Hyperkalaemia Flashcards
What is Hyperkalaemia?
Hyperkalaemia refers to a raised serum potassium level, which can lead to cardiac arrhythmias, such as ventricular fibrillation, and can potentially result in cardiac arrest.
What are the normal and different levels of serum potassium in Hyperkalaemia?
Normal: 3.5 – 5.3 mmol/L
Mild Hyperkalaemia: 5.4 – 6 mmol/L
Moderate Hyperkalaemia: 6 – 6.5 mmol/L
Severe Hyperkalaemia: Over 6.5 mmol/L
What conditions can cause Hyperkalaemia?
Conditions include:
* Acute kidney injury
* Chronic kidney disease (stage 4 or 5)
* Rhabdomyolysis
* Adrenal insufficiency
* Tumour lysis syndrome
What medications can cause Hyperkalaemia?
Medications include:
* Aldosterone antagonists (e.g., spironolactone, eplerenone)
* ACE inhibitors (e.g., ramipril)
* Angiotensin II receptor blockers (e.g., candesartan)
* NSAIDs (e.g., naproxen)
How can haemolysis affect potassium levels?
Haemolysis (rupture of blood cells) during sampling can lead to falsely elevated potassium levels, known as pseudohyperkalaemia. The lab may note haemolysis and recommend a repeat sample.
What ECG changes are associated with Hyperkalaemia?
ECG changes include:
* Tall peaked T-waves
* Flattening or absence of P waves
* Prolonged PR interval
* Broad QRS complexes
What is the management approach for Hyperkalaemia with a serum potassium below 6.5 mmol/L and no ECG changes?
Management focuses on treating the underlying cause (e.g., addressing acute kidney injury and stopping medications like spironolactone or ACE inhibitors).
When should urgent treatment be initiated for Hyperkalaemia?
Urgent treatment is required if:
* There are ECG changes
* The serum potassium is above 6.5 mmol/L
What is the mainstay of treatment for Hyperkalaemia?
The main treatment is an insulin and dextrose infusion and IV calcium gluconate:
* Insulin drives potassium into cells
* Dextrose prevents hypoglycaemia while on insulin
* Calcium gluconate stabilises cardiac muscle cells and reduces arrhythmia risk
What other options are available for lowering serum potassium in Hyperkalaemia?
Other options include:
* Nebulised salbutamol: Temporarily drives potassium into cells
* Oral calcium resonium: Reduces potassium absorption in the GI tract (causes constipation)
* Sodium bicarbonate: Corrects acidosis and drives potassium into cells (used under renal advice)
* Haemodialysis: May be required in severe or persistent cases
