EFFECTS OF STORAGE ON CONCENTRATION OF HYDROCORTISONE (CORTISOL) IN CANINE SERUM AND PLASMA

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  • 1 January 1981
    • journal article
    • research article
    • Vol. 42  (9) , 1618-1620
Abstract
A specific radioimmunoassay was used to measure concentrations of hydrocortisone (cortisol) in the serum and plasma of 4 dogs. Differences (P > 0.05) in concentrations of cortisol were not found between serum and plasma (from EDTA-treated and heparinized blood samples). Differences (P > 0.05) in serum or plasma concentrations of cortisol were not found between samples stored at 4.degree. C for various times (10 min, 10 h, 40 h) after collection, but before removal of red blood cells. To determine the stability of cortisol in serum samples stored at room temperature, degradation was dependent on the initial serum concentrations of cortisol. Decreases (P > 0.05) did not occur in concentrations of cortisol in serum samples stored up to 15 days when initial concentrations of cortisol were less than 15 ng/ml. When initial concentrations of cortisol were .apprx. 55 and 80 ng/ml, significant (P > 0.05) degradation occurred after 9 and 5 days of storage, respectively. Either serum or plasma of dogs evidently is suitable for radioimmunoassay of cortisol, and samples (with and without added coagulants) incubated at 4.degree. C may be left uncentrifuged for up to 40 h without cortisol degradation. Prolonged storage of serum at room temperature is detrimental, particularly for samples having large concentrations of cortisol.