Urinary cortisol‐creatinine ratio in dogs with hypoadrenocorticism

Abstract

Background Basal serum cortisol (BSC) ≥2 μg/dL (>55 nmol/L) has high sensitivity but low specificity for hypoadrenocorticism (HA). Objective To determine whether the urinary corticoid:creatinine ratio (UCCR) can be used to differentiate dogs with HA from healthy dogs and those with diseases mimicking HA (DMHA). Animals Nineteen healthy dogs, 18 dogs with DMHA, and 10 dogs with HA. Methods Retrospective study. The UCCR was determined on urine samples from healthy dogs, dogs with DMHA, and dogs with HA. The diagnostic performance of the UCCR was assessed based on receiver operating characteristics (ROC) curves, calculating the area under the ROC curve. Results The UCCR was significantly lower in dogs with HA (0.65 × 10−6; range, 0.33‐1.22 × 10−6) as compared to healthy dogs (3.38 × 10−6; range, 1.11‐17.32 × 10−6) and those with DMHA (10.28 × 10−6; range, 2.46‐78.65 × 10−6) (P < .0001). There was no overlap between dogs with HA and dogs with DMHA. In contrast, 1 healthy dog had a UCCR value in the range of dogs with HA. The area under the ROC curve was 0.99. A UCCR cut‐off value of <1.4 yielded 100% sensitivity and 97.3% specificity in diagnosing HA. Conclusions and Clinical Importance The UCCR seems to be a valuable and reliable screening test for HA in dogs. The greatest advantage of this test is the need for only a single urine sample.

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

“…This raises the question of whether BSC concentration should be measured in all dogs with signs of CGD. For this reason, the CAR and the UCCR have been proposed as alternative screening tests for HA in dogs 14,17‐19 . The CAR is a valuable and reliable tool for diagnosing primary HA, the advantage of which is that only a single blood sample needed 14,17 .…”

“…For this reason, the CAR and the UCCR have been proposed as alternative screening tests for HA in dogs. 14 , 17 , 18 , 19 The CAR is a valuable and reliable tool for diagnosing primary HA, the advantage of which is that only a single blood sample needed. 14 , 17 However, the diagnostic utility of this test can be limited in clinical practice owing to the critical sampling collection and handling needed for eACTH measurement.…”

“…[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. In previous studies, PGA was excluded based only on the history of the dog which likely led to an overdiagnosis of EEH.…”

“…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) 11‐16 . 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 14,17‐19 …”

“… 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 …”