Hyperkalemia

Written by – Dr Andrew Lam 

Hyperkalemia

Causes of Hyperkalemia

Increased Intake

• Excessive potassium dietary supplements
• Excessive iatrogenic IV supplementation

Decreased Excretion

• Acute or chronic renal failure/impairment
• Hypoaldosteronism
• Drugs (potassium sparing diuretics, ACEI’s, tacrolimus, cyclosporin)

Intercompartmental Shift

• Pseudohyperkalemia (i.e. haemolysis from blood drawing) 
• Acidosis
• Insulin deficiency
• Rapid Cell Lysis (i.e. rhabdomyolysis, cytotoxic therapy) 
• Beta blockers

ECG changes in Hyperkalemia

Mild Changes (K > 5.5mmol/L)

• Peaked T Waves

Moderate Changes (K > 6mmol/L)

• P wave widening/flattening, followed by the disappearance
• PR prolongation

Severe Changes (K > 7mmol/L)

• Widened QRS interval
• Sine-Wave Rhythm
• Ultimately results in ventricular fibrillation or asystole

Management of Hyperkalemia

Hyperkalemic Emergency if any of the 3 criteria are met: 

1. Clinical manifestations or ECG changes suggestive of hyperkalemia
2. Serum potassium > 6.5s
3. Serum potassium > 5.5 with renal impairment or ongoing tissue breakdown

In Hyperkalemic Emergency, immediate management requires:

• Calcium Gluconate or Calcium Chloride (stabilises cardiac membrane) 
• Insulin and glucose 
• Bicarbonate (in patients who are concurrently acidotic)

This is given concurrently with therapy which removes potassium from the body:

• Haemodialysis in patients with renal failure
• Loop diuretics (i.e. frusemide)
• Cation exchanger (i.e. resonium) 

References: 

Life in the Fast Lane. (2021). Hyperkalemia • LITFL • CCC. March 22, 2021, from, https://litfl.com/hyperkalaemia-ecg-library/

Mount, D.B., (2020). Causes and evaluation of hyperkalaemia in adults. UpToDate. Retrieved March 22, 2021, from https://www.uptodate.com.acs.hcn.com.au/contents/causes-and-evaluation-of-hyperkalemia-in-adults

Mount, D.B., (2020). Treatment and prevention of hyperkalaemia in adults. UpToDate. Retrieved March 22, 2021, from https://www.uptodate.com.acs.hcn.com.au/contents/treatment-and-prevention-of-hyperkalemia-in-adults