post-ACTH Cortisol Concentrations Research Articles

The effects of selected sedatives on basal and stimulated serum cortisol concentrations in healthy dogs.

Hormone assessment is typically recommended for awake, unsedated dogs. However, one of the most commonly asked questions from veterinary practitioners to the endocrinology laboratory is how sedation impacts cortisol concentrations and the adrenocorticotropic hormone (ACTH) stimulation test. Butorphanol, dexmedetomidine, and trazodone are common sedatives for dogs, but their impact on the hypothalamic-pituitary-adrenal axis (HPA) is unknown. The objective of this study was to evaluate the effects of butorphanol, dexmedetomidine, and trazodone on serum cortisol concentrations. Twelve healthy beagles were included in a prospective, randomized, four-period crossover design study with a 7-day washout. ACTH stimulation test results were determined after saline (0.5 mL IV), butorphanol (0.3 mg/kg IV), dexmedetomidine (4 µg/kg IV), and trazodone (3-5 mg/kg PO) administration. Compared to saline, butorphanol increased basal (median 11.75 µg/dL (range 2.50-23.00) (324.13 nmol/L; range 68.97-634.48) vs 1.27 µg/dL (0.74-2.10) (35.03 nmol/L; 20.41-57.93); P < 0.0001) and post-ACTH cortisol concentrations (17.05 µg/dL (12.40-26.00) (470.34 nmol/L; 342.07-717.24) vs 13.75 µg/dL (10.00-18.90) (379.31 nmol/L; 275.96-521.38); P ≤ 0.0001). Dexmedetomidine and trazodone did not significantly affect basal (1.55 µg/dL (range 0.75-1.55) (42.76 nmol/L; 20.69-42.76); P = 0.33 and 0.79 µg/dL (range 0.69-1.89) (21.79 nmol/L; 19.03-52.14); P = 0.13, respectively, vs saline 1.27 (0.74-2.10) (35.03 nmol/L; 20.41-57.93)) or post-ACTH cortisol concentrations (14.35 µg/dL (range 10.70-18.00) (395.86 nmol/L; 295.17-496.55); (P = 0.98 and 12.90 µg/dL (range 8.94-17.40) (355.86 nmol/L; 246.62-480); P = 0.65), respectively, vs saline 13.75 µg/dL (10.00-18.60) (379.31 nmol/L; 275.86-513.10). Butorphanol administration should be avoided prior to ACTH stimulation testing in dogs. Further evaluation of dexmedetomidine and trazodone's effects on adrenocortical hormone testing in dogs suspected of HPA derangements is warranted to confirm they do not impact clinical diagnosis.

The impact of single-dose trazodone administration on plasma endogenous adrenocorticotropic hormone and serum cortisol concentrations in healthy dogs.

Conditions affecting the hypothalamic-pituitary-adrenal (HPA) axis are common in dogs. Testing the function of the HPA axis includes measurement of endogenous adrenocorticotropic hormone (eACTH) and performance of an adrenocorticotropic hormone (ACTH) stimulation test. Trazodone is commonly administered to dogs to decrease stress. In humans, trazodone significantly decreases plasma cortisol concentration via alpha-1 adrenergic activity. Determine the influence of trazodone on eACTH and serum cortisol concentrations in healthy dogs. Fourteen healthy, adult, companion dogs. Prospective, randomized placebo-controlled study. Trazodone (8-10 mg/kg) or placebo was administered PO 1 hour before eACTH measurement and ACTH stimulation testing. After a ≥7-day wash-out period, dogs received the opposite treatment. Differences in eACTH, pre- and post-ACTH stimulation cortisol concentrations, and delta (difference between pre- and post-ACTH) cortisol concentrations were analyzed using a paired t or signed-rank test with a P < .05 significance level. The eACTH concentrations were not significantly different (P = .23) between treatments. Similarly, no significant differences were found in the pre-ACTH cortisol concentrations between treatments (P = .40). Post-ACTH cortisol concentrations (P = .05) and delta cortisol concentrations (P = .04) were significantly lower when the dogs were treated with trazodone. Preliminary data suggest trazodone administration dampens the adrenocortical response to stimulation in healthy dogs. If similar effects are found in dogs with adrenal disease, the use of trazodone may affect diagnosis and clinical decision making in these populations.

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

Clinical findings of glucocorticoid-deficient hypoadrenocorticism (GDH) can overlap with other diseases, presenting a diagnostic challenge. Describe clinicopathologic and ultrasonographic features of dogs with GDH and those suspected of having GDH that had the disease ruled out. Six hundred twenty-three dogs. Records from dogs with suspected GDH between 2003 and 2018 were reviewed. Dogs with hyperkalemia or hyponatremia were excluded. Dogs were categorized as controls when the resting serum cortisol or post-ACTH cortisol concentration were > 2 μg/dL. Clinicopathologic and ultrasonographic features were compared between groups. The optimal cut-point, area under the receiver operating characteristic curve (AUC), sensitivity, and specificity were calculated for individual features used to detect GDH. Dogs were categorized as GDH (n=29) or controls (n=594). Lymphocyte count (>1750 cells/L; sensitivity, 96.6%; 95% confidence interval [CI], 82.8%-99.8%; specificity, 60.3%; 95% CI, 56.3%-64.1%; AUC, 0.828; 95% CI, 0.762-0.894) and albumin/globulin ratio (<1.081; sensitivity, 86.2%; 95% CI, 69.4%-94.5%; specificity, 78.8%; 95% CI, 75.3%-81.9%; AUC, 0.886; 95% CI, 0.827-0.944) had the highest discriminatory power between groups. Left adrenal gland width <0.39 cm was 80% (95% CI, 58.4%-91.9%) sensitive and 82.4% (95% CI, 74.2-88.4) specific for GDH. Serum cobalamin concentrations and ultrasonographic abnormalities of the GI tract were not different between groups. No single variable could be used to confidently rule out GDH and obviate the need for cortisol testing in dogs with a clinical presentation consistent with GDH.

Evaluation of the ACTH stimulation test using a low dose of a depot formulation in healthy dogs and in dogs with untreated Cushing's syndrome

The sensitivity of the adrenocorticotropic hormone (ACTH) stimulation test to detect Cushing's Syndrome (CS) using a depot formulation needs to be evaluated. The aims of this study were to propose a reference interval (RI) for cortisol values 1-hour after administration of a low-dose of depot ACTH in healthy dogs, and to evaluate the sensitivity of this test to detect CS, differentiating among types of CS based on ultrasound findings.Forty-one healthy dogs (20 males, 21 females) were prospectively included. Additionally, 90 dogs with CS (31 males, 59 females) were retrospectively included. Dogs with CS were ultrasonographically classified as follows: 44 dogs with symmetrical adrenomegaly consistent with pituitary-dependent hypercortisolism (PDH), 8 dogs with unilateral adrenomegaly and atrophy of the contralateral adrenal gland or unilateral or bilateral adrenomegaly with malignancy features consistent with adrenal-dependent hypercortisolism (ADH), 34 dogs with equivocal adrenal asymmetry (EAA) and 4 dogs with normal adrenal thickness.In healthy dogs, lower and upper limit of the 95% RI for 1-hour post-ACTH cortisol concentration and their 90% confidence intervals, were 4.4 (2.7–5.8) μg/dl and 18.4 (16.5–20.0) μg/dl, respectively. Post-ACTH cortisol concentration was above the RI in 90.0% (ci95%, 76.1–100) of dogs with CS. An elevated post-ACTH cortisol concentration was detected in 95.5% (ci95%, 76.1–100) of dogs with PDH, 62.5% (ci95%, 46.1–78.9) of dogs with ADH and 88.2% (ci95%, 69.1–100) of dogs with EAA. The sensitivity of the ACTH stimulation test using a low-dose of depot ACTH in high in dogs with CS.

Inverse relationship between eosinophil profiles and serum glucose concentration in dogs with naturally occurring hypercortisolism

Hyperglycemia and eosinopenia are well-known characteristics of hypercortisolism (HC) in humans, however, their association in dogs with HC has rarely been reported. This study aimed to evaluate the association between eosinophils and serum fasting glucose concentration in dogs with HC. Forty-seven dogs with HC and 43 dogs with non-adrenal illness were included. In this retrospective cohort study, the complete blood count, blood chemistry profile, and pre- and post-adrenocorticotropic hormone (ACTH) cortisol concentrations were analyzed. Significant differences were found in neutrophil, monocyte, eosinophil, and platelet counts; eosinophil percentage; neutrophil-to-lymphocyte ratio; aspartate aminotransferase, alanine aminotransferase, and gamma-glutamyl transferase activities (P < 0.05) between the groups. In dogs with HC, the eosinophil percentage was inversely correlated with fasting blood glucose (r = –0.3515, P = 0.0154) and post-ACTH cortisol concentrations (r = –0.6509, P < 0.0001). The neutrophil-to-lymphocyte ratio was inversely correlated with the eosinophil percentage (r = –0.4573, P = 0.0012) and count (r = –0.3688, P = 0.0108), but positively correlated with the fasting blood glucose level (r = 0.3888, P = 0.0069). Such correlations were not identified in dogs with non-adrenal illness. A multivariate analysis showed that only eosinophil percentage was associated with the presence of hyperglycemia in dogs with HC (odds ratio = 2.100, 95% confidence interval = 1.051–4.199, P = 0.0360). Therefore, eosinopenia induced by excess cortisol might be associated with altered glucose metabolism in dogs with HC. A better understanding of this correlation could be valuable to predict and prevent the complications of HC.

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

BackgroundResting 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/ObjectivesTo assess the cross‐sectional prevalence of hypoadrenocorticism in a group of dogs with chronic gastrointestinal signs presented to a referral internal medicine service.AnimalsTwo‐hundred and eighty‐two client‐owned dogs with chronic gastrointestinal signs and with resting cortisol concentration testing performed.MethodsRetrospective 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.ResultsResting 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 ImportanceAlthough 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.

Effect of topical florfenicol, terbinafine and mometasone furoate ear drops on adrenocortical function in healthy small breed dogs with bilateral otitis externa.

Testing for hyperadrenocorticism is commonly pursued in adult dogs with dermatological disease, and adrenocortical suppression has been well-documented following the use of topical corticosteroids in otic preparations. An otic suspension that contains florfenicol, terbinafine and mometasone furoate, and lasts for 30 days after a single application, frequently is used to treat canine otitis externa (OE). This medication was shown to cause adrenocortical suppression on Day (D)2 postadministration and two weeks after two applications two weeks apart. The objective of this study was to determine if topical florfenicol/terbinafine/mometasone furoate causes adrenocortical suppression in healthy, small-breed dogs with bilateral OE at D28 postapplication. Seven client-owned dogs weighing <10 kg diagnosed with non-Pseudomonas bilateral OE. Cortisol was measured pre- and post-adrenocorticotropic (ACTH) stimulation on D0. Topical florfenicol/terbinafine/mometasone furoate was applied in both ears. Dogs were reassessed on D28, and cortisol was measured pre- and post-ACTH stimulation. The median pre- and post-ACTH cortisol concentrations on D28 were 2.5 µg/dL (range 2.0-5.0 µg/dL) and 14.3 µg/dL (range 11.5-23.1 µg/dL), respectively. There was no significant difference (P = 0.85) between post-ACTH cortisol concentrations from D0 to D28. Results demonstrated no evidence of adrenocortical suppression, suggesting that there is no need to delay adrenocortical function testing in dogs treated with topical florfenicol/terbinafine/mometasone furoate when applied as per the manufacturer's recommendations.

Description and characterization of a hair coat disorder in schipperkes.

Schipperkes develop bilaterally symmetrical alopecia preceded by lightening of the hair coat not associated with systemic clinical signs. The alopecia is presumptively diagnosed as Alopecia X but has never been investigated. The purpose of this study was to describe clinical features, histopathological and laboratory abnormalities associated with symmetrical, noninflammatory alopecia in schipperkes. Three healthy and eight affected schipperkes. Complete blood count (CBC), serum chemistry panel, urinalysis (UA), urine cortisol: creatinine ratio (UCCR), total thyroxine (T4 ), free thyroxine by equilibrium dialysis (fT4 ed), thyroid stimulating hormone (TSH) and pre- and post-stimulation cortisol with sex hormone analyses were performed for all dogs. A minimum of two skin biopsy sites were sampled for histopathological evaluation. The CBC, serum chemistry panel, UA, T4 , fT4 ed, TSH and post-ACTH cortisol concentrations were normal for all dogs. Androstenedione concentrations were increased for all dogs; two of three healthy and five of eight affected dogs had increased post-ACTH androstenedione concentrations. Estradiol concentrations were increased for all healthy and four of eight affected dogs, with post-ACTH estradiol concentrations increased for all healthy and five of eight affected dogs. Progesterone concentrations were increased for two of three healthy and four of eight affected dogs. Post-ACTH progesterone concentrations were increased for one of three healthy and four of eight affected dogs. For one of three healthy and two of eight affected dogs, 17-hydroxyprogesterone concentrations were increased; post-ACTH 17-hydroxyprogesterone concentrations were increased in three of eight affected dogs only. Histopathology results from affected dogs were consistent with hair cycle arrest. This disorder resembles Alopecia X clinically and histologically.

Effects of Trilostane on urinary Catecholamines and their metabolites in dogs with Hypercortisolism

BackgroundGlucocorticoids influence the synthesis and metabolism of catecholamines (epinephrine and norepinephrine) and metanephrines (metanephrine and normetanephrine). The aim of this study was to measure urinary catecholamines and metanephrines in dogs with hypercortisolism before and during trilostane therapy.Urine samples were collected during initial work up and during therapy with trilostane in 14 dogs with hypercortisolism and in 25 healthy dogs. Epinephrine, norepinephrine, metanephrine and normetanephrine were measured using high-pressure liquid chromatography and expressed as ratios to urinary creatinine concentration.ResultsUntreated dogs with hypercortisolism had significantly higher epinephrine, norepinephrine, and normetanephrine:creatinine ratios compared to healthy dogs. During trilostane therapy, urinary catecholamines and their metabolites did not decrease significantly. However, dogs with low post-ACTH cortisol concentrations during trilostane therapy had less increased epinephrine, norepinephrine and normetanephrine:creatinine ratios compared to healthy dogs. There was no correlation of urinary catecholamines and their metabolites with baseline or post-ACTH cortisol or endogenous ACTH concentrations during trilostane therapy.ConclusionInfluences between steroid hormones and catecholamines seem to occur, as dogs with hypercortisolism have significantly higher urinary epinephrine, norepinephrine, and normetanephrine:creatinine ratios. Once-daily trilostane therapy does not lead to a significant decrease in catecholamines and their metabolites. Trilostane-treated dogs still have increased urinary epinephrine, norepinephrine and normetanephrine:creatinine ratios during trilostane therapy.

Clinical Relationship between Cholestatic Disease and Pituitary-Dependent Hyperadrenocorticism in Dogs: A Retrospective Case Series.

BackgroundA high prevalence of cholestatic disease, including gallbladder mucocele (GBM), has been reported in dogs with naturally occurring pituitary‐dependent hyperadrenocorticism (PDH).Hypothesis/ObjectivesDifferences exist in the clinical features of dogs with PDH and concurrent cholestatic disease, and also is the management of these dogs with trilostane.AnimalsSixty‐five client‐owned dogs with naturally occurring PDH.MethodsThis was a retrospective, observational case series. Each dog was treated with trilostane for at least 3 months before the study, and had a good clinical response, as determined by owners. Statistical comparisons of clinical signs, results of routine blood tests, basal and post‐ACTH cortisol concentration, and optimal trilostane dosage were made after dogs were separated into the following 3 groups by ultrasonographic imaging: normal on ultrasound (NOU) group, cholestasis group, and GBM group.ResultsThe GBM group had more severe clinical signs and significantly different total serum cholesterol concentration and post‐ACTH stimulation cortisol concentration at the time of diagnosis. Dogs that weighed <6 kg had a significantly higher prevalence of cholestatic disease than did the other dogs (P = .003). The optimal trilostane dosages for the GBM and cholestasis groups were 2.5 and 1.5 times the dosage of the NOU group, respectively (P < .001).Conclusions and Clinical ImportanceGallbladder disease associated with cholestatic disease is correlated with PDH in dogs, in both its clinical features and drug management. These findings may be associated with hypercholesterolemia, unidentified genetic factors, and the hydrophobic nature of trilostane.

Adrenal function in cats with cholestatic liver disease.

Cats with cholestatic liver disease experience significant morbidity and mortality when they undergo invasive procedures under anesthesia. Although inadequate adrenal response might account for these outcomes, adrenal function in cats with cholestatic liver disease has not been documented, to our knowledge. The goal of our study was to describe adrenal function in these cats. Twenty-seven cats with a serum bilirubin >230 µmol/L (3 mg/dL) and serum alanine aminotransferase >2 times the upper limit of normal had pre- and 60-min post-adrenocorticotropic hormone (ACTH) cortisol analysis after administration of 5 µg/kg cosyntropin intravenously. The change in cortisol concentrations (delta cortisol) was calculated. Pre- and post-ACTH cortisol concentrations were compared to reference values. Pre-ACTH, post-ACTH, and delta cortisol values were compared between cats surviving to discharge or for 30 d postdischarge. Mean pre-ACTH cortisol levels (205 ± 113 nmol/L [7.4 ± 4.2 µg/dL]) and post-ACTH cortisol levels (440 ± 113 nmol/L [15.9 ± 4.1 g/dL]) in cholestatic cats were significantly greater than reference values in clinically normal cats. There was no association of pre- or post-ACTH cortisol with survival. Cats with a delta cortisol <179 nmol/L (6.5 µg/dL) were more likely to be non-survivors at 30 d post-discharge ( p = 0.037) than cats with delta cortisol >179 nmol/L (6.5 µg/dL). Results indicate that cats with cholestasis have high basal and ACTH-stimulated cortisol values. A delta cortisol <179 nmol/L (6.5 µg/dL) defines a population of cats that have decreased 30-d survival.

Evaluation of Basal Serum or Plasma Cortisol Concentrations for the Diagnosis of Hypoadrenocorticism in Dogs.

BackgroundPrevious studies that included limited numbers of affected dogs have suggested basal cortisol concentrations ≤55 nmol/L (2 μg/dL) are sensitive, but nonspecific, for a diagnosis of hypoadrenocorticism. A detailed assessment of the diagnostic utility of basal cortisol concentrations is warranted.Hypothesis/ObjectivesTo evaluate the utility of basal cortisol concentrations for the diagnosis of hypoadrenocorticism in a large number of dogs, including those with and without serum electrolyte abnormalities.AnimalsFive hundred and twenty‐two dogs, including 163 dogs with hypoadrenocorticism, 351 dogs with nonadrenal gland illness, and 8 dogs with equivocal results.MethodsRetrospective study. Basal and post‐ACTH cortisol concentrations and sodium and potassium concentrations were collected from medical records. A receiver operating characteristic (ROC) curve was constructed for basal cortisol concentrations by standard methodologies. Sensitivity, specificity, and predictive values were determined for various cut‐points.ResultsThe area under the ROC curve was 0.988 and was similarly excellent regardless of serum electrolyte concentrations. At the most discriminatory cut‐point of 22 nmol/L (0.8 μg/dL), sensitivity and specificity were 96.9 and 95.7%, respectively. A basal cortisol concentration of ≤55 nmol/L (2 μg/dL) resulted in a sensitivity of 99.4%. Conversely, a basal cortisol concentration of ≤5.5 nmol/L (0.19 μg/dL) resulted in a specificity of 99.1%.Conclusions and Clinical ImportanceSimilar to findings in previous studies, basal cortisol concentrations >55 nmol/L (2 μg/dL) are useful in excluding a diagnosis of hypoadrenocorticism. Interestingly, excellent specificities and positive predictive values were observed at lower cut‐point cortisol concentrations.

Evaluation of 2 Trilostane Protocols for the Treatment of Canine Pituitary‐Dependent Hyperadrenocorticism: Twice Daily versus Once Daily

Trilostane is the drug of choice to treat pituitary-dependent hyperadrenocorticism (PDH) in dogs, but there is still controversy about which protocol best controls the clinical signs and results of adrenal functioning test. To compare the efficacy of twice daily (BID) versus once daily (SID) trilostane administration and to compare the safety of both protocols in the treatment of dogs with PDH. Thirty-two client-owned dogs diagnosed with PDH between 2008 and 2010 and treated with trilostane either BID or SID. In this prospective randomized study, 2 trilostane protocols were evaluated on the basis of the owner's perception of clinical signs, on the results of laboratory tests, and on the results of the ACTH stimulation test in dogs with PDH. Dogs were followed up for a period of 1 year. During the study, more dogs in the BID group had complete clinical recovery than in the SID group. However, there was no significant difference in the mean post-ACTH cortisol concentration between groups. Basal cortisol concentration at 6 months was higher in animals treated SID compared with animals treated BID. Mean total daily doses of trilostane used to control PDH, as well as adverse effects observed in the course of the study, in both groups were not statistically different. Adverse effects were mild using either protocol of treatment. Using trilostane BID might increase the number of dogs with a good clinical response compared with using trilostane SID.

DIAGNOSIS AND MANAGEMENT OF ATYPICAL HYPOADRENOCORTICISM IN A VARIABLE FLYING FOX (PTEROPUS HYPOMELANUS)

A 19-yr-old intact female variable flying fox (Pteropus hypomelanus) presented with lethargy, behavior changes, and substantial weight loss. Initial clinical pathology revealed hypoglycemia and reduced ionized serum calcium, and imaging, including computed tomography, did not lead to a diagnosis. An adrenocorticotropic hormone (ACTH) stimulation test revealed baseline and post-ACTH cortisol concentrations that were lower than reported normal baseline cortisol concentrations in this species. Treatment with prednisolone resolved the clinical signs and laboratory abnormalities. Repeated attempts to decrease the prednisolone dose caused recurrence of clinical signs and weight loss. Based on diagnostic test results and response to therapy, a diagnosis of atypical hypoadrenocorticism was made.

Method‐specific serum cortisol responses to the adrenocorticotrophin test: comparison of gas chromatography‐mass spectrometry and five automated immunoassays

The serum cortisol response to the adrenocorticotrophin (ACTH) test is known to vary significantly by assay, but lower reference limits (LRL) for this response have not been established by the reference gas chromatography-mass spectrometry (GC-MS) method or modern immunoassays. We aimed to compare the normal cortisol response to ACTH stimulation using GC-MS with five widely used immunoassays. An ACTH test (250μg iv ACTH1-24 ) was undertaken in 165 healthy volunteers (age, 20-66years; 105 women, 24 of whom were taking an oestrogen-containing oral contraceptive pill [OCP]). Serum cortisol was measured using GC-MS, Advia Centaur (Siemens), Architect (Abbott), Modular Analytics E170 (Roche), Immulite 2000 (Siemens) and Access (Beckman) automated immunoassays. The estimated LRL for the 30min cortisol response to ACTH was derived from the 2·5th percentile of log-transformed concentrations. The GC-MS-measured cortisol response was normally distributed in males but not females, with no significant gender difference in baseline or post-ACTH cortisol concentration. Immunoassays were positively biased relative to GC-MS, except in samples from women on the OCP, who showed a consistent negative bias. The LRL for cortisol was method-specific [GC-MS: 420nm; Architect: 430nm; Centaur: 446nm; Access 459nm; Immulite (2000) 474nm] and, for the E170, also gender-specific (female: 524nm; male 574nm). A separate LRL is necessary for women on the OCP. Normal cortisol responses to the ACTH test are influenced significantly by assay and oestrogen treatment. We recommend the use of separate reference limits in premenopausal women on the OCP and warn users that cortisol measurements in this subgroup are subject to assay interference.

Concentrations of Noncortisol Adrenal Steroids in Response to ACTH in Dogs with Adrenal‐Dependent Hyperadrenocorticism, Pituitary‐Dependent Hyperadrenocorticism, and Nonadrenal Illness

Increases of adrenal hormone concentrations other than cortisol have been reported in dogs with hyperadrenocorticism (HAC). Measuring noncortisol adrenal hormone concentrations will help identify HAC in dogs. The objective was to determine plasma cortisol, androstenedione, estradiol, progesterone, testosterone, and 17-hydroxyprogesterone concentrations during ACTH stimulation testing of dogs with clinical signs of HAC to ascertain their utility in diagnosis of the disease. Ninety dogs with clinical findings consistent with HAC had ACTH stimulation tests performed. Results from 29 dogs were excluded from analysis because diagnoses were inconclusive for a variety of reasons. Results from 32 dogs with HAC and 29 dogs with disease other than HAC were analyzed. Prospective observational study. Concentrations of adrenocortical hormones were determined before and 1 hour after injecting 5 μg/kg ACTH IM. Diagnoses were determined by response to therapy, histopathology or both. Post-ACTH cortisol (P < .001), progesterone (P = .001), and 17-hydroxyprogesterone (P < .001) concentrations were associated with a diagnosis of HAC. Sensitivity and specificity, respectively, for diagnosing HAC for post-ACTH cortisol were 84 and 59%, progesterone 88 and 55%, and 17-hydroxyprogesterone 91 and 59%, and for post-ACTH cortisol, progesterone and 17-hydroxyprogesterone combined were 88 and 55%. Of 5 dogs with HAC and normal post-ACTH cortisol concentrations, 5 had increased progesterone and 4 had increased 17-hydroxyprogesterone. Serum progesterone and 17-hydroxyprogesterone concentrations were useful to diagnose HAC in this study, but were not more sensitive or specific than cortisol concentration.

A comparison of once and twice daily administration of trilostane to dogs with hyperadrenocorticism

This retrospective study describes the use of trilostane given once versus twice daily in dogs with hyperadrenocorticism (SID vs. BID-group) in separate clinical trials. The groups were compared over a six month period using laboratory findings, dose required to suppress post-ACTH cortisol, and clinical scores from owner and clinician questionnaires. Ninety-three dogs enrolled the trials but for analysis of the final visit results only 56 dogs filled the inclusion criteria: 30 dogs in the SID-group and 26 dogs in the BID-group. Both treatment groups showed an improvement in clinical scores with time and no significant difference between them. In the BID-group post-ACTH cortisol concentrations went below 250 nmol/l sooner and in a higher proportion of dogs than in the SID-group. Twice-daily administration of trilostane also achieved a faster and more effective control for comparable daily doses. A higher individual tolerability (based on clinical scores) was found in the SID-group but there were no supporting laboratory findings. No dogs developed serious side-effects. This study reveals only small practical differences between once and twice daily trilostane administrations in treating hyperadrenocorticism. And the overall benefits of twice daily dosing have to be considered against the effect on the owners and their compliance with treatment.

Addison's disease due to bilateral adrenal malignancy in a dog

A 12-year-old Rottweiler cross Labrador was presented with anorexia and weakness. Adrenal insufficiency was diagnosed with hyponatraemia, hyperkalaemia and undetectable resting and post-ACTH cortisol and aldosterone concentrations. The only abnormal diagnostic imaging result was bilateral adrenomegaly. Cytologic findings of liver, spleen and peripheral lymph nodes were normal. The dog responded initially to standard replacement therapy but relapsed shortly afterwards. The owners opted for euthanasia and allowed only removal of both adrenal glands. Microscopically, infiltrative polymorphic proliferations of densely packed tumour cells arranged as nests, intermingled with multifocal areas of necrosis and inflammatory cells were found. Silver staining revealed a few non-neoplastic adrenomedullary cells, whereas neoplastic cells did not stain. Immunohistochemistry was negative for neuron-specific enolase, vimentin, cytokeratin, synaptophysin, chromogranin A, S-100 protein, CD 56, 79 and 3. The final diagnosis was highly anaplastic bilateral adrenal neoplasia. This is the first report of bilateral adrenal malignancy presenting as clinical hypoadrenocorticism in a dog.

Feed efficiency and body composition are related to cortisol response to adrenocorticotropin hormone and insulin-induced hypoglycemia in rams

Metabolic rate and energy consumption increase through the activation of the hypothalamic-pituitary-adrenal axis when an animal is exposed to a stressor. Residual feed intake (RFI) as a measure of efficiency has been shown to be related to exogenous adrenocorticotropin hormone (ACTH)-stimulated cortisol concentrations, which is indicative of the relationship between an animal's response to stress and the efficiency with which the energy is used for growth and production. In this study, we tested the hypothesis that sheep with low post-ACTH serum cortisol concentration relative to the other sheep in the flock have lower RFI values and lower cortisol concentrations following insulin-induced hypoglycemia. Adrenocorticotropin hormone (2.0 μg/kg body weight)-stimulated cortisol concentrations were measured in 100 sheep. The extreme responders were selected (n = 12 high cortisol, n = 12 low cortisol), and feed efficiency and body composition parameters were measured. A second ACTH challenge and an insulin challenge were administered. More efficient sheep (more negative RFI value) were found to have lower ( P < 0.05) cortisol concentrations following both an ACTH challenge and an insulin challenge. Low-cortisol sheep (low response to ACTH or insulin) were found to have a lower ( P < 0.05) proportion of fat tissue in comparison to the high-cortisol animals. These data clearly indicate that an animal's response to exogenous ACTH or insulin-induced hypoglycemia as a stressor is related ( P < 0.05) to efficiency of energy use when measured as RFI. These data have important implications in enabling identification of animals that are superior in terms of feed efficiency and for understanding the physiological mechanisms underlying efficiency of energy use.

Urinary Corticoid : Creatinine Ratios in Dogs with Pituitary‐Dependent Hypercortisolism during Trilostane Treatment

The adrenocorticotropic hormone (ACTH) stimulation test is used to evaluate trilostane treatment in dogs with hypercortisolism. The urinary corticoid : creatinine ratio (UCCR) is a good alternative to the ACTH stimulation test to determine optimal trilostane dose. Eighteen dogs with pituitary-dependent hypercortisolism. In this prospective study, the dose of trilostane was judged to be optimal on the basis of resolution of clinical signs of hypercortisolism and results of an ACTH stimulation test. The owners collected urine for determination of UCCR at 2-week intervals for at least 8 weeks after achieving the optimal trilostane dose. The UCCRs were significantly higher before treatment (11.5-202.0 x 10(-6); median, 42.0 x 10(-6)) than at rechecks 2 months after optimal dosing, but they did not decrease below the upper limit of the reference range in the majority of dogs. The UCCRs of 11 dogs that initially were dosed insufficiently (range, 7.5-79.0 x 10(-6); median, 31.0 x 10(-6)) did not differ significantly from UCCRs when the dosage was optimal (8.2-72.0 x 10(-6); median, 33.0 x 10(-6)). Post-ACTH cortisol concentrations did not correlate significantly with UCCRs at rechecks during trilostane treatment. Long-term follow-up indicated that the decrease in UCCR below the upper limit of the reference was associated with hypocortisolism. The UCCR cannot be used as an alternative to the ACTH stimulation test to determine the optimal dose of trilostane, but might be helpful in detecting dogs at risk for developing hypocortisolism during trilostane treatment.