Use of a combination of routine hematologic and biochemical test results in a logistic regression model as a diagnostic aid for the diagnosis of hypoadrenocorticism in dogs

Abstract

OBJECTIVE To assess the discriminatory value for corticosteroid-induced alkaline phosphatase (CiALP) activity and other variables that can be measured routinely on a CBC and biochemical analysis for the diagnosis of hypoadrenocorticism in dogs. SAMPLE Medical records of 57 dogs with confirmed hypoadrenocorticism and 57 control dogs in which hypoadrenocorticism was suspected but ruled out. PROCEDURES A retrospective case-control study was conducted. Dogs were included if a CBC and complete biochemical analysis had been performed. Dogs with iatrogenic hypoadrenocorticism and dogs treated previously with glucocorticoids were excluded. Cortisol concentration for dogs with hypoadrenocorticism was ≤ 2 μg/dL both before and after ACTH administration. Cortisol concentration for control dogs was > 4 μg/dL before or after ACTH administration. RESULTS Area under the receiver operating characteristic (ROC) curve for CiALP activity was low (0.646; 95% confidence interval, 0.494 to 0.798). Area under the ROC curve for a model that combined the CiALP activity, Na-to-K ratio, eosinophil count, activity of creatine kinase, and concentrations of SUN and albumin was high (0.994; 95% confidence interval, 0.982 to 1.000). Results for this model could be used to correctly classify all dogs, except for 1 dog with hypoadrenocorticism and no electrolyte abnormalities. CONCLUSIONS AND CLINICAL RELEVANCE CiALP activity alone cannot be used as a reliable diagnostic test for hypoadrenocorticism in dogs. Combined results for CiALP activity, Na-to-K ratio, eosinophil count, creatine kinase activity, and concentrations of SUN and albumin provided an excellent means to discriminate between hypoadrenocorticism and diseases that mimic hypoadrenocorticism.

Characterization of clinicopathologic and abdominal ultrasound findings in dogs with glucocorticoid deficient hypoadrenocorticism

“…A clinician may be prompted to test for GDH if clinicopathologic or ultrasonographic findings such as hypocholesterolemia, lymphocytosis, or small adrenal glands on abdominal ultrasound are observed. 2,5,[7][8][9]13 Given our results, reliance on any of these findings may be problematic, because substantial overlap was observed in these variables between dogs with GDH and controls.…”

“…[5][6][7] For example, hypoglycemia and eosinophilia are present in fewer than 33% of dogs with GDH. 5,7,8 A recent study comparing dogs that were presented for chronic GI signs did not find any significant differences in hematologic or biochemical variables between dogs with GDH and those with chronic enteropathy. 2 The overlap in clinical signs in these patients can result in a substantial diagnostic challenge for clinicians.…”

Atypical hypoadrenocorticism in a dog with chronically elevated serum alanine aminotransferase (ALT) activity

“…A recent comparison of biochemical data in dogs with hypoadrenocorticism found significant elevations in ALT with atypical hypoadrenocorticism compared with control dogs, but did not with typical hypoadrenocorticism. Clinical categorisation, however, is impossible based on ALT alone, as values ranged drastically in all groups despite small differences in the overall average 7…”

Evaluation of a machine learning tool to screen for hypoadrenocorticism in dogs presenting to a teaching hospital

“…Hypoadrenocorticism (HA) in dogs is caused most commonly by immune mediated destruction of the adrenal cortex with subsequent deficiencies in hormone production. Most cases of CHA lack both glucocorticoids and mineralocorticoids (GMDH); in 30% to 40% of dogs, glucocorticoid deficiency (GDH) is diagnosed without overt mineralocorticoid deficiency 1,2 . Clinical presentations of HA can vary widely, and signs can be vague and episodic 3 .…”

“…[3][4][5] Characteristic clinicopathologic findings that are associated with HA include hyponatremia, hyperkalemia, and azotemia that are associated with aldosterone deficiency, and hypoalbuminemia, hypocholesterolemia, hypoglycemia, and lack of a stress leukogram that are associated with cortisol deficiency. 2,6,7 Observing all, or some, of these abnormalities in a dog with compatible clinical signs should prompt the clinician to test for HA. However, in many cases, these variables can be within the normal reference range, and these variables alone are neither sensitive nor specific for the screening of HA.…”