title: Feline plasma cortisol (hydrocortisone) measured by radioimmunoassay.
abstract: Plasma cortisol (hydrocortisone) was measured by radioimmunoassay in 6 normal cats. Blood was collected from the cats by venipuncture at intervals of 3 hours for 3 days. Resting plasma cortisol concentrations averaged 17.0 +/- 2.8 (SD) ng/ml and ranged from nondetectable (less than 3 ng/ml) to 82.8 ng/ml. Of 144 plasma samples, 95% contained less than 40 ng of cortisol/ml. Circadian rhythm of cortisol secretion was not detected, suggesting that adrenal function tests may be started in feline patients at any time of day. Intramuscular injection of 2.2 U of ACTH gel/kg of body weight caused detectable increase in plasma cortisol concentrations at 1 and 2 hours after injection. Maximal response to ACTH in the 6 cats ranged from 41.6 to 178.4 ng/ml. Oral administration of 0.1 mg of dexamethasone/kg suppressed plasma cortisol to nondetectable concentrations for 32 hours in 5 of the 6 cats.
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000494:pharmacology; D000818:Animals; D002415:Cats / Q000097:blood*; D002940:Circadian Rhythm; D003907:Dexamethasone / Q000494:pharmacology; D005260:Female; D006854:Hydrocortisone / Q000097:blood*; D008297:Male; D011863:Radioimmunoassay / Q000379:methods / Q000662:veterinary
chemical_list: D003907:Dexamethasone; D000324:Adrenocorticotropic Hormone; D006854:Hydrocortisone