Potassium

Last updated 24/03/18

Definition

• Intra and extracellular electroyte essential for normal cell function

Features

• Predominantly intracellular cation (K+)
• Plays essential role in nerve conduction
• Also influenced by acid-base balance
• Often given hesitantly but is an essential nutrient
• Excreted by kidneys

Mechanism

• Replenshes endogenous stores

Indications

• Hypokalaemia
• Metabolic alkalosis from vomiting: potassium chloride
• Metabolic acidosis from diarrhoea or RTA: potassium bicarbonate
• Advanced Life Support (ALS): 5mmol IV bolus
• Plus Magnesium sulphate 2g IV
• Intravenous fluid daily maintenance
• 0.7-0.9 mmol/kg/day

Dose

• PO or IV
• Every 10mol KCl increases serum K+ by around 0.1mmol
• PO
• Tablets (Potassium chloride): 600mg Slow Release = 8mmol (Slow-K, Span-K, Duro-K)
• Effervescent Tablets (Potassium chloride + Potassium Bicarbonate): 14mmol (Chlorvescent)
• Dissolved in 120ml per tablet
• Take with or immediately after food
• 1-2 (of either) PO BD to TDS
• IV
• Fluids
• With Normal Saline 0.9%
• 1000ml: KCl 10mmol, 20mmol, 30mmol, 40mmol
• 100ml: KCl 10mmol, 40mmol
• 10ml: KCL 10mmol
• Should not be given at >10mmol/hr

Side Effects/Precuations/Contraindications

• Side Effects
• Nausea, vomiting, diarrhoea, abdominal cramps
• Hyperkalaemia
• Cardiac arrest
• Pain on injection
• Precautions
• Chronic Kidney Disease (CKD): high risk of hyperkalaemia
• Spironolactone: risk of hyperkalaemia
• Contraindications
• Hyperkalaemia

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References

1. AMH: Oral Electrolytes. January 2018.
2. MIMS Online: Span-K. March 2018.