DIAGNOSIS OF CANINE CUSHINGS-SYNDROME BASED ON MULTIPLE STEROID ANALYSIS AND DEXAMETHASONE TURNOVER KINETICS

  • 1 January 1984
    • journal article
    • research article
    • Vol. 45  (11) , 2304-2309
Abstract
A comparison of cortisol concentrations, determined by high-performance iquid chromatography (HPLC) and radioimmunoassay, was made in healthy, mixed-breed dogs and in dogs with clinical signs of Cushing''s syndrome. Absolute concentration of cortisol was less in resting, dexamethasone-suppressed, and ACTH-stimulated plasma samples, when measured by HPLC relative to cortisol concentrations determined by radioimmunoassay. Diagnosis of Cushing''s syndrome could be made using either method. Plasma concentrations of cortisone and corticosterone were determined by HPLC. Cortisone and corticosterone concentrations alone were not diagnostic of Cushing''s syndrome; but when used in conjunction with cortisol determinations, they provided additional criteria for laboratory confirmation of the clinical diagnosis of Cushing''s syndrome. The clearance of exogenus dexamethasone used in the dexamethasone-suppression test was examined in the normal and cushingoid dogs. Plasma concentrations of exogenous dexamethasone were constant during the 3-h test in the normal dogs. In 75% of the dogs with Cushing''s syndrome, exogenous dexamethasone was cleared completely in the 3-h test. Dexamethasone clearance rates were excessively fast in most dogs with Cushing''s syndrome.

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