Pathology tests database

Sample and container requirements

Serum Lithium Heparin Plasma (paediatrics only)

Minimum volume required

100 µL serum/plasma

Special requirements

None

Patient preparation

None

Sample viability

Turnaround time

This assay is run throughout the day and night. The in-lab turnaround time is normally less than 24 hours. The test can be ordered as an urgent request.

Reference range

Neonates (<4 weeks): 3.4 – 6.0 mmol/L Infant (<1 year): 3.5 – 5.7 mmol/L 1 – 16 years: 3.5 – 5.0 mmol/L Adults: 3.5 – 5.3 mmol/L (Source: Pathology Harmony Recommendations)

Clinical guidance

Potassium forms part of the standard U&E (urea and electrolyte) panel in blood. Please refer to LabTestsOnlineUK to learn more about potassium. https://labtestsonline.org.uk/tests/potassium-test

Notes

Potassium can be artificially elevated by delayed centrifugation of samples. Interpret a raised potassium with caution if there has been a >8 hr delay between the sample being taken and received by the laboratory. Exposure of whole blood to extremes of temperature affects potassium concetration. High temperatures lead to falsely low potassium results and low temperatures lead to falsely high results.