Turnaround times
The quoted turnaround time is from sample receipt in the laboratory, to results authorisation in the Laboratory Information Management system. The times do not include transport of specimen to the laboratory or the administrative process to print and post/email reports. Service users must allow for transport and reporting time when ordering tests.
Clinical background:
Serum osmolality is a useful initial test when investigating the cause of hyponatraemia and in identifying a raised osmolal gap for suspected poisoning.
Calculated osmolarity = 2 (Na+) + glucose + urea
The difference between the measured osmolality and the calculated is known as the osmolal gap and is normally less than 10 mOsm/kg.
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 sample: Unknown
Separated samples:12 hrs at 20-25C
3 days at 4-8C
3 months at -20C
Reference ranges:
275-295 mmol/Kg