Hypocholesterolaemia in hyperadrenal states.
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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 with the results from 12 dogs with confirmed pituitary-dependent hyperadrenocorticism (PDH). The post-ACTH cortisol concentration in the dogs with adrenocortical tumours ranged from 61 to 345-6 nmol/litre (median 251.5 nmol/litre) and they were within the reference range (150 to 450 nmol/litre) in five and unexpectedly low (< 150 nmol/litre) in three dogs. Both the basal and post-ACTH cortisol concentrations were significantly lower in the dogs with adrenocortical neoplasia than in the dogs with PDH. Eight hours after the LDDST, only two of six dogs with adrenocortical tumours had a cortisol concentration above 30 nmol/litre, and the median resting, three, and eight-hour cortisol concentrations were 31.5, 23.0, and 22.7 nmol/litre respectively. There was no significant cortisol suppression during the LDDST, although interpretation was complicated by the low cortisol concentrations, but two dogs showed a pattern of apparent suppression. Two dogs with adrenal tumours showed a diagnostically significant increase in 17-OH-progesterone concentration in response to ACTH although their cortisol concentrations did not increase greatly. These results differ from previous reports of the response of functional adrenal tumours to dynamic endocrine tests.
Hypothalamic norepinephrine (NE) and dopamine content was studied in dogs with spontaneous and iatrogenic hypercortisolism and in untreated normal dogs. The concentration of NE in the hypothalamus was subnormal in 4 of 8 dogs with pituitary-dependent hyperadrenocorticism (PDH), whereas long-term administration of corticotropin or cortisone acetate did not result in low hypothalamic NE content. In dogs with hyperadrenocorticism due to adrenocortical tumor subnormal as well as normal and high hypothalamic NE levels were found. Hypothalamic as well as striatal dopamine content did not differ among groups of dogs with PDH, adrenocortical tumor, corticotropin treatment, cortisone treatment and in untreated normal dogs. The subnormal hypothalamic NE levels in dogs with PDH may be involved in the hypersecretion of ACTH found in this disease. The normal hypothalamic dopamine levels in dogs with PDH are not consistent with a dopaminergic-depletion as the cause of PDH.
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Plasma aldosterone, cortisol, and renin activity were measured in nine recumbent patients with hyperaldosteronism, including seven with adenomas, one with idiopathic hyperplasia, and one with glucocorticoid suppressible hyperplasia. All had peak values of plasma aldosterone concentration from 3 a.m. to noon and lowest values at 6 p.m. or midnight. This rhythm was similar to the circadian pattern of plasma cortisol in the same patients. When these data were normalized to eliminate the wide variation in ranges of plasma aldosterone and cortisol between individuals, there was an excellent correlation (r = + 0.87, P < 0.005) between the two hormones. In contrast, plasma aldosterone concentrations did not correlate with plasma renin activity before or after normalization of data. Short term suppression of ACTH by administration of dexamethasone eliminated the circadian variation of plasma aldosterone in both patients with hyperplasia and in four of five patients with adenomas, while it markedly altered the rhythm in the fifth. Similar doses of dexamethasone were administered to four normal subjects and did not flatten the circadian rhythm of plasma aldosterone. These data suggest that patients with primary aldosteronism have a circadian rhythm of plasma aldosterone mediated by changes in ACTH.
Urinary free 11-hydroxycorticosteroid/creatinine ratios (UFC/Cr)were determined in early morning urine samples from 138 obese subjects attending endocrine clinics in the Glasgow area. The majority of patients (128) had UFC/Cr ratios within the normal range for non-obese subjects (5-55 mumol/mol). Of those with elevated UFC/Cr ratios, further investigations of the hypothalamic-pituitary-adrenal axis confirmed a diagnosis of Cushing's syndrome due to bilateral adrenal hyperplasia in six of the cases and adrenal tumours in a further two patients. In the remaining two patients there was evidence of intermittent adrenal hyperactivity with inconsistent responses to insulin-induced hypoglycaemia tests.
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Trabecular bone morphometry was done on rib samples of beagles with hyperadrenocorticism and adrenal adenomas to evaluate bone loss and the remodeling changes responsible. Beagles diagnosed as having clinical hyperadrenocorticism and those with milder or subclinical hyperadrenocorticism diagnosed on the basis of adrenal and pituitary lesions at necropsy had increased adrenal and pituitary gland weights. In a group of dogs with adrenal cortical adenomas there was atrophy of remaining cortex, and the combined weight of adrenal glands or pituitary weights were not increased. In dogs with clinical hyperadrenocorticism, mean trabecular bone volume was 25% less than controls (P = 0.10). In both clinical and subclinical hyperadrenocorticism groups, the extent of trabecular surface with unmineralized osteoid matrix and osteoblasts was significantly reduced. There were no changes in resorption surfaces or number of osteoclasts present. No bone changes were seen in dogs with adrenal adenomas. In dogs with hyperadrenocorticism it appeared that decreased bone formation was primarily responsible for the relative osteopenia that developed. Although parathyroid glands were moderately enlarged in those dogs for which weights were available, the bone changes were not those of increased remodeling expected in hyperparathyroidism.
Adrenal incidentalomas (AI) are not associated, by definition, with clinically evident syndromes; however, some AI patients may show biochemical indexes of subclinical hypercortisolism (SH). Previous data on female AI patients indicated that SH may lead to bone loss, at least at spine. No data are available on bone involvement in samples of only AI male patients. We measured bone metabolism and bone mineral density at spine and femur by dual-energy x-ray absorptiometry in 38 consecutive eugonadal male AI patients and 38 healthy matched control subjects. Patients were subdivided according to the presence or absence of SH (group SH+ and group SH-, respectively). Mean Z-score levels of spinal bone mineral density measured by dual-energy x-ray absorptiometry were lower (P < 0.05) in group SH+ (-0.42 +/- 1.62) in comparison with group SH- (0.6 +/- 1.13) and controls (0.47 +/- 1.06). Thus, in order for the most appropriate management to be individually tailored, bone mass evaluation is strongly indicated in AI male patients with SH, irrespective of their gonadal status.
Radiological characterization of an adrenal tumor as adenoma may decrease the need for follow-up imaging studies, biopsies, and unnecessary adrenalectomies. We retrospectively reviewed 299 adrenalectomies in 290 patients at Cleveland Clinic Foundation over a recent 5-yr period to assess the value of noncontrast Hounsfield units (HU) in characterizing whether an adrenal mass is adenoma or nonadenoma. The mean (+/- SD) HU value for the adrenocortical adenoma/hyperplasia group was 16.2 +/- 13.6 and significantly lower (P < 0.0001) than primary adrenocortical cancers (36.9 +/- 4.1), metastases (39.2 +/- 15.2), and pheochromocytomas (38.6 +/- 8.2). The sensitivity and specificity for 10- and 20-HU cutoff values to differentiate adenomas/hyperplasias from nonadenomas were 40.5 and 100% and 58.2 and 96.9%, respectively. The size of the adrenal tumor had less value with only 40.7 and 81.3% sensitivity and 94.7 and 61.4% specificity for 2- and 4-cm cutoff values. A combination of less than or equal to 4-cm adrenal mass size and noncontrast computed tomography HU less than or equal to 20 had 42.1% sensitivity and 100% specificity. Our study, the largest with surgical histopathology as the gold standard for diagnosis, supports a noncontrast computed tomography attenuation value of 10 HU as a safe cutoff value to differentiate adrenal adenomas/hyperplasias from nonadenomas.
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Extensive hormonal evaluation was performed in a girl with adrenal carcinoma during the primary tumor stage, following adrenalectomy, during the period when metastases were evident and while on treatment with o,p'-DDD. At the age of 14 months a diagnosis of congenital adrenal hyperplasia was made and treatment with dexamethasone (0.125 to 0.25 mg/day) resulted in a fall-off in growth rate, normal advancement in bone age, decrease in virilization and suppression of 17- ketosteroid excretion which continued until 4 3/12 years of age when virilization increased. At five years of age elevated serum and urinary androgen levels unsuppressible with dexamethasone were noted. Following removal of a large right adrenal carcinoma, serum and urinary hormone levels returned to normal. There months following surgery, liver metastases were documented associated with elevated levels of serum androgens. With o,p'-DDD treatment, serum dehydroepiandrosterone sulfate (DS) and urinary 17-ketosteroid (17-KS) excretion fell rapidly while there was a delay in the fall of free androgens. The persistence of free steroid secretion with decreased formation of DS suggests that the o,p'-DDD may have altered sulfatase activity before causing tumor necrosis and total decrease in steroidogenesis.
Plasma 18-hydroxycorticosterone (180HB) concentration was measured in 23 patients with primary aldosteronism. After overnight recumbency, the levels were markedly elevated and were 6 times higher in patients with aldosterone-producing adenomas than in patients with hyperplasia. A value of 100 ng/dl or greater at 0800 h after overnight recumbency distinguished an adenoma from hyperplasia. There was no overlap of values, as was observed with plasma aldosterone concentration (PAC) at 0800 h and after 4 h of upright posture at 1200 h. There was a significant negative correlation between the ratio of 180HB to PAC and the potassium concentration in patients with primary aldosteronism due to hyperplasia. Potassium repletion with potassium chloride and/or spironolactone in patients with aldosterone-producing adenomas decreased the 180HB:PAC ratio by decreasing 180HB and increasing PAC. 180HB is an effective discriminator of an adenoma and may be a useful marker of the events in late aldosterone synthesis.