Cobalamin is a water-soluble vitamin of the B group and an essential cofactor for nucleic acid synthesis and hematopoiesis. Because absorption of this vitamin is complex and requires intact pancreatic and ileal function, serum cobalamin concentration can be clinically used as a diagnostic and prognostic marker when assessing intestinal and pancreatic diseases in companion animals.1,2 Measurement of serum cobalamin concentration is generally considered a standard test in the diagnostic workup of cats and dogs with chronic gastrointestinal clinical signs.3
Traditionally, cobalamin has been considered a light-sensitive analyte.4–6 In the authors’ experience, serum samples submitted to diagnostic laboratories for cobalamin concentration measurement are frequently rejected when those samples have not been protected from light exposure. Even major commercial veterinary laboratories mandate that blood samples for cobalamin testing be protected from light after collection.a For this reason, requests for testing of stored samples are also often declined, which is inconvenient for patients, pet owners, and clinicians.
Information regarding the effects of sample storage conditions could help guide optimal preanalytical handling of samples submitted for cobalamin testing and be used in the development of recommendations on how to store specimens to ensure optimal results. However, to the authors’ knowledge, this information has not been reported in the veterinary literature. The purpose of the study reported here was to examine the effects of light exposure and storage temperature and duration on cobalamin concentration in serum samples from cats and dogs.
Presented in poster form at the 23th Congress of the European College of Veterinary Internal Medicine Companion Animals, Liverpool, England, September 2013.
Idexx Diavet AG, Postfach 43, Bäch, Switzerland.
Vitamin B12, Immulite 2000, Siemens Healthcare Diagnostics Inc, Newark, Del.
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