Plasma profiles of adrenocorticotropic hormone, cortisol, α-melanocyte-stimulating hormone, and growth hormone in dogs with pituitary-dependent hyperadrenocorticism before and after hypophysectomy

Abstract

The 6-h plasma profiles of adrenocorticotropic hormone (ACTH), cortisol, a-melanocyte-stimulating hormone (a-MSH), and GH were studied in 17 dogs with pituitarydependent hyperadrenocorticism (PDH) before and after hypophysectomy. The aim of the study was to investigate the relation between the hormone profile characteristics and recurrence of PDH after surgery.The hormones were secreted in a pulsatile fashion. The basal plasma cortisol concentration and area under the curve (AUC) for cortisol were significantly higher in the PDH cases than in eight controls. The characteristics of the plasma profiles of ACTH and a-MSH were not significantly different between the PDH cases and the controls. In the PDH cases, less GH was secreted in pulses than in the controls, but the difference was not significant. The basal plasma cortisol concentration, the AUC for ACTH and cortisol, and the pulse frequency of ACTH and cortisol decreased significantly after hypophysectomy for the group of PDH cases. The basal plasma concentrations of ACTH and a-MSH, the AUC for a-MSH, and the characteristics of the plasma GH profiles of the PDH cases remained unchanged after hypophysectomy. No pulses of a-MSH were observed after hypophysectomy. The co-occurrence between the ACTH and cortisol pulses decreased significantly with hypophysectomy. The postoperative pulse frequency of ACTH was the only characteristic with predictive value for the recurrence of PDH after hypophysectomy.The results of this study demonstrate that ACTH, cortisol, a-MSH, and GH are secreted in a pulsatile fashion in dogs with PDH. Hypophysectomy effectively reduces the secretion of ACTH and cortisol. The presence of ACTH pulses after hypophysectomy is a risk factor for the recurrence of hyperadrenocorticism.

Diagnosis of Spontaneous Canine Hyperadrenocorticism: 2012 ACVIM Consensus Statement (Small Animal)

“…A circadian rhythm has not been convincingly demonstrated, although 1 study reported higher plasma cACTH concentrations in late afternoon than in the morning . Concentrations of cACTH do not differ between healthy dogs and those with PDH, and its measurement is not useful to screen for HAC . Measurement of cACTH is the most accurate stand‐alone biochemical test for differentiating PDH from AT.…”

“…72 Concentrations of cACTH do not differ between healthy dogs and those with PDH, and its measurement is not useful to screen for HAC. 73 Measurement of cACTH is the most accurate stand-alone biochemical test for differentiating PDH from AT.…”

Lymphocytic Hypophysitis in a Dog with Diabetes Insipidus

“…Plasma concentrations of thyroid-stimulating hormone (TSH) and thyroxine (Kooistra et al, 2000), and GH and insulin-like growth factor-1 (IGF-1) (Fracassi et al, 2007) were decreased (Table 1), indicating hypopituitarism, secondary hypothyroidism and hyposomatotropism. The pituitaryeadrenocortical system was further investigated by measuring plasma concentrations of ACTH and a-melanocyte-stimulating hormone (MSH) by methods described previously (Hanson et al, 2006). The basal plasma concentration of ACTH was elevated and that of a-MSH was within the reference range (Table 1).…”

Accuracy of an Adrenocorticotropic Hormone (ACTH) Immunoluminometric Assay for Differentiating ACTH‐Dependent from ACTH‐Independent Hyperadrenocorticism in Dogs

“…16,[47][48][49][50] The samples studied here were ob-tained in the course of consultations during the morning and afternoon. The interest of clinicians in a diagnostic technique depends not only on its accuracy, but also on the practicality of the technique.…”