Reasoning GP · Algorithm · 1-page summary
Hyperkalaemia in adults
For: adults with a raised potassium result, in hours or OOH. Not for: children; DKA (hospital protocol); hospital IV treatment (full algorithm, step 6).
Core rule: K⁺ ≥6.5 mmol/L, or any ECG change potentially due to hyperkalaemia, is an emergency however well the patient seems — transfer, do not repeat first. Confirm in parallel, never instead. A normal ECG does not exclude severe hyperkalaemia.
0Stop — emergency admission now — 999 or immediate discussion with the acute team
- K⁺ ≥6.5 mmol/L on any sample, or any ECG change potentially due to hyperkalaemia (peaked T, flat or absent P, broad QRS, bradycardia, sine wave) → 999
- Symptoms at any level: palpitations, syncope, chest pain, new arrhythmia, muscle weakness, flaccid paralysis, paraesthesiae → 999
- AKI (oliguria, new confusion, volume depletion, rapidly rising creatinine), missed dialysis, rhabdomyolysis, crush injury, tumour lysis, massive haemolysis, rapidly rising K⁺, suspected digoxin toxicity → 999
- While waiting: ECG only if it does not delay transfer; repeat K⁺ only in parallel. No IV calcium in routine primary care. Withhold ACE inhibitor, ARB, MRA, amiloride, K⁺ supplements, salt substitutes, trimethoprim, NSAIDs. Hand over K⁺ trend, eGFR, drugs withheld; say "query rhabdomyolysis / tumour lysis".
1Triage by level — ≥6.5 is block 0
| K⁺ mmol/L | Action |
|---|---|
| 6.0–6.4 | ECG today. Acutely unwell or AKI → Same-day hospital. Well → discuss with the renal/medical team, hold contributors, repeat within 1 day; still ≥6.0 → admit. |
| 5.5–5.9 | Well, no AKI → Review ideally same working day; repeat ≤3 days. ECG if cardiac disease, rapid rise, significant renal impairment or symptoms; no ECG or follow-up → same-day. |
| 5.1–5.4 | Not hyperkalaemia. On RAAS drugs: repeat, remove contributors, recheck 1–4 weeks. |
2Screen — one row is enough
- Spurious? Haemolysis, fist clenching, delay, high platelets or white cells → ask the lab. Repeat first only if <6.5, well, no AKI, normal ECG.
- AKI: creatinine up on previous, oliguria, sepsis, obstruction, recent NSAID or contrast → Emergency transfer
- Adrenal crisis: high K⁺ with low sodium, postural hypotension, pigmentation, steroids stopped. Hypotensive, vomiting or unwell → 999; IM hydrocortisone if trained and authorised, without delay. Else → Same-day endocrine or renal advice.
- Rise after starting or up-titrating RAAS drug or MRA → Same-day dose review; advice before stopping an MRA.
- Unexplained renal impairment with systemic features (weight loss, bone pain, anaemia, hypercalcaemia) → Myeloma screen (NG12; very urgent if hypercalcaemia or leukopenia); refer urgently if abnormal.
3Assess — once blocks 0–2 are answered
☐ ECG at ≥6.0; compare with previous (broad QRS: bundle branch block, pacing?) ☐ Volume, postural BP, pulse, bladder, power, glucose ☐ U&E on a clean sample processed <30 min; bicarbonate, glucose, FBC; full drug list
Not in primary care: IV calcium, a binder as emergency treatment, routine aldosterone and renin.
4Classify the cause — once urgency is settled
- Drugs — commonest: ACE inhibitor, ARB, MRA, amiloride, trimethoprim, NSAIDs, heparin, ciclosporin, tacrolimus → block 5.
- Kidney — AKI, CKD 4–5, obstruction: ask what changed.
- Endocrine or tubular — low sodium: Addison's; low bicarbonate, normal anion gap in diabetic CKD: type 4 RTA → renal assessment.
- Shift or load — acidosis, beta-blockers, digoxin toxicity; salt substitutes. Hyperglycaemic and unwell: DKA first.
- Uncertain or recurrent — say so; block 6 route; name the reviewer and timeframe.
5Treat today — mild, well, no AKI
- Stop K⁺ supplements, salt substitutes (LoSalt); stop or switch trimethoprim, NSAIDs (including OTC ibuprofen), heparin where possible.
- ACE inhibitor, ARB, MRA: remove reversible contributors first, then consider dose change or specialist advice. Heart failure or albuminuric CKD → plan reintroduction. Any RAAS dose change → K⁺ and eGFR at 1–2 weeks.
- Diet: individualised substitution; do not reflexively restrict milk, pulses, nuts, vegetables. Never diet alone at ≥6.0. Correct dehydration.
- Recheck U&E within 3 days, named reviewer, written escalation thresholds. Personalised written sick-day plan with restart advice. Doses: NICE/SPC, BNF, local formulary.
6Refer routinely
- Persistent despite removing contributors, declining eGFR or proteinuria → nephrology.
- Limiting a needed RAAS drug or MRA → renal or cardiology advice on dose and a binder (CKD 3b–5 or heart failure, not on dialysis; confirmed K⁺ ≥5.5 for sodium zirconium cyclosilicate, ≥6.0 for patiromer); SZC can be started in primary care (TA1148, UKKA 2026). Never a substitute for emergency transfer.
- Stable suspected Addison's → endocrinology with 9 am cortisol. Type 4 RTA → nephrology; no fludrocortisone in primary care.
7Never reassure by — never repeat ≥6.5 instead of transferring; never leave a critical result in an inbox overnight
- The patient feeling well — K⁺ of 7 often feels normal until the arrhythmia.
- A normal ECG.
- A normal K⁺ on a haemolysed repeat after a genuine high result.
- "Probably haemolysis" without asking the lab, or at ≥6.5.
- "Chronic and stable" without comparing the trend.
- "Diet" with normal eGFR and no drugs, or a low sodium or bicarbonate beside it.
8Safety-net — say it, then document it
999 “Call 999 if you collapse or black out.” Same day: “Contact us or 111 today for palpitations, feeling faint, new muscle weakness or numbness, being unable to keep fluids down, or passing much less urine. Come for the repeat even if you feel well. No salt substitutes; no ibuprofen without checking.”
Remote or OOH: ≥6.0 cannot be managed by telephone — same-day ECG and face-to-face; no ECG today or cannot attend → emergency assessment. Name who acts on a critical result out of hours.
✓Safe to manage in primary care only if — all five, documented
K⁺ 5.5–5.9, well, no AKI; no block 0–2 row
ECG normal where indicated; sample quality checked
Sodium, bicarbonate, glucose reviewed; cause acted on
Repeat ≤3 days booked; named reviewer; written thresholds
Safety-net and sick-day plan given
Summary of the full Reasoning GP hyperkalaemia algorithm, which holds the detail, hospital treatment reference and evidence. Sources: UK Kidney Association (2023); NICE NG203, NG148, NG106, NG136, NG12, TA1148, TA623; SPS; MHRA; local shared care. Clinical reference — follow local acute-transfer, renal and prescribing policies and check doses: NICE/SPC, BNF.