[9] Hyperkalaemia Flashcards
What is classified as hyperkalaemia?
A serum potassium of greater than 5.5mmol/L
When is hyperkalaemia usually asymptomatic?
At relatively low levels
Why is hyperkalaemia a very important condition to identify and treat early?
Due to cardiac and other complications that can arise
What are the causes of hyperkalaemia?
- Oliguric renal failure
- Potassium sparing diuretics
- Rhabdomyolysis
- Metabolic acidosis
- Excess potassium therapy
- Addison’s disease
- Massive blood transfusion
- Burns
- Drugs
- Artefactual result
Give an example of a drug that can cause hyperkalaemia?
ACE inhibitors
What should be done if a patient is found on testing to be hyperkalaemic but they do not display any signs or symptoms of hyperkalaemia?
The test should be repeated urgently, as it may be artefactual
What can cause an artefactual hyperkalaemia result?
- Haemolysis
- Contamination with potassium EDTA in FBC bottles
- Thrombocythaemia
- Delayed analysis
What can cause haemolysis leading to an artefactual hyperkalaemia result?
- Difficult venepuncture
- Patient clenching their fist
How can thrombocythaemia cause an artefactual hyperkalaemia result?
Because potassium leaks out from platelets during clotting
How can delayed analysis lead to an artefactual hyperkalaemia result?
Potassium leaks out of RBCs
Below what serum potassium concentration are symptoms rare in hyperkalamia?
Less than 7.0mmol/L
What are the signs and symptoms of hyperkalaemia?
- Fast, irregular pulse
- Chest pain
- Weakness
- Palpitations
- Light-headedness
- Paresthesia
When should clinical assessment in hyperkalaemia take place?
Needs to be timely, and is often performed simultaneously with treatment
What is involved in the clinical assessment of hyperkalaemia?
- Urine output
- Review of potassium intake
- Review of drugs
- Review history for possible causes of renal disease or major tissue destruction
- Fluid status
- Review recent biochemistry results, in particular renal function and potassium levels
What sources of potassium intake need to be reviewed in hyperkalaemia?
- IV fluids
- Potassium supplements
- Diet
What drugs should be reviewed in hyperkalaemia?
- ACE inhibitors
- Angiotensin II receptor blockers
- Potassium sparing diuretics
What should be involved in a fluid status assessment?
Look for signs of dehydration or fluid overload
Describe the importance of ECG in hyperkalaemia
The ECG is vital in the assessment of hyperkalaemia, with the findings progressing with increasing serum potassium levels
Describe the relationship between serum potassium concentration and ECG
While ECG findings can generally be correlated to serum potassium concentration, potentially life-threatening arrhythmias can occur without warning at almost any level of hyperkalaemia
What is considered to be mild hyperkalaemia?
5.5-6.5mmol/L
What are the ECG findings in mild hyperkalaemia?
- Tall ‘tented’ T waves seen across the precordial leads
- Prolonged PR segment
What is considered to be moderate hyperkalaemia?
6.5-7.5mmol/L
What are the ECG findings in moderate hyperkalaemia?
- Decreased or ‘flattened’ P wave
- Prolonged QRS complex
What is considered to be severe hyperkalaemia?
>7.5mmol/L
