Hyperkalaemia: Primary Care (Guidelines)

TAM (Treatments and Medicines) NHS Highland
NHS Highland

Audience

  • All NHS Highland
  • Primary Care only
  • Adults only

Causes

The causes are often multifactorial and can include:

  • Factitious
    • Delay in centrifuging of more than 8 hours (i.e. ‘old sample’)
    • Pre-mature centrifuging. Samples should remain upright for 30 minutes after taking to allow blood to clot.
    • Contamination with EDTA (FBC) in tube
    • Refrigeration if not centrifuged / spun
    • Haemolysis during venipuncture or excess cuff time
    • High platelets
    • High white cells
  • Renal
    • Acute kidney injury or chronic kidney disease
    • Interstitial nephritis or tubular disease
    • Lack of aldosterone, eg, most commonly hyporeninaemic hypo-aldosteronism in diabetics and the elderly (type 4 renal tubular acidosis) but also Addison’s disease, congenital adrenal hyperplasia
  • Drugs
    • ACE inhibitors, ARBs, NSAIDs, aldosterone antagonists, such as spironolactone or eperenone
    • Trimethoprim and co-trimoxazole.
    • Patients on these medications should be given information on ‘sick day rules’ and advice on withholding during acute illness (due to risks of AKI and hyperkalaemia).
  • Advanced chronic cardiac failure
  • Redistribution
    • Acidosis
    • Diabetic ketoacidosis
    • Drugs: Beta blockers, digoxin
  • Excess potassium
    • Excess potassium in the diet/ potassium supplements / potassium-containing laxatives (such as Movicol/Laxido and Fybogel).
    • Cell tissue breakdown (eg, rhabdomyolysis, haemolysis, tumour lysis, transfusion)
If aetiology is unclear, please consider discussion with the duty biochemist as there are possible further investigations that may be required.

Assess severity and urgency

Severity of hyperkalaemia

 Clinically well (no AKI) Unexpected result Clinically unwell or AKI


MILD:

REVIEW
  • K+ 5.5 to 5.9mmol/L
Repeat within 14 days Repeat within 3 days Consider if hospital referral is indicated
Guided by clinical circumstance & risk of further deterioration
  • Review medicines & diet for causes
  • Patients with heart failure on aldosterone antagonists: reduce dose by half and monitor U&Es


MODERATE:

URGENT REVIEW
  • K+ 6.0 to 6.4mmmol/L
Repeat within 1 working day
Routine blood tests unavailable at weekends & OOH from community		 Repeat within 24 hours
Via Secondary Care, if needed		 Refer to hospital
  • Review medicines & diet for causes: Stop any medicines that may elevate K
  • Patients with heart failure on aldosterone antagonists: refer to hospital
  • All those with K ≥6.0mmol/L should have an ECG taken to look for hyperkalaemia-related abnormalities.
  • Abnormal ECG changes in hyperkalaemia may include bradycardia, P waves absent or PR prolongation, peaked T waves, widened QRS, VT or VF.

 

SEVERE:

URGENT REFERAL
  • K+ ≥6.5 mmol/L
  • OR K+ ≥6.0 mmol/L PLUS Stage 1 AKI (i.e. fall in eGFR but eGFR still >90)
  • OR K+ ≥5.5 mmol/L PLUS ECG changes
  • OR acute increase >0.5mmmol/L over 6 to 12 hours


URGENT REFERRAL via on-call medical receiving for immediate assessment and treatment
There is a risk of cardiotoxicity and sudden cardiac death with severe hyperkalaemia or those with ECG changes.
NOTE: Renal patients may be more tolerant of high potassium levels but if there is uncertainty about the need for admission with this group of patients it is best to discuss with the on-call renal team.

Assess trend

  • Pseudo-hyperkalaemia is a common cause when there is an isolated rise in K or unexpected potassium result, especially where there are no ECG changes, symptoms or history/evidence of kidney disease.
  • Consider discussing with the lab if uncertainty exists.
  • An urgent repeat should be arranged with secondary care when K ≥6.0mmol/L.
  • If there is a possibility of fragile blood cells (eg, in CLL, thrombocytosis, leucocytosis, vasculitis) send a whole blood potassium in lithium heparin tube putting ‘for on-call Consultant Biochemist’ on ICE request, if using ICE.
  • Check previous K results but if there is a rapid rise (K >0.5mmol/L over 6 to 12 hrs) an urgent referral to secondary care should be arranged as this is associated more strongly with conduction abnormalities.

Assess clinical situation

  • Assess for any symptoms, which include: lethargy, nausea, muscle weakness or paraesthesia.
  • Do an ECG when K >6.0mmol/L.
  • Look for any possible causes of hyperkalaemia, such as those listed above.
  • Review diet for high potassium intake: banana, nuts, dried fruits, avocado.
  • Review medications.
    • Those listed above, and potassium-containing laxatives, are the commonest cause of hyperkalaemia.
    • The most common course of action is to withhold the likely offending drug or laxative.

Investigations

Review recent results or organise appropriate tests:

  • Look for evidence renal impairment (check U&E)
  • Look for evidence of acidosis (venous bicarbonate)
  • Look for possible diabetes (check fasting glucose)
  • If relevant, consider DKA (check urine ketones)
  • Consider Addison’s if hyponatraemia and hyperkalaemia (check 9am Cortisol)
  • Look for evidence of tissue damage (check CK, LDH)
  • Look for underlying condition that may increase cell fragility (check FBC)

Self management information

Editorial Information

Last reviewed: 27/02/2025

Author(s): Primary Care.

Version: 1

Approved By: APPROVED ADTC of TAM Subgroup

Reviewer name(s): Dr S McCabe.

Document Id: TAM674