FELINE PLASMA CORTISOL (HYDROCORTISONE) MEASURED BY RADIOIMMUNOASSAY

  • 1 January 1979
    • journal article
    • research article
    • Vol. 40  (2) , 190-192
Abstract
Plasma cortisol (hydrocortisone) was measured by radioimmunoassay in 6 normal cats. Blood was collected from the cats by venipuncture at 3 h intervals for 3 days. Resting plasma cortisol concentrations averaged 17.0 .+-. 2.8 (SD) ng/ml and ranged from nondetectable (< 3 ng/ml) to 82.8 ng/ml. Of 144 plasma samples, 95% contained < 40 ng 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. I.m. injection of 2.2 U [units] of ACTH gel/kg of body wt caused detectable increase in plasma cortisol concentrations at 1 and 2 h after injection. Maximal response to ACTH in the 6 cats ranged from 41.6-178.4 ng/ml. Oral administration of 0.1 mg dexamethasone/kg suppressed plasma cortisol to nondetectable concentrations for 32 h in 5 of 6 cats.