Sodium, serum

Sodium, serum
S -Na KL 2382 

Sodium is the most important cation in the extracellular fluid compartment. Serum sodium testing is an essential part of monitoring the fluid and electrolyte balance. Excessively high sodium concentrations in serum are due to dehydration (diarrhoea, vomiting, impaired production of fluid balance-controlling hormones), while excessively low concentrations are due to accumulation of water in the body (cardiac insufficiency, impaired renal function or impaired production of fluid balance-controlling hormones). 


Monitoring fluid and electrolyte balance.


1 mL of serum (or Li-heparin plasma), minimum 0.5 mL. Separated plasma can be stored refrigerated for three days. Freeze the sample for longer storage.

Storage and delivery 

Delivery at room temperature, if it arrives within 24 hours. Can be stored refrigerated over the weekend. 


Ion selective electrode (ISE)

Turnaround time

1 – 2 weekdays

Reference ranges

137 – 145 mmol/L