Storage of Serum or Whole Blood Samples? Effects of Time and Temperature on 22 Serum Analytes

ArticleinEuropean journal of clinical chemistry and clinical biochemistry: journal of the Forum of European Clinical Chemistry Societies 33(4):231-8 · April 1995with136 Reads
DOI: 10.1515/cclm.1995.33.4.231 · Source: PubMed
Information on the stability of serum analytes during storage of serum or whole blood samples is often incomplete and sometimes contradictory. Using a widely available analyser (Hitachi 737/Boehringer), we therefore determined the effects of storage time and temperature on the measured concentrations of the following serum analytes: sodium, potassium, calcium, chloride, inorganic phosphate, magnesium, creatinine, urea, uric acid, bilirubin, cholesterol, HDL- and LDL-cholesterol, triacylglycerols, creatine kinase, aspartate aminotransferase, alanine aminotransferase, γ-glutamyltransferase, alkaline phosphatase, α-amylase, lactate dehydrogenase and cholinesterase. When separated serum was stored at + 9 °C for seven days, the mean changes in inorganic phosphate and lactate dehydrogenase exceeded significantly (p < 0.05 or 0.001, respectively) the maximum allowable inaccuracy according to the Guidelines of the German Federal Medical Council; all other quantities were sufficiently stable. In serum at room temperature, inorganic phosphate, uric acid, HDL-cholesterol and triacylglycerols increased continuously, whereas bilirubin, LDL-cholesterol, creatine kinase and aspartate aminotransferase decreased more than the guidelines permit during the storage period (p < 0.05 for asparate aminotransferase, p < 0.001 for the other analytes mentioned). In whole blood stored for 7 days at + 9 °C, only the following serum analytes satisfied the stability requirements of the guidelines: calcium, urea, cholesterol, HDL-cholesterol, LDL-cholesterol, triacylglycerols, creatine kinase, γ-glutamyltransferase and cholinesterase. When stored at room temperature, only sodium, uric acid, bilirubin, cholesterol, triacylglycerols, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, m-amylase and cholinesterase were still stable after 3 days. The data collected show that all quantities examined are sufficiently stable for four days in separated serum stored at + 9 °C.
    • "This phenomenon of increased signal when using polyclonal antibodies was demonstrated by Jain et al., where a rabbit polyclonal antibody recognized fragments of the protein in question whereas the monoclonal antibody did not [18] . Other factors that can affect levels during sample storage include prolonged contact of serum with erythrocytes leading to exchange of substances and either dilution or increase of concentration, hemolysis (again causing either dilution or increase concentration), and interference of hemoglobin in the measurement (specifically in the photometric quantification of constituents) [19]. Overall, these findings are consistent with Kainos' instructions of stability after six thaw/freeze cycles and stability at −80 °C for 3 years [13]. "
    [Show abstract] [Hide abstract] ABSTRACT: There is growing need for a reliable assay for measuring fibroblast growth factor 23 (FGF23), a regulator of phosphorus and vitamin D. In this work, we analyze and compare the performance of three available assays, including the effect of temperature and time. This knowledge will allow for better understanding of FGF23 in the future. Introduction: Intact and C-terminal FGF23 (iFGF23 and cFGF23) concentrations are important in the diagnosis of hypo- and hyperphosphatemic diseases. The effects of temperature, storage, and specimen handling on FGF23 levels are not well known.We investigated the effects of various factors on plasma and serum measurement of FGF23 using three different assays. Methods: Serum and plasma FGF23 were measured using three commercially available ELISA assays—two measuring iFGF23 and one measuring cFGF23. Samples from subjects with known FGF23 disorders were stored at 4, 22, and 37 °C and analyzed at different intervals up to 48 hours (h). A subset of samples underwent repeated freeze-thaw cycles, and samples frozen at −80 °C for up to 60 months were reanalyzed. The effect of adding a furin convertase inhibitor on FGF23 degradation was investigated using samples stored at 37 °C for 48 h. Intact FGF23 levels were measured from plasma samples of four different groups to test the correlation of the two assays. Results: Plasma FGF23 levels were stable when stored at 4 and 22 °C for 48 h. Both plasma and serum FGF23 levels demonstrated relative stability after five freeze-thaw cycles. Long-term storage at −80 °C for 40 months induced some variability in FGF23 levels. The addition of a furin inhibitor did not affect FGF23 degradation. Intact FGF23 levels showed good correlation only at the upper limit of the assay range when comparing the two assays. Conclusions: Sample type, handling, and choice of assay are factors that affect FGF23 levels and should be considered when measuring this hormone.
    Full-text · Article · Feb 2016
    • "Phosphorus levels were found to be significantly increased (p<0.001) with storage duration, from 11.86 ± 0.62 mg/dL at 0 day to 16 ± 0.88 mg/dL at 21st day. Whole blood contains many phosphatases which cause hydrolysis of phosphate esters resulting in increase in inorganic phosphate levels [14]. In addition CPDA also has phosphates in it resulting in increased levels [4]. "
    Full-text · Article · Jan 2015 · Clinica Chimica Acta
    • "Separator tubes contain a polymer gel that reversibly liquefies during centrifugation, forming a barrier between serum/plasma and cells. Whilst phosphate concentration has been reported to increase markedly in uncentrifuged gel tubes stored at room temperature for 1 day456, stability in centrifuged tubes, particularly over longer periods and at the high concentrations seen in renal patients, is less certain [3,5,7]. Using delays in sample processing that might typically be expected, we have investigated whether gel barrier separator tubes, centrifuged prior to posting, enable reliable measurement of phosphate concentration. "
    Full-text · Article · Sep 2014
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