Potassium, serum

Clinical background:

Diagnosis and monitoring of hypo and hyperkalaemia

Specimen container paediatric:

Serum (SST or plain tube)

Specimen container adult:

Serum (SST or plain tube)

Minimum volume paediatric:

0.5 mL blood

Minimum volume adult:

1 mL blood

Sample stability:

• Unseparated:
  • Within 10 hours of collection
• Separated:
  • 14 days at 15-25^oC
  • 14 days at 2-8^oC
  • 1 year at -20^oC

Reference ranges:

• up to 4 weeks: 3.4 – 6.0 mmol/L
• 4w – 1y: 3.5 – 5.7 mmol/L
• 1y – 16y: 3.5 – 5.0 mmol/L
• 16y and over: 3.5 – 5.3 mmol/L

Factors affecting result:

Spurious hyperkalaemia may be caused by pre analytical factors:
Sample haemolysis, delay in sample centrifugation, sample contamination with K-EDTA or K-Oxalate. Haematological conditions such as thrombocytosis and leukocytosis may cause spurious hyperkaleamia due to potassium leakage during clotting process.

Other info:

Lithium heparin plasma sample also acceptable