Evaluation of resting cortisol concentration testing in dogs with chronic gastrointestinal signs

Abstract

Background Resting cortisol concentrations are routinely measured in dogs with chronic gastrointestinal signs to rule out hypoadrenocorticism based on a concentration >2 μg/dL (>55 nmol/L). Hypothesis/Objectives To assess the cross‐sectional prevalence of hypoadrenocorticism in a group of dogs with chronic gastrointestinal signs presented to a referral internal medicine service. Animals Two‐hundred and eighty‐two client‐owned dogs with chronic gastrointestinal signs and with resting cortisol concentration testing performed. Methods Retrospective review of medical records (final diagnosis, resting cortisol concentration, and adenocorticotropic hormone [ACTH] stimulation test results) of a referral population of dogs between May 2013 and September 2017. Results Resting cortisol concentration was <2 μg/dL (<55 nmol/L) in 79 patients (28%). Repeated resting cortisol concentration measurements were performed in 28 dogs, and in 8, resting cortisol concentrations remained <2 μg/dL (<55 nmol/L). Post‐ACTH cortisol concentration was <2 μg/dL (<55 nmol/L) in 1 dog, consistent with a diagnosis of hypoadrenocorticism and giving a prevalence estimate of hypoadrenocorticism in this population of dogs of 0.3% (95% confidence interval [95CI], 0.03‐1.5%). In 19 dogs with an initial resting cortisol concentration <2 μg/dL (<55 nmol/L), hypoadrenocorticism was excluded based on a repeat resting cortisol concentration >2 μg/dL (>55 nmol/L). Overall, the most common diagnosis was chronic primary inflammatory enteropathy (176/282, 62.4%), followed by extragastrointestinal neoplasia (17/282, 6%), protein‐losing enteropathy, pancreatitis and megaesophagus (10/282, 3.5% each). Conclusions and Clinical Importance Although dogs with hypoadrenocorticism can present with chronic gastrointestinal signs, it was the final diagnosis in only 1 of 282 dogs presenting to a referral internal medicine service for signs of chronic enteropathy. Repeated resting cortisol concentration may be considered as a test to try and exclude hypoadrenocorticism.

Prevalence of eunatremic, eukalemic hypoadrenocorticism in dogs with signs of chronic gastrointestinal disease and risk of misdiagnosis after previous glucocorticoid administration

“…In this multicenter prospective study, the prevalence of EEH in a cohort of dogs with CGD presented to 2 referral institutions was 0.9% (95% CI, 0.1%‐4.8%). The estimated prevalence in the present study closely corresponded with the overall prevalence of HA in the general canine population (between 0.06% and 1.1%), 1,22‐24 and with that recently reported in a large group of dogs with signs of CGD 16 . However, the results of this study demonstrated a lower prevalence of EEH than previously described in dogs with signs of CGD presented to several referral centers in Germany and in the Netherlands 15 .…”

“…15 In the latter study, 6 of the 151 (4%) dogs with signs of CGD were diagnosed with HA and none of these dogs had abnormalities in serum electrolyte concentrations. 15 Unfortunately, as in many other studies, 5,15,16,26 eACTH was not measured which might have led to an overestimation of the true prevalence of EEH. Moreover, it remains unknown whether those cases suffered from primary HA or if some of them might have had secondary HA.…”

“…[11][12][13] However, because of the low specificity of the test (20%-78.2%), up to 33% of dogs with CGD, but without HA, have a BSC <2 μg/dL (<55 nmol/L). [11][12][13][14][15][16] For this reason, urine cortisol-to-creatinine ratio (UCCR) and cortisol-to-ACTH ratio (CAR) have been proposed as alternative screening tests for HA in dogs. 14,[17][18][19] Even though the ACTHst remains the gold standard for HA diagnosis, previous glucocorticoid administration (PGA), commonly used in dogs with signs of CGD, can give false positive results.…”

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

“…From a clinical perspective, the consequences of a false positive result are acceptable, as the confirmatory testing is noninvasive and cost effective. In contrast, recent studies have demonstrated that as a screening test, even when used in a population with higher pretest probability, the baseline cortisol test is associated with a higher false positive rate 1,15 . The MLM might therefore be used not only to automatically screen patients for HA, but also refine test selection and save money in HA suspects.…”

“…In contrast, recent studies have demonstrated that as a screening test, even when used in a population with higher pretest probability, the baseline cortisol test is associated with a higher false positive rate. 1,15 The MLM might therefore be used not…”