Hyperkalaemia
UK Kidney Association Clinical Practice Guidelines Treatment of Acute Hyperkalaemia in Adults. Published: Oct 2023.
Background Information
Definition
Hyperkalaemia is defined as serum potassium ≥5.5 mmol/L
Classification of severity:
| Severity | Potassium concentration (mmol/L) |
|---|---|
| Mild | 5.5 – 5.9 |
| Moderate | 6.0 – 6.4 |
| Severe | ≥6.5 |
Aetiology
Given the extensive list of potential causes, memorising all of them is neither practical nor necessary. Prioritising the major causes and being able to recognise them in clinical practice is far more valuable.
Drug Causes
Drugs commonly implicated in hyperkalaemia
- RAAS inhibitor
- ACE inhibitor
- ARB
- Mineralocorticoid receptor antagonists (i.e. aldosterone receptor antagonist like spironolactone and eplerenone)
- Potassium-sparing diuretics (i.e., MRAs, amiloride/triamterene)
- NSAIDs
- Non-selective beta blockers
- Trimethoprim / Co-trimoxazole
- Potassium supplements
Other Causes
- Acute and chronic kidney disease
- Hyporeninemic hypoaldosteronism (Type IV renal tubular acidosis)
- Adrenal insufficiency
- Pathological cell lysis (with release of intracellular K+ into the blood)
- Rhabdomyolysis
- Tumour lysis syndrome
- Haemolysis
Risk Factors
- Dialysis dependency
- Heart failure
- Diabetes
- Liver disease
ECG Changes
Progressive ECG changes seen in hyperkalaemia:
| Associated potassium levels | ECG changes |
|---|---|
| ≥6.0 mmol/L |
|
| ≥6.5 mmol/L |
|
| ≥7.0 mmol/L |
|
Pseudohyperkalaemia
Definition:
- Falsely elevated potassium levels
- Defined by serum potassium being >0.4 mmol/L than plasma potassium
If pseudohyperkalaemia is suspected:
- Send paired blood samples in 1) a clotted tube (serum) and 2) a lithium heparin tube (plasma)
Causes: mainly related to excess haemolysis during or after venipuncture
- Iatrogenic
- Prolonged transit time to laboratory / poor storage conditions – most common
- Prolonged tourniquet use
- Difficult/traumatic venipuncture
- Vigorous fist clenching
- ↑ Platelet count / Erythrocytosis
Pseudohyperkalemia should be suspected when a measured elevation in serum or plasma potassium is discordant with the clinical context, especially in the absence of symptoms, electrocardiographic changes, or risk factors for true hyperkalemia.
Management
Primary Care Management
Refer to hospital immediately if severe hyperkalaemia (≥6.5 mmol/L)
- Mild/moderate hyperkalaemia (detected in community): can generally be managed without the need for hospital admission, unless the patient is acutely unwell or has an AKI.
- Management includes:
- Medication review (see above for drugs implicated in hyperkalaemia)
- Low potassium diet
- Consider diuretic (loop or thiazide) if patient is non-oliguric and non-hypovolaemic
- Monitor serum potassium
- Management includes:
Potassium binders (calcium resonium / sodium zirconium cyclosilicate / patiromer calcium) can be considered in:
- Moderate hyperkalaemia, and
- Patient with CKD 3b-5 (not on dialysis) or heart failure
Note that potassium binders should only be initiated in secondary care
Secondary Care Management
Summary Table
This table summarises the 3 main steps in the management of hyperkalaemia, in order of urgency:
| Step | Aim and description | Recommended treatment |
|---|---|---|
| 1 (cardiac protection) | Stabilises the cardiac membrane by increasing the action potential threshold to reduce the risk of arrhythmia
Note that this step does NOT lower potassium level, it mainly buys time until potassium can be shifted or removed |
|
| 2 (potassium shifting) | Temporarily shifts potassium from extracellular to intracellular compartment to reduce potassium concentration |
Do not routinely give IV sodium bicarbonate (it has limited role in metabolic acidosis) |
| 3 (potassium removal) | Removes potassium from the body
Definitive correction of hyperkalaemia |
Potassium binders:
Other options:
|
Emergency Management Algorithm
This section applies to BOTH moderate and severe hyperkalaemia (≥6.0 mmol/L)
- If there is severe hyperkalaemia (≥6.5 mmol/L), senior input should be sought early
- Mild hyperkalaemia (5.5-5.9 mmol/L) does not require any specific treatment
If the patient develops cardiac arrest → ALS algorithm takes priority but treat the underlying hyperkalaemia in a similar fashion as below.
Step 1
Perform an ECG urgently
- If there are any ECG changes (even if isolated tall tented T waves) → IV calcium gluconate 10% (30 mL over 10 min) or IV calcium chloride 10% (10 mL over 5 min)
- Consider a further dose if ECG changes persist after 5 min
Step 2
This step applies to patients with moderate and severe hyperkalaemia (≥6.0 mmol/L)
- Give insulin-glucose IV infusion (10 units of soluble insulin in 25g of glucose over 15-30 min), and
- Consider
- Nebulised salbutamol (10-20 mg)
- Potassium binders (sodium zirconium cyclosilicate / Patiromer calcium)
- For refractory hyperkalaemia: seek expert help and consider haemodialysis
Monitor serum potassium and blood glucose throughout