Sodium
Clinical Biochemistry
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
133 – 146 mmol/L (Source: Pathology Harmony Recommendations)
Clinical guidance
Sodium forms part of the standard U&E (urea and electrolyte) panel in blood. Please refer to LabTestsOnlineUK to learn more about sodium. https://labtestsonline.org.uk/tests/sodium-test
Notes
An artifactual rise in sodium due to sample contamination (sodium citrate or Cirta-Lock™) can be identified by measuring both serum chloride and osmolality. Pseudohypernatraemia (due to hypoproteinaemia) can also be excluded by measuring sodium via a direct ISE method.
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This information was last updated on 19 August 2026