The influence of storage time and temperature on the measurement of serum, plasma and urine osmolality.
Author(s): Bezuidenhout K, Rensburg MA, Hudson CL, Essack Y, Davids MR
Publication: Ann Clin Biochem, 2016, Vol. 53, Page 452-8
PubMed ID: 26462927 PubMed Review Paper? No
Purpose of Paper
This paper investigated effects of delayed centrifugation on the osmolality of serum, lithium-heparin plasma, and urine from patients with hyperglycaemia, hyponatraemia, or renal failure and from healthy individuals.
Conclusion of Paper
Although there were significant effects that exceeded the total allowable error of storing blood at room temperature on serum and plasma osmolality and of storing blood at 4-8˚C on plasma osmolality, none of the changes exceeded the reference change value. The osmolality of urine was not significantly affected by up to 36 h of storage at either temperature.
Studies
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Study Purpose
This study investigated the effects of delayed centrifugation on the osmolality of serum, lithium-heparin plasma, and urine from 16 patients with hyperglycaemia, hyponatraemia, or renal failure and from 25 healthy individuals. Blood was collected into 11 serum-separating tubes and 11 lithium heparin tubes and stored at room temperature or 4-8˚C for 30 min or 3, 6, 12, 24, or 36 h before centrifugation at an unspecified speed. Similarly, a urine specimen from each individual was aliquoted and stored at room temperature or 4-8˚C for 30 min or 3, 6, 12, 24 and 36 h before centrifugation. For the 16 patient specimens, osmolality was determined by freezing-point depression using an advanced Micro-Osmometer 3320 and osmality in specimens from the healthy individuals was determined using the Micro-Osmometer 3300.
Summary of Findings:
Osmolality in serum and plasma increased by 3.5 mosmol/kg (both, P<0.005 and P<0.001, respectively) when blood was stored at room temperature for 24 h and the osmolality of serum was 6.4 mosmol/kg (P<0.005) higher and the osmolality of plasma was 3.3 mosmol/kg (P<0.05) higher when blood was stored for 36 h at room temperature than when blood was centrifuged after 30 min. Although serum osmolality was not affected by storage of blood for up to 36 h at 4-8˚C, the osmolality of plasma was 2.1 mosmol/kg lower when blood was stored for 12 h rather than 30 min prior to centrifugation (P=0.04), but no other significant effects of refrigerated storage of blood on plasma osmolality were observed. Importantly, while the changes were statistically significant and exceeded the total allowable error, none of the changes exceeded the reference change value of 4.1%. In contrast, the osmolality of urine was unaffected by up to 36 h of storage at either temperature.
Biospecimens
Preservative Types
- None (Fresh)
Diagnoses:
- Normal
- Other diagnoses
Platform:
Analyte Technology Platform Electrolyte/Metal Clinical chemistry/auto analyzer Small molecule Clinical chemistry/auto analyzer Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Biospecimen Aliquots and Components Centrifugation Centrifugation delays investigated
Storage Storage duration 30 min
3 h
6 h
12 h
24 h
36 h
Storage Storage temperature 4-8˚C
Room temperature