COMBINED DEXAMETHASONE SUPPRESSION AND COSYNTROPIN (SYNTHETIC ACTH) STIMULATION TEST IN THE DOG - NEW APPROACH TO TESTING OF ADRENAL-GLAND FUNCTION

  • 1 January 1980
    • journal article
    • research article
    • Vol. 41  (8) , 1243-1246
Abstract
A combined dexamethasone suppression and cosyntropin (synthetic ACTH) stimulation test was developed in the dog so that information concerning pituitary gland (hypophysis) and adrenal gland competence could be provided in a single trial, during a short time span. Treatment of dogs with dexamethasone (0.1 mg/kg i.m.) resulted in total suppression (below assay sensitivity or < 10 ng/ml) of plasma hydrocortisone (cortisol) at postinjection hour (PIH) 2 in 100% of the dogs, whereas suppression was inconsistent at PIH 1. Cosyntropin (0.5 U[unit]/kg i.v.) administration to normal or dexamethasone-suppressed dogs increased plasma hydrocortisone concentration 3.5-4.5 times baseline values at PIH 1, which was the time of maximal effect. The combined test concept for adrenal gland function is valid, convenient (3 sample collections; 3 h period), and allows testing of adrenal gland response to dexamethasone suppression and ACTH stimulation in a single trial. The following test procedure for dogs is recommended: collect baseline plasma sample (0900 h) followed by dexamethasone injection (0.1 mg/kg i.m.); collect 2nd plasma sample 2 h after dexamethasone (to evaluate suppression of plasma hydrocortisone concentration) followed by the cosyntropin injection (0.5 U/kg i.v.); and collect a 3rd plasma sample 1 h later to evaluate plasma hydrocortisone concentration after cosyntropin stimulation.