Adrenal Function Tests Research Articles

RESTRAINT STRESS INDUCED CHANGES AND THEIR MODIFICATION BY SPIRULINA PLATENSIS IN ALBINO RATS: AN EXPERIMENTAL STUDY

RESTRAINT STRESS INDUCED CHANGES AND THEIR MODIFICATION BY SPIRULINA PLATENSIS IN ALBINO RATS: AN EXPERIMENTAL STUDY

Comparison of Adrenal Function Tests in Children - The Glucagon Stimulation Test Allows the Simultaneous Assessment of Adrenal Function and Growth Hormone Response in Children

The accurate assessment of adrenal function is necessary in many children with suspicion of pituitary insufficiency. The objective of this study was to evaluate the adrenal response during the glucagon stimulation test (GST) and its diagnostic utility in children. A total of 290 children, aged 10.1 +/- 5.0 years, were evaluated for adrenal function using the corticotrophin releasing hormone (CRH) test, the GST, and/or the insulin tolerance test (ITT). Glucagon stimulation provoked a substantial rise in cortisol and adrenocorticotropin (ACTH) that was independent of gender, age, or underlying growth hormone deficiency. There were no differences in peak cortisol levels in the GST compared to the CRH test in pair-wise intra-individual analyses in children with both tests performed within one year (615.4 +/- 30.5 vs 602.8 +/- 22.4 nmol/l, n=52). Similarly, there were no differences in the cortisol response between the ITT and CRH test. Peak cortisol levels in the CRH test correlated with the GST and the ITT. The magnitude of ACTH response, in contrast, was highest in the ITT with a 9.8-fold increase over baseline, while the increase in the GST (3.1-fold) and CRH test (1.6-fold) were more subtle. Since there is controversy concerning reliable cut-off values for adrenal function tests in children, we analyzed cut off levels in 186 children, including 26 children with adrenal insufficiency, using the CRH test. A peak cortisol level of 450 nmol/l provided the best balance of sensitivity (88.5%) and specificity (86.8%), while higher cut-off levels did not increase sensitivity but lost in specificity. In summary, the GST constitutes an1 equally sensitive test for the assessment of adrenal function in children that is not confounded by anthropometric parameters and is generally not accompanied by major side effects. It allows the simultaneous assessment of corticotroph and somatotroph function and may thus constitute a valuable alternative to the ITT.

The relative adrenal insufficiency syndrome in the intensive care unit: incidence and relationship to outcome

The aim of the current study was to investigate the incidence of relative adrenal insufficiency in a large cohort of critically ill patients. Furthermore, we wished to assess the relationship of adrenal function tests to outcome of patients admitted to an adult medical and surgical ICU. To this end, 151 (119 men) critically ill patients having various principal diagnoses were studied. The median age was 52 years (range 17–84 years). The median APACHE II score was 11. Blood was sampled within 48 hours of admission for measurement of serum concentrations of baseline cortisol and corticotropin (ACTH). Immediately after, a low-dose (1 μg) ACTH stimulation test was performed. Patients having stimulated cortisol levels below 18 μg/dl were defined as non-responders to the test. Median values for baseline cortisol and ACTH were 16.0 μg/dl (range 0.3–61.3 μg/dl) and 16.8 pg/ml (range 0.9–166.4 pg/ml) respectively. The median stimulated cortisol value was 22.4 μg/dl (range 4.7–70.0 μg/dl) and the median increment in cortisol was 7.1 μg/dl (range 0.2–25.6 μg/dl). There was a positive correlation between ACTH and baseline cortisol (r = 0.42, P < 0.001). Thirty-nine (26%) patients were non-responders to the low-dose ACTH stimulation test. Overall mortality was 26%. Non-survivors were older (64 vs 24 years, P = 0.002), and had a higher APACHE II score (13 vs 11, P = 0.007) compared with survivors. There were no differences between the two groups with regard to baseline or stimulated cortisol levels. Similarly, ACTH and the increment in cortisol was comparable in the two groups. In conclusion, this study involving a large number of severely ill patients showed that the relative adrenal insufficiency syndrome is quite common in the ICU; however, baseline or stimulated cortisol concentrations do not differ between survivors and non-survivors on admission to the ICU.

Adrenal failure followed by status epilepticus and hemolytic anemia in primary antiphospholipid syndrome

We report on a 14 year old boy who presented with the symptoms abdominal pain, fever and proteinuria. A hematoma in the region of the right pararenal space was diagnosed. Prothrombin time and activated partial thromboplastin time were prolonged, lupus anticoagulant and anticardiolipin antibodies were positive and serum cortisol was normal. Ten days after admission the boy suddenly suffered generalized seizures due to low serum sodium. As well, the patient developed hemolytic anemia, acute elevated liver enzymes, hematuria and increased proteinuria. At this time a second hemorrhage of the left adrenal gland was documented. Adrenal function tests revealed adrenal insufficiency. We suspected microthromboses in the adrenals and secondary bleeding and treated the boy with hydrocortisone, fludrocortisone and phenprocoumon.ConclusionAdrenal failure is a rare complication of APS in children with only five cases reported to date. As shown in our patient, this syndrome can manifest in a diverse set of simultaneously occurring symptoms.

Use of corticosteroid therapy in patients with sepsis and septic shock: An evidence-based review

In 2003, critical care and infectious disease experts representing 11 international organizations developed management guidelines for the use of corticosteroid therapy in patients with sepsis and septic shock that would be of practical use for the bedside clinician, under the auspices of the Surviving Sepsis Campaign, an international effort to increase awareness and improve outcome in severe sepsis. The process included a modified Delphi method, a consensus conference, several subsequent smaller meetings of subgroups and key individuals, teleconferences, and electronic-based discussion among subgroups and among the entire committee. The modified Delphi methodology used for grading recommendations built upon a 2001 publication sponsored by the International Sepsis Forum. We undertook a systematic review of the literature graded along five levels to create recommendation grades from A to E, with A being the highest grade. Pediatric considerations to contrast adult and pediatric management are in the article by Parker et al. on p. S591. Low doses of corticosteroids are recommended in patients with septic shock. In the absence of vasopressor requirement, corticosteroids should not be used to treat sepsis. High-dose corticosteroids are not recommended in severe sepsis. The use of adrenal function tests to guide decisions on corticosteroid therapy, the weaning of steroids at the end of the treatment period, the decision to discontinue steroids earlier with resolution of shock, and the addition of oral fludrocortisone are considered optional approaches.

Severe hyponatremia due to hypopituitarism with adrenal insufficiency: report on 28 cases

Objective: Severe hyponatremia due to hypopituitarism and adrenal insufficiency can be life-threatening, and treatment with glucocorticoids is very effective once the diagnosis of the underlying disorder has been made. In our experience, the diagnosis of hypopituitarism in hyponatremic patients is often overlooked. Methods: In a retrospective study we screened the files of 185 patients with severe hyponatremia (<130 mmol/l) that had been seen in one endocrinological unit of a university hospital between 1981 and 2001 in order to describe the clinical spectrum of patients with hyponatremia and hypopituitarism including secondary adrenal insufficiency. Results: In 139 cases it was possible to clearly ascribe the patients to the pathophysiological groups of (i) primary sodium deficiency, (ii) edematous disorders, and (iii) normovolemic disorders including the syndrome of inappropriate secretion of antidiuretic hormone (SIADH). Twenty-eight patients with severe ‘normovolemic hyponatremia’ (serum sodium: 116±7 mmol/l, mean±s.d.) had hypopituitarism and secondary adrenal insufficiency as shown by basal cortisol measurements and dynamic tests of adrenal function. In 25 cases of this group hypopituitarism (mostly due to empty sella, Sheehan's syndrome and pituitary tumors) had not been recognized previously, and in 12 cases recurrent hyponatremia during previous hospital admissions (up to four times) could be documented. The mean age of these patients (21 women, seven men) was 68 years. The most frequently occurring clinical signs were missing or scanty pubic and axillary hair, pale and doughy skin, and small testicles in the men. Frequent symptoms like nausea and vomiting, confusion, disorientation, somnolence or coma were similar to those in 91 patients with SIADH. Basal serum cortisol levels in the acutely ill state ranged from 20 to 439 nmol/l (mean±s.d.: 157±123), while in 30 other severely hyponatremic patients it ranged from 274 to 1732 nmol/l (732±351 nmol/l). In most patients with hyponatremic hypopituitarism, plasma antidiuretic hormone levels were inappropriately high, probably due to a failure of endogenous cortisol to suppress the hormone in a stressful situation. All patients recovered after low-dose hydrocortisone substitution. Most patients had other pituitary hormone deficiencies and were appropriately substituted subsequently. Conclusions: Hypopituitarism including secondary adrenal insufficiency seems to be a frequently overlooked cause of severe hyponatremia. A high level of suspicion is the best way to recognize the underlying disorder. Treatment with hydrocortisone is very effective.

Monitoring growth in asthmatic children treated with high dose inhaled glucocorticoids does not predict adrenal suppression

Aims: To determine whether routine outpatient monitoring of growth predicts adrenal suppression in prepubertal children treated with high dose inhaled glucocorticoid. Methods: Observational study of 35 prepubertal children (aged 4–10...

Behaviour and adrenal activity of first parturition and multiparous cows under a competitive situation

First parturition cows have to cope with several changes in their environment that can compromise their welfare and health. In addition to being separated from their calves they have to compete for eating and lying places with older and more experienced cows once they are introduced to the milking herd. The aim of this study was to compare the social and maintenance behaviour, and plasma cortisol levels after an adrenocorticotropic hormone (ACTH) challenge test of first parturition cows with those of adult cows. Thirty cows from the same herd, 15 in each group, were observed during 178 h in a cubicle building where social and maintenance behaviour was recorded. An adrenal function test was carried out after the observation period to determine cortisol levels in plasma before and after ACTH injection (−60, 0, 30, 60, 90, 120, and 210 min). First parturition cows spent more time walking and lying out of the cubicle during a 24-h period and during the night than adult cows ( P<0.05). Adult cows had on average a higher index of displacement than first lactation cows ( P<0.05). Cortisol levels at 60 and 90 min after injection of ACTH were lower in adult cows than in first parturition individuals ( P<0.05). In heifers, the proportion of time feeding during the day was negatively correlated with cortisol levels at 60 and 90 min after ACTH administration, and in multiparous cows the proportion of time lying out of the cubicles in a 24 h cycle and lying out during the night were positively correlated to cortisol levels at 60 min after ACTH administration. This information is useful to understand more about chronic stress in first lactation cows when introduced to a new herd and to make recommendations of management procedures to reduce welfare problems in these individuals.

Diagnosis of adrenal insufficiency.

The cosyntropin stimulation test is the initial endocrine evaluation of suspected primary or secondary adrenal insufficiency. To critically review the utility of the cosyntropin stimulation test for evaluating adrenal insufficiency. The MEDLINE database was searched from 1966 to 2002 for all English-language papers related to the diagnosis of adrenal insufficiency. Studies with fewer than 5 persons with primary or secondary adrenal insufficiency or with fewer than 10 persons as normal controls were excluded. For secondary adrenal insufficiency, only studies that stratified participants by integrated tests of adrenal function were included. Summary receiver-operating characteristic (ROC) curves were generated from all studies that provided sensitivity and specificity data for 250-microg and 1-microg cosyntropin tests; these curves were then compared by using area under the curve (AUC) methods. All estimated values are given with 95% CIs. At a specificity of 95%, sensitivities were 97%, 57%, and 61% for summary ROC curves in tests for primary adrenal insufficiency (250-microg cosyntropin test), secondary adrenal insufficiency (250-microg cosyntropin test), and secondary adrenal insufficiency (1-microg cosyntropin test), respectively. The area under the curve for primary adrenal insufficiency was significantly greater than the AUC for secondary adrenal insufficiency for the high-dose cosyntropin test (P < 0.001), but AUCs for the 250-microg and 1-microg cosyntropin tests did not differ significantly (P > 0.5) for secondary adrenal insufficiency. At a specificity of 95%, summary ROC analysis for the 250-microg cosyntropin test yielded a positive likelihood ratio of 11.5 (95% CI, 8.7 to 14.2) and a negative likelihood ratio of 0.45 (CI, 0.30 to 0.60) for the diagnosis of secondary adrenal insufficiency. Cortisol response to cosyntropin varies considerably among healthy persons. The cosyntropin test performs well in patients with primary adrenal insufficiency, but the lower sensitivity in patients with secondary adrenal insufficiency necessitates use of tests involving stimulation of the hypothalamus if the pretest probability is sufficiently high. The operating characteristics of the 250-microg and 1-microg cosyntropin tests are similar.

Severe hyponatremia due to hypopituitarism with adrenal insufficiency: report on 28 cases.

Severe hyponatremia due to hypopituitarism and adrenal insufficiency can be life-threatening, and treatment with glucocorticoids is very effective once the diagnosis of the underlying disorder has been made. In our experience, the diagnosis of hypopituitarism in hyponatremic patients is often overlooked. In a retrospective study we screened the files of 185 patients with severe hyponatremia (<130 mmol/l) that had been seen in one endocrinological unit of a university hospital between 1981 and 2001 in order to describe the clinical spectrum of patients with hyponatremia and hypopituitarism including secondary adrenal insufficiency. In 139 cases it was possible to clearly ascribe the patients to the pathophysiological groups of (i) primary sodium deficiency, (ii) edematous disorders, and (iii) normovolemic disorders including the "syndrome of inappropriate secretion of antidiuretic hormone" (SIADH). Twenty-eight patients with severe "normovolemic hyponatremia" (serum sodium: 116+/-7 mmol/l, mean+/-s.d.) had hypopituitarism and secondary adrenal insufficiency as shown by basal cortisol measurements and dynamic tests of adrenal function. In 25 cases of this group hypopituitarism (mostly due to empty sella, Sheehan's syndrome and pituitary tumors) had not been recognized previously, and in 12 cases recurrent hyponatremia during previous hospital admissions (up to four times) could be documented. The mean age of these patients (21 women, seven men) was 68 Years. The most frequently occurring clinical signs were missing or scanty pubic and axillary hair, pale and doughy skin, and small testicles in the men. Frequent symptoms like nausea and vomiting, confusion, disorientation, somnolence or coma were similar to those in 91 patients with SIADH. Basal serum cortisol levels in the acutely ill state ranged from 20 to 439 nmol/l (mean+/-s.d.: 157+/-123), while in 30 other severely hyponatremic patients it ranged from 274 to 1732 nmol/l (732+/-351 nmol/l). In most patients with hyponatremic hypopituitarism, plasma antidiuretic hormone levels were inappropriately high, probably due to a failure of endogenous cortisol to suppress the hormone in a stressful situation. All patients recovered after low-dose hydrocortisone substitution. Most patients had other pituitary hormone deficiencies and were appropriately substituted subsequently. Hypopituitarism including secondary adrenal insufficiency seems to be a frequently overlooked cause of severe hyponatremia. A high level of suspicion is the best way to recognize the underlying disorder. Treatment with hydrocortisone is very effective.

Adrenal Antibodies Detect Asymptomatic Autoimmune Adrenal Insufficiency in Young Women With Spontaneous Premature Ovarian Failure

Obstetrical & Gynecological Survey: March 2003 - Volume 58 - Issue 3 - p 180-181 doi: 10.1097/01.OGX.0000055758.75837.AE

Absence of urinary tract infection in dogs with experimentally induced hyperadrenocorticism

Objectives of this study were to determine occurrence of urinary tract infection and describe results of urine analysis and urine culture in dogs with experimentally induced hyperadrenocorticism. Dogs were randomly assigned to receive either hydrocortisone (nine dogs) or placebo (eight dogs) for 49 consecutive days. Before and on day 49 of treatment, evaluation of dogs included physical examination, abdominal ultrasound, urine culture, urinalysis, adrenal function testing, and measurement of urine protein and creatinine and activity of serum alkaline phosphatase. All dogs in the experimental group had clinical and laboratory findings of hyperadrenocorticism. Urine specific gravity was significantly decreased and urine protein-to-creatinine ratio was significantly increased in dogs with hyperadrenocorticism. Urinary tract infection did not occur in any dogs. We conclude that administration of hydrocortisone created a model of hyperadrenocorticism; however, urinary tract infection did not occur. Additional evaluation is needed to determine association between urinary tract infection and hyperadrenocorticism.

The clinical importance of adrenal insufficiency in acute hepatic dysfunction

Acute liver failure and septic shock share many clinical features, including hyperdynamic cardiovascular collapse. Adrenal insufficiency may result in a similar cardiovascular syndrome. In septic shock, adrenal insufficiency, defined using the short synacthen test (SST), is associated with hemodynamic instability and poor outcome. We examined the SST, a dynamic test of adrenal function, in 45 patients with acute hepatic dysfunction (AHD) and determined the association of these results with hemodynamic profile, severity of illness, and outcomes. Abnormal SSTs were common, occurring in 62% of patients. Those who required noradrenaline (NA) for blood pressure support had a significantly lower increment (median, 161 vs. 540 nmol/L; P < .001) following synacthen compared with patients who did not. Increment and peak were lower in patients who required ventilation for the management of encephalopathy (increment, 254 vs. 616 nmol/L, P < .01; peak, 533 vs. 1,002 nmol/L, P < .01). Increment was significantly lower in those who fulfilled liver transplant criteria compared with those who did not (121 vs. 356 nmol/L; P < .01). Patients who died or underwent liver transplantation had a lower increment (148 vs. 419 nmol/L) and peak (438 vs. 764 nmol/L) than those who survived ( P < .01). There was an inverse correlation between increment and severity of illness (Sequential Organ Failure Assessment, r = −0.63; P < .01). In conclusion, adrenal dysfunction assessed by the SST is common in AHD and may contribute to hemodynamic instability and mortality. It is more frequent in those with severe liver disease and correlates with severity of illness. (H EPATOLOGY 2002;36:395-402.)

Growth, Systemic Safety, and Efficacy During 1 Year of Asthma Treatment With Different Beclomethasone Dipropionate Formulations: An Open-Label, Randomized Comparison of Extrafine and Conventional Aerosols in Children

To assess the long-term safety of hydrofluoroalkane 134a (HFA)-beclomethasone dipropionate (BDP) extrafine aerosol administered by the Autohaler compared with chlorofluorocarbon (CFC)-BDP administered by a press-and-breathe metered-dose inhaler (pMDI) and spacer (+S) in the treatment of children with asthma. This 12-month, open-label, randomized, multicenter study enrolled 300 children who were aged 5 to 11 years and had well-controlled asthma on inhaled CFC-BDP or budesonide; 256 patients were using doses within the recommended range (200-400 microg) and were analyzed separately. Patients were randomized in a 1:3 ratio to continue on CFC-BDP+S at approximately the same dose as they were using before study entry or switch to HFA-BDP at half the daily dose. Asthma control was well maintained in the HFA-BDP group as evidenced by lung function tests and asthma symptoms compared with CFC-BDP+S at approximately twice the dose. There were no significant differences between the HFA-BDP 100 to 200 microg and CFC-BDP+S 200 to 400 microg treatment groups in mean change from baseline in height (5.23 cm vs 5.66 cm at month 12, respectively) or mean growth velocity from day 1 to month 12 (5.27 cm/y vs 5.71 cm/y, respectively). There were no significant differences between groups in adrenal function tests or markers of bone metabolism. In this long-term study in children with asthma, extrafine HFA-BDP provided long-term maintenance of asthma control at approximately half the dose compared with CFC-BDP+S. There were no clinically meaningful differences between HFA-BDP extrafine aerosol and conventional CFC-BDP+S with regard to growth or other systemic effects.

Use of aminoglutethimide in the treatment of pituitary-dependent hyperadrenocorticism in the dog.

The aim of this study was to evaluate the efficacy and safety of aminoglutethimide in the treatment of dogs with pituitary-dependent hyperadrenocorticism (PDH). Ten dogs were diagnosed with PDH based on clinical and laboratory data, adrenal function tests (adrenocorticotropic hormone [ACTH] stimulation test and urinary cortisol/creatinine ratio [UCCR] combined with a high dose oral dexamethasone suppression test) and ultrasonographic evaluation of the adrenal glands. Aminoglutethimide was administered daily at a dose of 15 mg/kg bodyweight for one month. Median basal cortisol concentration and post-ACTH cortisol concentration one month after treatment were significantly lower than pretreatment values. Complete response was achieved in one dog, and partial response was obtained in three dogs. Severe side effects of anorexia, vomiting and weakness occurred in one dog and medication was withdrawn. Two further dogs developed decompensations of concurrent diseases and medication was stopped in these animals as well. Mild toxicity occurred in four dogs. Moderate to severe elevations in liver enzymes occurred in all dogs. The efficacy of this drug is lower than that observed using mitotane and ketoconazole, and adverse effects limit its use. Aminoglutethimide, using the protocol described, cannot be recommended for long-term management of PDH in the dog.

Effects of Long‐Term Phenobarbital Treatment on the Thyroid and Adrenal Axis and Adrenal Function Tests in Dogs

Phenobarbital can interfere with the thyroid axis in human beings and rats by accelerating hepatic thyroxine metabolism because of enzyme induction. In human beings, it also can interfere with the low‐dose dexamethasone suppression test (LDDST) used to assess adrenal function by accelerating dexamethasone metabolism. This effect can cause a lack of suppression of pituitary ACTH and subsequent adrenal cortisol release after dexamethasone administration. The effects of phenobarbital on the thyroid axis, the adrenal axis, and adrenal function tests were prospectively investigated in 12 normal, adult dogs. Phenobarbital was administered at 5 mg per kilogram of body weight (range, 4.8–6.6 mg/kg) PO q12h for 29 weeks, resulting in therapeutic serum concentrations (20–40 μg/mL). Serum total thyroxine (TT4), free thyroxine (FT4) by equilibrium dialysis, total triiodothyronine (TT3), thyrotropin (TSH), and cholesterol were determined before and during phenobarbital treatment. LDDST, ACTH stimulation tests, and ultra‐sonographic evaluation of the adrenal glands were performed before and during treatment. TT4 and FT4 decreased significantly (P≤ .05), TT3 had minimal fluctuation, TSH had only a delayed compensatory increase, and cholesterol increased during phenobarbital treatment. The delayed increase in TSH, despite persistent hypothyroxinemia, suggests that accelerated hepatic thyroxine elimination may not be the only effect of phenobarbital on the thyroid axis. There was no significant effect of phenobarbital on either of the adrenal function tests. With the methods employed, we did not find any effects of the drug on the hormonal equilibrium of the adrenal axis.

Dose–response evaluation of the therapeutic index for inhaled budesonide in patients with mild-to-moderate asthma

PURPOSE: Inhaled corticosteroids have beneficial effects on pulmonary function and inflammation in patients with asthma, but they also cause systemic adverse effects, such as adrenal suppression. We evaluated the therapeutic index of inhaled corticosteroids in asthmatic patients by comparing their dose–response effects on lung function, surrogate markers of airway inflammation, and tests of adrenal function. SUBJECTS AND METHODS: After a 10-day placebo run-in, we evaluated the effects of 200 μg, 400 μg, and 800 μg of inhaled budesonide, each dose given twice daily sequentially for 3 weeks in 26 patients, aged 35 ± 12 years (mean ± SD), with mild-to-moderate asthma. Measurements were made of bronchial reactivity, exhaled nitric oxide (a marker of airway inflammation), spirometry, serum eosinophilic cationic protein concentration, and 10-hour overnight urinary cortisol excretion. Plasma cortisol levels were measured at 8 am and after stimulation with human corticotropin releasing factor. RESULTS: For measurements of pulmonary function and exhaled nitric oxide, there was a plateau in the mean response to budesonide between 400 μg (low dose) and 800 μg (medium dose) per day, whereas for eosinophilic cationic protein and bronchial challenge, maximal benefits occurred between 800 and 1,600 μg (high dose) per day. Effects on plasma cortisol levels showed maximal suppression at 1,600 μg of budesonide per day. The proportion of patients with an optimal therapeutic index, in terms of a good airway response (fourfold decrease in bronchial hyperreactivity) and minimal systemic response (overnight urinary cortisol greater than 20 nmol), was similar at low-dose (46%) and at high-dose (52%) budesonide. The proportion of patients with a suboptimal therapeutic index, a good airway response with a marked systemic response (overnight urinary cortisol greater than 20 nmol), increased from 4% at low dose to 38% at high dose. CONCLUSIONS: In patients with mild-to-moderate atopic asthma, there were dose-related effects of budesonide on surrogate markers of inflammation (bronchial hyperreactivity and serum eosinophilic cationic protein), although higher doses were associated with adrenal suppression and a decrease in the therapeutic index.

Effects of long-term phenobarbital treatment on the thyroid and adrenal axis and adrenal function tests in dogs.

Phenobarbital can interfere with the thyroid axis in human beings and rats by accelerating hepatic thyroxine metabolism because of enzyme induction. In human beings, it also can interfere with the low-dose dexamethasone suppression test (LDDST) used to assess adrenal function by accelerating dexamethasone metabolism. This effect can cause a lack of suppression of pituitary ACTH and subsequent adrenal cortisol release after dexamethasone administration. The effects of phenobarbital on the thyroid axis, the adrenal axis, and adrenal function tests were prospectively investigated in 12 normal, adult dogs. Phenobarbital was administered at 5 mg per kilogram of body weight (range, 4.8-6.6 mg/kg) PO q12h for 29 weeks, resulting in therapeutic serum concentrations (20-40 microg/mL). Serum total thyroxine (TT4), free thyroxine (FT4) by equilibrium dialysis, total triiodothyronine (TT3), thyrotropin (TSH), and cholesterol were determined before and during phenobarbital treatment. LDDST, ACTH stimulation tests, and ultrasonographic evaluation of the adrenal glands were performed before and during treatment. TT4 and FT4 decreased significantly (P < or = .05), TT3 had minimal fluctuation, TSH had only a delayed compensatory increase, and cholesterol increased during phenobarbital treatment. The delayed increase in TSH, despite persistent hypothyroxinemia, suggests that accelerated hepatic thyroxine elimination may not be the only effect of phenobarbital on the thyroid axis. There was no significant effect of phenobarbital on either of the adrenal function tests. With the methods employed, we did not find any effects of the drug on the hormonal equilibrium of the adrenal axis.

Effects of a 1% hydrocortisone conditioner on haematological and biochemical parameters, adrenal function testing and cutaneous reactivity to histamine in normal and pruritic dogs.

The purpose of this double-blinded study was to examine the effects of a 1% hydrocortisone, leave-on conditioner on haematological and biochemical parameters, adrenal function tests, and cutaneous reaction to serial dilutions of histamine phosphate in normal dogs and those with pruritic dermatitis. Groups 1 and 2 each consisted of eight normal dogs. Seven pruritic dogs comprised Group 3. All dogs were bathed twice weekly for 6 weeks. Groups 1 and 3 had 1% hydrocortisone conditioner applied after each bath. Group 2 had vehicle from the conditioner applied after each bath. The amount of 1% hydrocortisone applied to the treated dogs ranged from 278 to 416 mg/m2 . Haematological and biochemical analysis and adrenocorticotrophic hormone (ACTH) stimulation tests were performed on all dogs on days 0, 14, 28, and 42. Mean values for all blood and serum parameters remained within normal limits during the study. Post-ACTH cortisol levels were significantly lower in Group 3 compared to Groups 1 and 2 on day 42 (P < 0.05) and when averaged over all days of the study (P < 0.05 and P < 0.01, respectively). Serum alkaline phosphatase levels were significantly lower in Group 3 on day 0, compared to days 14 (P < 0.05), 28 (P < 0.01), and 42 (P = 0.05). All dogs received intradermal injections of buffered saline and five serial dilutions of histamine phosphate on days 0, 14, 28, and 42. No significant differences were apparent among the groups in subjective and objective evaluation of intradermally injected dilutions of histamine. In this study, the use of a 1% hydrocortisone leave-on conditioner did not result in clinically evident adverse effects, and only minor changes in blood parameters were detected. Although mean values in all groups remained within reference ranges throughout the study, the finding of statistically significant lower post-ACTH cortisol concentrations in the pruritic dogs (Group 3) suggests that absorption of hydrocortisone may have occurred. The results of this study also show that this product does not significantly suppress cutaneous reactivity to histamine in normal and pruritic dogs.

Dynamic adrenal function testing in eight dogs with hyperadrenocorticism associated with adrenocortical neoplasia

The results of adrenocorticotropin (ACTH) stimulation and low-dose dexamethasone suppression tests (LDDST) were evaluated retrospectively in eight dogs with clinical signs of hyperadrenocorticism arising from functional adrenocortical tumours, and compared...