Effects of storage conditions and duration on cobalamin concentration in serum samples from cats and dogs

Abstract

OBJECTIVE To evaluate the effects of storage conditions and duration on cobalamin concentration in serum samples from dogs and cats. DESIGN Experiment. SAMPLE Serum samples from 9 client-owned cats and 9 client-owned dogs. PROCEDURES Serum harvested from freshly obtained blood samples was separated into 11 aliquots/animal. One aliquot (baseline sample) was routinely transported in light-protected tubes to the laboratory for cobalamin assay; each of the remaining aliquots was stored in a refrigerator (6°C; n = 5) or at room temperature (20°C) with exposure to daylight (5) for 24, 48, 72, 96, or 120 hours. Aliquots were subsequently wrapped in aluminum foil, frozen (-20°C), and then transported to the laboratory for measurement of cobalamin concentration, all in the same run. Percentage decrease in cobalamin concentration from baseline was analyzed by means of linear mixed modeling. RESULTS No differences in cobalamin values were identified between cats and dogs; therefore, data for both species were analyzed together. Median baseline serum cobalamin concentration was 424 ng/L (range, 178 to 1,880 ng/L). Values for serum samples stored with daylight exposure at room temperature were significantly lower over time than were values for refrigerated samples. Although values for refrigerated samples did not decrease significantly from baseline values over time, values for the other storage condition did; however, the mean percentage decrease for serum samples stored at room temperature was small (0.14%/h; 95% confidence interval, 0.07% to 0.21%/h). CONCLUSIONS AND CLINICAL RELEVANCE Overall, serum cobalamin concentration appeared stable for 5 days when feline and canine serum samples were refrigerated at 6°C. The effect of light and room temperature on serum cobalamin concentration, although significant, was quite small for samples stored with these exposures for the same 5-day period.

Prospective long‐term evaluation of parenteral hydroxocobalamin supplementation in juvenile beagles with selective intestinal cobalamin malabsorption (Imerslund‐Gräsbeck syndrome)

“…The reason for the discrepancy between serum Cbl and urinary MMA concentrations currently is unclear. It is unlikely that pre‐analytical factors played a role because samples were routinely processed and it was recently shown that the effects of extended light exposure and room temperature on serum Cbl concentrations were very small . It is possible that the half‐life of Cbl bound intracellularly as a coenzyme is longer than the residence time of Cbl in the circulation, which would mean that Cbl continues to be active in tissues and Cbl‐dependent metabolism remains normal even when serum concentrations are low.…”

Review of cobalamin status and disorders of cobalamin metabolism in dogs

“…Therefore, other markers that more closely reflect the intracellular availability of cobalamin such as the serum concentration of HCY and MMA should ideally be included when assessing cobalamin status . Cobalamin is stable in serum even if samples are not strictly protected from light . Thus, in clinical practice, measurement of serum cobalamin can be conveniently performed in serum samples that are archived for up to 5 days.…”

Exposure to Toxoplasma gondii in Asian Elephants (Elephas maximus indicus) in Thailand

“…The long-term storage of serum affects the stability of several biochemical components and immunoglobulins in human and animal sera [39][40][41]. This could be impacted on the serological tests in our study because most of serum samples were stored for a long time.…”

“…Purified recombinant T. gondii dense granular antigen 8 (TgGRA8) was prepared as described previously [40]. Briefly, TgGRA8 (582 bp) was amplified using polymerase chain reaction and then ligated into a pET-21a vector using NdeI and XhoI as the cloning sites (General Biosystems, Durham, NC, USA) that were transfected into Escherichia coli strain Rosetta (DE3) cells.…”