Biochemical evaluation of adrenal dysfunction: the laboratory perspective.

In this study, we reviewed the diagnostic efficiency of laboratory tests that are performed for assessment of patients with Cushing's syndrome or adrenal insufficiency. Baseline laboratory data from patients subsequently diagnosed with adrenal dysfunction were analyzed for tests performed between 1987 and 1989 at our institution. Results were analyzed for 36 patients diagnosed with pituitary-dependent Cushing's syndrome, 15 with ectopic Cushing's syndrome, 12 with adrenal-dependent Cushing's syndrome, 20 with primary adrenal insufficiency, and 7 with secondary adrenal insufficiency. Tests reviewed were plasma cortisol, plasma corticotropin, urinary free cortisol, urinary 17-ketosteroids, urinary ketogenic steroids, low-dose and high-dose dexamethasone suppression, and metyrapone stimulation. Our findings suggest that a substantial proportion of diagnoses could be based on the results of three tests--plasma corticotropin, plasma cortisol, and urinary free cortisol. We present a nomogram that combines the results of plasma corticotropin and plasma cortisol testing to enhance the diagnostic efficiency of these tests.     

Salivary cortisol for the evaluation of Cushing's syndrome

Cortisol concentrations were measured in matched plasma and salivary samples from 8 healthy controls, 8 patients with Cushing's syndrome and 4 patients suspected of having spontaneous hypercortisolism. In healthy subjects, the circadian rhythm in salivary cortisol paralleled that in plasma. Absence of the diurnal rhythm in Cushing's syndrome was seen in saliva as well as in plasma. After ACTH stimulation, mean peak cortisol in saliva showed a 3-fold increase while in plasma there was a 2.5-fold increment above baseline. Cushing's syndrome, due to pituitary or adrenal adenoma was diagnosed equally well by measuring the cortisol response to cosyntropin in either plasma or saliva. Finally, the low- and high-dose dexamethasone suppression test was reflected equally well in both plasma and saliva. In patients suspected of having Cushing's syndrome dynamic tests can be performed in both plasma and saliva. However, in some samples, the salivary cortisol measurement appears advantageous over plasma cortisol determination.     

An evaluation of the distinction of ectopic and pituitary ACTH dependent Cushing's syndrome by clinical features, biochemical tests and radiological findings

The efficiency of various laboratory and radiological investigations in the differentiation of ectopic from pituitary dependent Cushing's syndrome was studied, based on findings in 23 patients with verified Cushing's disease and seven patients with the ectopic ACTH syndrome. Clinical features strongly favouring the ectopic type were male sex and history for less than 18 months. Basal biochemical features strongly indicating the ectopic syndrome included plasma K+ less than 3.0 mmol/l and HCO3 greater than 30 mmol/l; serum cortisol at 9 a.m. or midnight of greater than 800 nmol/l; urine free cortisol greater than 1300 nmol/24 hours; plasma ACTH greater than 100 ng/l. In the high-dose dexamethasone suppression test, suppression by less than 50 per cent of 9 a.m. serum cortisol, urine free cortisol or 17-oxogenic steroids was usually indicative of an ectopic source of ACTH. A mean suppressed value of greater than 450 nmol/l for the 9 a.m. and midnight cortisol combined occurred in all of those with the ectopic syndrome, but in none of the 23 patients with Cushing's disease. For urine free cortisol, a mean suppressed value of less than 1000 nmol/24 hours was found in all patients with Cushing's disease, but in none of those in the ectopic group. In the metyrapone test, there was an increase of less than or equal to 3-fold in 11-deoxycortisol at 24 hours in patients with ectopic ACTH; the increase was greater than 3-fold in all but one of the patients with Cushing's disease. Failure to respond to either dexamethasone or metyrapone was found in only one of the patients with Cushing's disease (Patient 16); in the ectopic group, all patients except Patient D failed to respond to either test. It is concluded that patients presenting with clinically obvious Cushing's syndrome along with measurable plasma ACTH can be reliably divided by conventional tests into those that are driven from the pituitary and those driven by ectopic ACTH.     

Direct assay of cortisol in human saliva by solid phase radioimmunoassay and its clinical applications

Direct determination of cortisol (F) in human saliva and its clinical applications were investigated. For this purpose, a solid phase radioimmunoassay (RIA) was carried out. The detection limits for F in 50 and 400 microliter of saliva were 0.125 and 0.0156 micrograms/100 ml, respectively, and the intra-assay coefficient of variation was 5.9--12.2%. Salivary F levels measured by this method were in good agreement with those by the RIA after extraction with dichlormethane reported previously. Salivary F levels were studied in 10 healthy adults with regard to diurnal rhythms, in rapid ACTH tests, and following intravenous injections of 20 mg F, and they showed almost similar changes to serum unbound F levels. Diurnal variations of salivary F in 8 normal children were nearly the same as those in healthy adults. In patients with Cushing's syndrome, neither normal diurnal rhythm of salivary F nor suppressed salivary F with dexamethasone were observed. Patients with adrenocortical insufficiency showed a lack of responsiveness in salivary F levels to stimulation with ACTH or lysin-vasopressin. These findings suggest that salivary F can be measured directly by the solid phase RIA and accurately reflects serum unbound F. The method is simple, accurate and useful for assessing adrenocortical function, especially in pediatric subjects and/or outpatients.     

Single determination of plasma ACTH using an immunoradiometric assay with high detectability differentiates between ACTH-dependent and -independent Cushing's syndrome

The purpose of this retrospective study was to elucidate the value of an ACTH assay with high detectability to differentiate between ACTH-dependent and -independent Cushing's syndrome. The study was based on the case records of 56 patients with Cushing's syndrome comprising 34 patients with ACTH-dependent Cushing's syndrome and 22 patients with ACTH-independent Cushing's syndrome. Basal morning plasma 1-39 ACTH was measured using an immunoradiometric assay (IRMA) with a normal range of 1.8-11 pmol/L. Peripheral corticotrophin-releasing hormone (CRH) tests were performed in 24 and 17 patients with ACTH-dependent and -independent Cushing's syndrome, respectively. Using a single ACTH measurement, a complete separation was observed between the two defined groups, with a cut-off value of 2.4 pmol/L. Mean ACTH concentration was 14.4 pmol L (range 2.5-47.7 pmol/L) in ACTH-dependent Cushing's syndrome and 0.6 pmol/L (range 0.2-2.2 pmol/L) in ACTH-independent Cushing's syndrome. The range of separation between the two groups was further increased by using two ACTH measurements in each patient or peripheral stimulation with CRH. It is concluded that in the majority of patients with Cushing's syndrome a single basal morning ACTH determination is sufficient to discriminate between ACTH-dependent and ACTH-independent Cushing's syndrome. In borderline cases with ACTH in the range 2-3 pmol/L, repeated measurements might be necessary. The peripheral CRH test was not superior to repeated ACTH measurements.     

Technical notes and clinical use of radioimmunologic determination of plasma ACTH]

Particular aspects of plasma ACTH radioimmunoassay are examinated. The results obtained with this method in adrenocortical diseases (Addison's disease, Cushing's syndrome, congenital adrenal hyperplasia) are reported and clinical value in etiological diagnosis of Cushing's syndrome is outlined. Moreover the results obtained in other syndromes of endocrinologic interest (massive obesity, Turner's and Klinefelter's syndromes, Laurence-Moon-Biedl syndrome, true precocious puberty, primary hypothyroidism, hypopituitary dwarphism) are reported and discussed.     

Normal and abnormal regulation of β-MSH in man

The regulation of plasma beta-melanocyte-stimulating hormone (beta-MSH) in man has been studied utilizing a radioimmunoassay previously described (1). In normal subjects plasma beta-MSH values ranged from 20 to 110 pg/ml. Metyrapone increased and dexamethasone decreased plasma beta-MSH levels. Surgical stress stimulated beta-MSH secretion. Plasma beta-MSH levels were elevated in patients with untreated Addison's disease and untreated congenital adrenal hyperplasia, and these levels fell to normal during glucocorticoid therapy. In patients with Cushing's syndrome due to pituitary adrenocorticotropic hormone (ACTH) excess, plasma beta-MSH was slightly elevated before treatment. In those patients who developed pituitary tumors and hyperpigmentation after bilateral adrenalectomy, plasma beta-MSH was greatly elevated. In patients with Cushing's syndrome due to adrenal tumor, plasma beta-MSH was subnormal. In patients with the ectopic ACTH syndrome, the levels of plasma beta-MSH were high. Plasma beta-MSH had a diurnal variation in normal subjects, patients with Addison's disease, and patients with congenital adrenal hyperplasia; but the normal diurnal variation was lost in patients with Cushing's disease. In patients with high plasma beta-MSH, simultaneous determinations of plasma ACTH showed close correlation between the degree of elevation of ACTH and that of beta-MSH. In extracts of tumors from patients with the ectopic ACTH-MSH syndrome the quantities of the two hormones were roughly equivalent. In patients with hyperpigmentation due to a variety of disorders other than pituitary-adrenal abnormalities, plasma beta-MSH was normal. It is concluded that the secretion of beta-MSH is regulated by the same factors that regulate ACTH.     

Stimulation of gonadal steroid synthesis by chronic excess of adrenocorticotropin in patients with adrenocortical insufficiency.

Analysis of 24-h urinary steroid excretion was performed by capillary gas chromatography in six patients (five men, one woman) with adrenocortical insufficiency. Ten healthy subjects (five men, five women) served as controls. A complete absence of all 21-hydroxylated steroid metabolites was seen in patients with adrenocortical insufficiency, whereas the excretion of several steroids lacking hydroxylation in the 21-position (pregnenolone, pregnenetriol, and 11-ketoandrosterone) was markedly increased. In addition, the presence of 11 beta-hydroxyandrosterone was confirmed by mass-spectrometry in the urine of three patients. This pattern of steroid excretion was unchanged in patients with adrenocortical insufficiency, both after stimulation by 1-24 adrenocorticotropin (ACTH) and after short-term (3-d) suppression with dexamethasone. We conclude that patients with adrenocortical insufficiency present a pattern of steroid excretion characterized by the absence of 21-hydroxylated metabolites. In the absence of functional adrenocortical tissue, long-term pathologically elevated concentrations of ACTH apparently stimulate early steps of steroid synthesis, most likely in the gonads. In addition, the presence of 11-hydroxylated steroid metabolites (11-ketoandrosterone, 11 beta-hydroxyandrosterone) in the urine of patients with adrenocortical insufficiency demonstrates that chronic ACTH excess in this disorder may induce some activity of 11 beta-hydroxylase, an enzyme not found in the gonads under physiological conditions.     

Corticotropin releasing factor as an aid in the diagnosis of Cushing syndrome

6 patients with Cushing's syndrome were investigated with regard to the effect of synthetic ovine corticotropin-releasing factor (o-CRF), administered as an intravenous bolus of 100 micrograms, on peripheral plasma concentrations of ACTH and cortisol. The purpose of this study was to evaluate the usefulness of this "CRF test" in the differential diagnosis of Cushing's syndrome as compared with conventional diagnostic procedures. 100 micrograms CRF caused a rise in plasma ACTH and cortisol in patients with bilateral adrenal hyperplasia (n = 3). However, in patients with cortisol-producing adrenal adenoma (n = 2) and ectopic ACTH overproduction (n = 1), no increase in plasma cortisol and ACTH was induced by exogenous CRF. We conclude from these findings that the CRF test will prove a valuable diagnostic tool to differentiate pituitary from extrapituitary forms of endogenous hypercortisolism in patients with Cushing's syndrome.     

Diagnosis and pathophysiology of Cushing's syndrome

Cushing's syndrome is the consequence of a sustained overproduction of cortisol (hydrocortisone) by the adrenal cortex. This may be due to excessive secretion of cortisol by functioning adrenocortical tumors or to "nontumorous" adrenocortical hyperfunction. The latter may be a result of stimulation of the adrenal cortex by increased release of corticotropin (ACTH) from a small pituitary tumor or from nonpituitary nonadrenal tumor. Carcinoids or carcinomas of the lung or pancreas, and even pheochromocytomas have caused the syndrome of ectopic ACTH production. The problems involved in the diagnosis of Cushing's syndrome are establishing its presence and determining the underlying cause. Treatment is then dependent upon the underlying pathogenetic lesion.     

Radioimmunoassay of ACTH in plasma

Techniques are described in detail for a radioimmunoassay of plasma adrenocorticotropin (ACTH) that is capable of detecting hormone in unextracted normal human plasma at 1:5 dilution under the conditions described. The sensitivity of the assay is at the level of 1 mumug/ml (equivalent to 0.014 mU/100 ml).In normal subjects ACTH concentrations averaged 22 mumug/ml (equivalent to 0.308 mU/100 ml) plasma at 8-10 a.m. In a smaller group the concentrations averaged 9.6 mumug/ml (equivalent to 0.134 mU/100 ml) at 10-11 p.m. Although a circadian rhythm in normal subjects was not always well marked throughout the daytime hours, plasma ACTH usually fell to its lowest value in the late evening. In hospital patients who were not acutely ill, concentrations were infrequently above 100 mumug/ml in the morning and usually fell to significantly lower levels in the late evening. Severely ill hospital patients occasionally exhibited a.m. concentrations above 200 mumug/ml.In a group of subjects showing frequent spiking of plasma 17-OHCS concentrations throughout the day parallel spiking of plasma ACTH as well was generally observed.Metyrapone produced marked increases in plasma ACTH within 24 hr in all cases and generally within 3-6 hr except when started late in the day. Dexamethasone brought about a persistent reduction in plasma ACTH in a patient under continued treatment with metyrapone.Hypoglycemia, electroshock, surgery under general anesthesia, histalog and vasopressin administration were usually followed by significant increases in plasma ACTH concentration. Prior administration of dexamethasone blocked the response to hypoglycemia.Marked elevations in plasma ACTH were observed in patients with adrenal insufficiency off steroid therapy, in Cushing's disease after adrenalectomy even in the presence of persistent hypercortisolemia, and in some untreated patients with Cushing's disease.Umbilical cord blood contained higher plasma ACTH concentrations than maternal blood at delivery in seven of eight cases.After suppression of ACTH secretion by dexamethasone or cortisol. ACTH disappeared from plasma with half-times ranging from 22 min to 30 min in three cases studied.     

原发性色素性结节状肾上腺皮质病的临床病理特征:附5例报道

目的:回顾性研究5例原发性色素性结节状肾上腺皮质病(PPNAD)的临床病理特征。方法:分析临床和实验室资料,对病变组织行HE染色和免疫组化标记。结果:本组5例患者临床诊断为库欣综合征,其中4例合并Carney综合征;1例为特发性。病理学表现为多发性色素性皮质结节伴结节间皮质萎缩;镜检观察到两种细胞,一种为含有嗜酸性细胞质和脂褐素的大细胞,另一种为细胞质富含脂质,空泡状。这些细胞免疫组化标记神经元特异性烯醇化酶阳性(++)。结论:PPNAD可造成促肾上腺皮质激素(ACTH)非依赖性皮质醇增多症。且多数患有Carney综合征。     

Cushing's syndrome. How to pinpoint and treat the underlying cause

In addition to prolonged glucocorticoid therapy (not discussed here), at least five other conditions cause Cushing's syndrome. They are excessive corticotropin secretion by the pituitary gland (which results in Cushing's disease), ectopic production of corticotropin by malignant nonpituitary tumors, benign adrenal adenoma, adrenal carcinoma, and primary adrenocortical nodular dysplasia. Each can be distinguished by a specific pathophysiologic process that triggers the adrenal glands to overproduce glucocorticoids. At present, diagnosis of Cushing's syndrome or disease relies heavily on the dexamethasone (Decadron, Hexadrol) suppression test. After diagnosis, other studies, including computed tomography, magnetic resonance imaging, and corticotropin radioimmunoassay, can be used to localize the site of the lesion. Treatment, of course, depends on the underlying cause.     

'Not Cushing's syndrome'.

Cushing's syndrome is characterized by protein wasting secondary to hypergluconeogenesis, which produces thin skin, poor muscle tone, osteoporosis and capillary fragility. These features distinguish patients with true Cushing's syndrome from those who have some of the clinical findings often associated with the syndrome, such as obesity, hypertension, striae and hirsutism. The dexamethasone suppression test helps identify patients with pseudo-Cushing's syndrome.     

An Evaluation of the Distinction of Ectopic and Pituitary ACTH Dependent Cushing's Syndrome by Clinical Features, Biochemical Tests and Radiological Findings

The efficiency of various laboratory and radiological investigationsin the differentiation of ectopic from pituitary dependent Cushing'ssyndrome was studied, based on findings in 23 patients withverified Cushing's disease and seven patients with the ectopicACTH syndrome. Clinical features strongly favouring the ectopic type were malesex and history for less than 18 months. Basal biochemical featuresstrongly indicating the ectopic syndrome included plasma K⁺<3.0 mmol/l and HCO₃ >30 mmol/l; serum cortisol at 9 a.m.or midnight of > 800 nmol/l; urine free cortisol > 1300nmol/24 hours; plasma ACTH > 100 ng/1. In the high-dose dexamethasone suppression test, suppressionby < 50 per cent of 9 a. m. serum cortisol, urine free cortisolor 17-oxogenic steroids was usually indicative of an ectopicsource of ACTH. A mean suppressed value of > 450nmol/l forthe 9 a.m. and midnight cortisol combined occurred in all ofthose with the ectopic syndrome, but in none of the 23 patientswith Cushing's disease. For urine free cortisol, a mean suppressedvalue of < 1000 nmol/24 hours was found in all patients withCushing's disease, but in none of those in the ectopic group. In the metyrapone test, there was an increase of     

Medical treatment for Cushing's syndrome

Systemic cortisol plays an important role in the metabolism of glucose, lipids and proteins, as well as in the regulation of electrolyte balance. It is well known that the development of the microvascular disease of various organs such as the heart and kidney, in patients with diabetes mellitus, hyperlipidemia and hypertension of which disorders are frequently associated with Cushing's syndrome. Thus, we should treat Cushing's syndrome as soon as possible, since many complications, including cardiovascular diseases and infections, will soon occur when the definite diagnosis is delayed. Adrenalectomy is essential for treatment for Cushing's syndrome even in the patients with pituitary or ectopic ACTH-producing tumor. Some case can not be treated with surgical procedures because of worsened conditions with several complications of infection and diabetes. Then we choose medical treatment. Medical adrenalectomy is achieved by using with mitotane which is usually used for adrenocortical cancer. We commonly treat the patients with Cushing's syndrome due to adrenal tumor and pituitary or ectopic ACTH producing tumor by using metyrapone which mainly inhibits 11-hydroxylase. Metyrapone is also recommended to treat the patients who are not well differentiated Cushing's disease from ectopic ACTH syndrome. We rarely use trilostane which is an inhibitor against 3beta-hydroxysteroid dehydrogenase (3beta-HSD). Replacement therapy with hydrocortisone should be considered if adrenal failure will occur during treatment with those drugs.     

Corticotropin-releasing hormone, proopiomelanocortin, and glucocorticoid receptor gene expression in adrenocorticotropin-producing tumors in vitro.

To differentiate between ectopic ACTH syndrome and Cushing's disease, gene expression of corticotropin-releasing hormone (CRH), proopiomelanocortin (POMC), and glucocorticoid receptor was examined in 10 pituitary adenomas (Cushing's disease) and in 10 ectopic ACTH-producing tumors. CRH increased plasma ACTH levels in all patients with Cushing's disease and in five patients with ectopic ACTH syndrome whose tumors contained CRH and CRH mRNA. In five CRH nonresponders, CRH was not detected in tumors that contained no CRH mRNA or that contained only long-size CRH mRNA. Dexamethasone (Dex) decreased plasma ACTH levels in all patients with Cushing's disease and in three patients with ectopic ACTH-producing bronchial carcinoid. These tumors contained glucocorticoid receptor mRNA. CRH increased and Dex decreased ACTH release and POMC mRNA levels in pituitary adenoma and bronchial carcinoid cells. PMA increased POMC mRNA levels only in carcinoid cells. These results reveal characteristics of ectopic ACTH-producing tumors: long-size CRH mRNA and PMA-induced POMC gene expression. In addition, there are two ectopic ACTH syndrome subtypes: tumors containing ACTH with CRH (CRH responder) and tumors without CRH. Dex decreases ACTH release and POMC mRNA levels in some bronchial carcinoids. Therefore, CRH and Dex tests have limited usefulness in differentiating between Cushing's disease and ectopic ACTH syndrome.     

原发性肾上腺皮质功能减退症20例临床分析

目的 探讨原发性肾上腺皮质功能减退症的临床特点及诊疗措施。方法 对20例原发性肾上腺皮质功能减退症患者的临床资料进行回顾性分析。结果 20例患者中13例为结核性，5例为特发性，2例为肾上腺切除术后；临床表现中以皮肤色素沉着较特异；非特异性症状出现早，且较常见。确诊有赖于皮质醇测定及快速促肾上腺皮质激素兴奋试验，其他激素及生化指标也有改变。结核性患者肾上腺CT以增生、钙化为主要表现。结论 确诊后给予泼尼松替代治疗，应激状态下应加大剂量，避免发生危象。     

Effect of ACTH on renal excretion of purine bases in a patient with isolated ACTH deficiency

We investigated the renal transport of purine bases (uric acid, hypoxanthine and xanthine) after rapid and continuous ACTH loading tests in a patient with isolated ACTH deficiency, a rare cause of secondary adrenocortical insufficiency. Plasma uric acid concentration and the urinary ratio of uric acid/creatinine did not change in the rapid ACTH test, which did not increase plasma cortisol concentration. In the continuous ACTH loading test, the plasma concentration of uric acid and oxypurines (hypoxanthine and xanthine) decreased, and the urinary excretion and fractional clearance of them increased as well as the plasma concentrations and urinary excretion of cortisol. These findings suggest that glucocorticoid directly affects the common renal transport pathway for uric acid, hypoxanthine, and xanthine.     

Parallel assays of beta-endorphin and ACTH in Cushing's patients undergoing petrosal sinus sampling

This study explores the possibility of improving endocrinologic testing during petrosal sinus catheterization by determining both beta-endorphin and corticotropin (ACTH). We studied 14 patients with Cushing's disease, two with adrenal tumor, and three with ectopic tumors secreting ACTH. In patients with Cushing's disease, beta-endorphin concentrations paralleled those of ACTH in all basal plasma samples collected either from petrosal sinuses or peripheral veins. Individual responses of beta-endorphin and ACTH to corticotropin releasing hormone (CRH) were closely related to the presence of a corticotroph adenoma. In such patients, a consistently higher concentration of beta-endorphin over ACTH was observed in all samples collected either from petrosal sinuses or peripheral veins; the ratios were unchanged after the administration of CRH. In patients with ectopic ACTH secretion, the mean ratio of beta-endorphin over ACTH (with both values expressed in pmol/L) was significantly higher (3.5) than that of patients with Cushing's disease (2.9) or Cushing's syndrome due to adrenal tumor (2.7).