 min activity · Renal
Educational use only. This case is a learning exercise with simplified values, not a treatment protocol — real hyperkalemia care follows provider orders and your facility’s protocol, including its specific medication sequence and dialysis criteria. This material supports nursing education and exam review. It is not medical advice and is not a substitute for clinical judgment, institutional policy, or medical direction. Always follow facility protocols and current provider orders.
The Scenario
1130, ED: Mr. Whitfield, 67, with heart failure and gout, comes in for three days of vomiting and diarrhea from “something I ate,” now with profound weakness — “my legs feel like wet sand.” Home medications: lisinopril, spironolactone, and naproxen he’s been taking around the clock for a gout flare this week. He “hasn’t peed much since yesterday.”
1145 Assessment & Labs
- HR 58 · BP 104/62 · RR 18 · SpO₂ 97% RA · Temp 36.7°C
- Dry mucous membranes, poor skin turgor; generalized weakness, 3/5 in the legs
- K⁺ 6.8 · Na⁺ 134 · BUN 88 · creatinine 3.1 (baseline 1.1 three months ago) · glucose 110
- Monitor shows bradycardia with tall, peaked T waves; 12-lead ordered
Step 1 — Recognize Cues
Which findings are most relevant — and which matter most right now? List the cues you would flag before revealing.
▸Reveal answer
The life threat: K⁺ 6.8 with EKG changes — peaked T waves and bradycardia. Potassium this high with cardiac effects can degrade to a sine wave and arrest with little warning. The leg weakness is the same story told by skeletal muscle.
The kidney story: creatinine tripled from baseline (3.1 from 1.1), BUN 88, and minimal urine output — acute kidney injury, with a BUN:Cr ratio and an exam (dry, hypotensive-for-him, three days of GI losses) that scream volume depletion.
The medication cue everyone misses: ACE inhibitor + potassium-sparing diuretic + NSAID — the “triple whammy.” Each impairs renal perfusion or potassium excretion; together, on a dehydrated patient, they built this lab panel.
Step 2 — Analyze Cues
Connect the mechanism: how did three days of gastroenteritis become a potassium of 6.8? And what type of AKI is this?
▸Reveal answer
Prerenal AKI (most supported): vomiting and diarrhea drained his volume; the NSAID constricted the afferent arteriole and the ACE inhibitor dilated the efferent — together they stripped the glomerulus of perfusion pressure exactly when it had no volume reserve. Low flow → falling GFR → BUN and creatinine climb, urine output falls.
The potassium arithmetic: failing filtration stops potassium excretion; spironolactone blocks what excretion remains; the ACE inhibitor suppresses aldosterone further. Intake continued, elimination stopped — serum potassium climbs.
Worth excluding: intrinsic AKI (ATN from prolonged hypoperfusion — possible if this has cooked too long; urine studies help), postrenal obstruction (bladder scan — quick and free, especially in an older man), and pseudohyperkalemia from a hemolyzed sample — but with EKG changes, you treat first and re-verify in parallel, never wait.
Step 3 — Prioritize Hypotheses
Rank the problems. What dies first, and what fixes the underlying machine?
▸Reveal answer
1. The myocardium — hyperkalemia with EKG changes is the immediate killer; everything else waits behind it.
2. The volume deficit — it is both a circulation problem and the cause of the AKI; restoring perfusion is how the kidneys come back online and start excreting potassium again.
3. The offending medications — all three are held today; this is the relapse-prevention move.
NGN logic: stabilize what’s lethal (the heart), treat the cause (volume), remove the perpetuating factors (the triple whammy) — three tiers, worked nearly in parallel but prioritized in exactly that order.
Step 4 — Generate Solutions
Build the treatment plan in three buckets: protect, shift, remove. What goes in each — and what does each one actually do to the potassium?
▸Reveal answer
Protect (does nothing to the K⁺ level): IV calcium gluconate stabilizes the cardiac membrane within minutes — it buys time, nothing more. With EKG changes, it is always first.
Shift (hides K⁺ inside cells — temporary): IV regular insulin with dextrose (the workhorse) and nebulized albuterol drive potassium intracellularly for a few hours. The level falls; the total body burden doesn’t.
Remove (actually lowers total potassium): restore urine output with isotonic fluids for his prerenal state (working kidneys are the best potassium remover), potassium-binding agents per orders, and dialysis if he stays oliguric and hyperkalemic despite everything.
Plus the housekeeping that prevents round two: hold lisinopril, spironolactone, and naproxen; stop any K⁺-containing fluids or supplements; continuous cardiac monitoring; strict I&O with a bladder scan; serial K⁺ and glucose checks.
Step 5 — Take Action
Sequencing question: the orders arrive together — calcium gluconate, insulin + D50, albuterol neb, fluid bolus, binder. The pharmacy tube delivers the insulin first. A colleague reaches for it. What’s the right order, and what monitoring does the insulin commit you to?
▸Reveal answer
Calcium first, even though it arrived second. The membrane is the emergency — peaked T waves mean the heart is one rhythm strip from trouble, and calcium is the only drug on the list that protects it now. Then the shifters (insulin/D50, albuterol), then the removers (fluids, binder), in quick succession.
The insulin commitment: IV insulin in a patient who isn’t hyperglycemic means scheduled glucose checks for several hours — hypoglycemia is the most common complication of hyperkalemia treatment, and it often lands after everyone has relaxed. Set the timer when you push the dose.
And re-verify while treating: repeat K⁺ (rules out a hemolyzed first sample and tracks response), continuous monitoring with the 12-lead compared against the strip, and watch the urine — the bolus’s report card is the Foley bag.
Step 6 — Evaluate Outcomes
1700: K⁺ 5.4 · T waves normalized · HR 72 · urine 60 mL/hr after two liters · creatinine pending · glucose 84 after the second check. The hospitalist plans admission. Which findings show success, what’s temporary, and what does discharge teaching owe this man?
▸Reveal answer
Improving: the EKG normalized (the goal that mattered), potassium trending down, and — most importantly — urine flowing, which means the prerenal insult is reversing and his kidneys can finish the job the medications started.
Temporary and worth saying out loud at handoff: the insulin/albuterol shift wears off in hours — potassium can rebound, so serial levels continue; glucose checks continue; the creatinine needs days to declare whether this was pure prerenal or earned some tubular injury.
The teaching that prevents the readmission: sick-day rules — when vomiting/diarrhea hits, hold the ACE inhibitor, spironolactone, and NSAIDs and call; no more around-the-clock naproxen with his kidneys and heart failure (gout needs a safer plan); which meds restart, when, and who decides; and the salt-substitute warning (most are potassium chloride). His pharmacist and PCP both need this story.
Debrief — The Pattern to Keep
- ✦K⁺ with EKG changes = calcium gluconate first — it protects the heart and does nothing to the level; that's the point.
- ✦Protect → shift → remove: calcium, then insulin/D50 + albuterol, then fluids/binders/dialysis — shifts are temporary, watch for rebound.
- ✦ACE inhibitor + potassium-sparing diuretic + NSAID on a dehydrated patient = the triple whammy that builds prerenal AKI.
- ✦Insulin for hyperkalemia commits you to hours of glucose checks — hypoglycemia is the treatment's favorite complication.
- ✦Working kidneys are the best potassium removal — treat the volume, hold the offenders, and teach the sick-day rules.