Sodium (Na)
Chemical Pathology
Notes
Sodium forms part of the standard U&E (urea and electrolyte) panel in blood and can also be assayed in urine.
Sample requirements
For adults, blood taken into a 5mL gold top gel tube (or rust top for the Acute Unit)
For children, blood taken into a 3.5mL rust top gel tube
For neonates, blood taken into a 0.8mL minicollect lithium heparin tube. Please list the tests of particular interest so that some priority can be given to analysis if plasma volumes are small.
For 24 hour urine sodium, urine should be collected into a brown 3L urine bottle
For random urine sodium, send in a plain white top narrow tube
Storage/transport
Do not store blood samples. Send at ambient temperature to the laboratory as soon as possible (no greater than 8 hours). Urine samples can be stored refrigerated overnight if clinically appropriate and unavoidable.
Required information
Relevant clinical details including medication, fluid replacement. 24 hour urine colelctions should clearly state start and finish dates and times of collection.
The labelling of the request form and the sample must conform to the Policy for Specimen and Request Form Labelling for Pathology Users
Turnaround times
The assays are 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 ranges
Serum sodium 133 - 146 mmol/L
Adult 24 hour urine sodium 40 - 220 mmol/24 h
Further information
Analyte Monograph alongside the National Laboratory Medicine Handbook