Hypokalemia detected (adults)
Serum K+ below 3.5 mmol/L. Mild 3.0-3.4, moderate 2.5-2.9, severe below 2.5 mmol/L.
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Internal MedicineEmergency
Acute Hypokalemia Management - Hospitalist
Acute Hypokalemia Management - Hospitalist: Hypokalemia detected (adults) → Adults only. DKA or HHS with K+ below 3.5 mmol/L: K+ before insulin → Assess...
Pathway Overview
11 steps
Algorithm Steps
11 total
01Start 02Warning Adults only. DKA or HHS with K+ below 3.5 mmol/L: K+ before insulin
Children: use a paediatric weight-based protocol.
- DKA or HHS with K+ below 3.5 mmol/L: give K+ at 10 mmol/h first
- Start insulin only when K+ is above 3.5 mmol/L
- Then keep K+ at 4-5 mmol/L; check K+ 2 h after insulin starts, then every 4 h
03Action Assess severity
Treat as severe if K+ is below 2.5 mmol/L or there is weakness, paralysis, arrhythmia or ECG change.
- Check Mg, creatinine, glucose and blood gas
- Ongoing losses (vomiting, diarrhoea, diuretics) raise the dose needed
- On digoxin: check the digoxin level; low K+ raises the risk of digoxin toxicity
- Metabolic acidosis (diarrhoea, renal tubular acidosis): give K+ before or with any bicarbonate; bicarbonate lowers K+ further
04Action 12-lead ECG
Continuous ECG monitoring if K+ below 2.5 mmol/L, symptoms, arrhythmia or ECG changes.
- Flat or inverted T waves, prominent U waves, ST depression
- Long QT (QU) interval
- Ectopics, AF, VT or VF
05Warning Before replacing K+: check Mg, kidneys, drugs and shift causes
Do not delay IV K+ in severe hypokalemia while you wait for results.
- Low Mg with severe or symptomatic low K+: magnesium sulfate 8 mmol (4 mL of 2 mmol/mL ampoule) in 10 mL sodium chloride 0.9% IV over 20 min, then K+, then continue Mg. Mild or moderate: replace Mg per local protocol. K+ stays low until Mg is replaced
- Kidney impairment, oliguria, ACE inhibitor, ARB, MRA, amiloride or trimethoprim: smaller K+ and Mg doses, closer K+ and Mg checks; dialysis or severe kidney impairment: contact the renal team
- Shift causes (thyrotoxic or familial periodic paralysis): small doses, rebound high K+ risk
06Decision Needs IV potassium?
Yes if K+ below 2.5 mmol/L, symptoms, arrhythmia or ECG changes, or cannot take oral K+.
- If Yes
07Action IV potassium: severe, symptomatic or no oral route
Adults. Premixed bags only, on a rate-limiting pump. Never give IV push. Heart failure or fluid overload: watch the fluid volume (1 L per 40 mmol); a stronger solution needs a central line.
- Typical: 40 mmol KCl in 1 L sodium chloride 0.9% at 10 mmol/h; check K+ before each further bag
- Peripheral line: max 10 mmol/h and max 40 mmol/L (only exception: 10 mmol in 100 mL sodium chloride 0.29% isotonic premix)
- Faster than 10 mmol/h or stronger than 40 mmol/L: central line, cardiac-monitored area, continuous ECG. Faster than 20 mmol/h: HDU or ICU only, with consultant agreement
- Prefer sodium chloride-based fluid; glucose fluids can lower K+ further
- Change to oral K+ when able
08Action Monitor response
- Continuous ECG if K+ below 2.5 mmol/L, symptoms, arrhythmia, ECG changes or IV rate above 10 mmol/h; check K+ before each further IV bag and at the end of IV replacement
- Mild or moderate on oral K+: K+ daily
- K+ not rising: check Mg and look for ongoing losses
- Kidney impairment: watch for overshoot to high K+
09Action Find and treat the cause
Urine K+ and acid-base status help separate kidney losses from other causes. Tachycardia or periodic paralysis: check TSH.
- Gut losses: vomiting, NG suction, diarrhoea, laxatives
- Kidney losses: thiazide or loop diuretics, hyperaldosteronism, renal tubular acidosis, low Mg
- Shift into cells: insulin, beta-agonists, alkalosis, refeeding, thyrotoxicosis
- Ongoing diuretic loss: a K+-sparing diuretic only with normal kidney function and K+ checks
10Outcome K+ corrected
K+ back in the normal range (3.5-5.0 mmol/L), Mg replaced, cause treated, follow-up K+ check arranged.
If No11Action Oral potassium: mild or moderate, no symptoms
Adults. Oral route is preferred when possible.
- Potassium chloride 40-100 mmol/day orally, in divided doses
- Slow-release KCl 600 mg tablet = 8 mmol; swallow whole with food and water. Swallowing problems or slow gut transit: use a liquid form, not tablets
- Recheck K+ daily and adjust
- The deficit is large (about 200-400 mmol per 1 mmol/L fall), so each dose raises K+ only a little
- Path rejoins step 08Shared downstream outcome
Guideline Source
Kardalas E, et al. Hypokalemia: a clinical update. Endocr Connect 2018;7(4):R135-R146 (with WA Health Intravenous Potassium Standard, December 2025, for IV administration)
Clinical Safety Information
Clinical Decision Support — Not a Substitute for Clinical Judgment
Individual patient factors may require deviation from these recommendations.
Known Limitations
- Adults only: children need a paediatric weight-based protocol
- IV potassium limits follow Australian state policy (WA Health 2025); follow your hospital policy
- DKA and HHS: only the potassium step is given; use the full DKA protocol
- Cause-specific treatment (for example hyperaldosteronism) needs specialist input
Contraindicated Populations
children (use a paediatric weight-based protocol)
Applicable Regions
AUUSEU
AU: IV potassium rules follow the ACSQHC high-risk medicine alert and state policy (for example WA Health 2025): premixed bags; peripheral max 10 mmol/h and 40 mmol/L except the isotonic 10 mmol in 100 mL premix; above 20 mmol/h only in HDU or ICU.
US: K+ in mEq/L equals mmol/L. Local IV potassium policies differ; follow your hospital policy.
Version 2Next review: 2027-09-30
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Frequently Asked Questions
What is the Acute Hypokalemia Management - Hospitalist?
The Acute Hypokalemia Management - Hospitalist is a emergency clinical algorithm for Internal Medicine. It provides a structured decision tree to guide clinical decision-making, based on Kardalas E, et al. Hypokalemia: a clinical update. Endocr Connect 2018;7(4):R135-R146 (with WA Health Intravenous Potassium Standard, December 2025, for IV administration).
What guideline is the Acute Hypokalemia Management - Hospitalist based on?
This algorithm is based on Kardalas E, et al. Hypokalemia: a clinical update. Endocr Connect 2018;7(4):R135-R146 (with WA Health Intravenous Potassium Standard, December 2025, for IV administration) (DOI: 10.1530/EC-18-0109).
What are the limitations of the Acute Hypokalemia Management - Hospitalist?
Known limitations include: Adults only: children need a paediatric weight-based protocol; IV potassium limits follow Australian state policy (WA Health 2025); follow your hospital policy; DKA and HHS: only the potassium step is given; use the full DKA protocol; Cause-specific treatment (for example hyperaldosteronism) needs specialist input. Individual patient factors may require deviation from these recommendations.
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