Use of the urine cortisol: creatinine ratio to monitor treatment response in dogs with pituitary-dependent hyperadrenocorticism.
OBJECTIVE
To determine the usefulness of measuring urine cortisol:creatinine ratio (UCCR) as a means of monitoring response to mitotane treatment in dogs with pituitary-dependent hyperadrenocorticism (PDH).


METHODS
Case series.


METHODS
51 clinically normal dogs and 21 dogs with PDH.


METHODS
The reference range for the UCCR was determined by measuring the ratio in 51 clinically normal dogs. The usefulness of measuring UCCR in evaluating response of 21 dogs with PDH to treatment with mitotane was evaluated by comparing ACTH-stimulated blood cortisol concentrations with UCCR at the end of the induction phase of treatment (13 dogs) and during the maintenance phase of treatment (21).


RESULTS
UCCR was not useful for identifying dogs with inadequate adrenal reserves at the end of the induction phase of treatment or during the maintenance phase. The UCCR was useful for identifying dogs in which control of cortisol secretion was not adequate.


CONCLUSIONS
UCCR should not be used for evaluation of dogs during the induction phase of treatment, because the potential consequences of not identifying dogs with inadequate adrenal reserves are great. The UCCR may be useful as an adjunct means of monitoring treatment response during the maintenance phase of treatment. However, the ACTH stimulation test remains a necessary component when monitoring response to treatment in dogs with PDH receiving mitotane.
Guptill
L
L
Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Purdue University, West Lafayette, IN 47907, USA.
Scott-Moncrieff
J C
JC
Bottoms
G
G
Glickman
L
L
Johnson
M
M
Glickman
N
N
Nelson
R
R
Bertoy
E
E
D000308:Adrenocortical Hyperfunction / Q000188:drug therapy / Q000652:urine / Q000662:veterinary*; D000818:Animals; D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use; D003404:Creatinine / Q000652:urine*; D004283:Dog Diseases / Q000175:diagnosis / Q000188:drug therapy / Q000652:urine*; D004285:Dogs; D005260:Female; D006854:Hydrocortisone / Q000652:urine*; D008297:Male; D008939:Mitotane / Q000627:therapeutic use; D011863:Radioimmunoassay / Q000662:veterinary; D012016:Reference Values; D015203:Reproducibility of Results
D018931:Antineoplastic Agents, Hormonal; D008939:Mitotane; D003404:Creatinine; D006854:Hydrocortisone