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.     

Indications for study of adrenal function by measurement of the cortisol secretion rate]

Results of routine methods for measurements of plasma cortisol and his urinary metabolites have been comparated with those of cortisol secretion rate (CSR) measured by simple isotopic dilution; the latter appears for his specify and precision, to be the most suitable for an exact evaluation of cortisol production by the adrenals. In normal subjects CSR resulted slightly lower than those reported in the literature; in obese subjects CSR was slightly higher than in normals, also when it was related to the urinary creatinine. In the patients with Cushing's syndrome, CSR was considerably higher, with no overlap with the obese subjects. The CSR was also useful in showing values lower than normal, in hypopituitarism, and in confirming hormone abnormal findings in thyroid diseases.     

Cushing's Syndrome: AN EVALUATION OF THE CLINICAL USEFULNESS OF URINARY FREE CORTISOL AND OTHER URINARY STEROID MEASUREMENTS IN DIAGNOSIS

Urinary free cortisol excretion has been measured in a groupof 40 patients with Cushing's syndrome and in 34 patients inwhom this diagnosis was suspected on clinical grounds, but inwhom it was later disproved. Measurements were made in the basal state, during dexamethasonesuppression, and after metyrapone (when free cortisol and 11-deoxycortisolwere measured together) and the results compared with thoseof 17 oxogenic steroid measurements. In the basal state no normal or ‘suspected’ patientexcreted more than 106 µg/24 h of free cortisol whilethe lowest value seen in any patient with Cushing's syndromewas 110 µg/24 h. In 25 per cent of the patients with hyperadrenalism17 OGS excretion was within the normal range. Three patientswith ectopic ACTH produc tion all excreted more than 1000 µgof free cortisol in 24 h and in two of the three 17 OGS excretionwas greater than 100 mg/ h. During low-dose dexamethasone suppression (2 mg daily) freecortisol excretion fell to very low levels in normal and suspectedsubjects but failed to do so in patients with Cushing's syndrome,although a few patients did show suppression almost to withinthe normal range. In no patient with Cushing's syndrome did17 OGS excretion fall to less than 5 mg/24 h. However, it alsofailed to do this in 43 per cent of the ‘suspected’subjects. High-dose dexamethasone suppression (8 mg/day) failed to providea clear differentiation between patients with pituitary-dependentdisease and those with autonomous adrenal lesions or ACTH-producingtumours in terms of change in either free cortisol or 17 OGSexcretion. On metyrapone testing 96 per cent of pituitary-dependent patientsshowed a definite rise in 17 OGS excretion. We have not yetseen such a response in a patient with a non-pituitary-dependentlesion. Measurement of free F+S excretion was not ¹Present address: Department of Medicine, University Hospitalof South Manchester, Withington     

Measurement of urinary free 20 alpha-dihydrocortisol in biochemical diagnosis of chronic hypercorticoidism

Using liquid chromatography, we estimated the urinary excretion of 20 alpha-dihydrocortisol (20-DH) and urinary free cortisol (UFC) in normal subjects and in 40 patients with Cushing's syndrome of different etiologies. The median normal excretion rate (nmol/24 h) was 174 for 20-DH and 68 for UFC, the 20-DH/UFC ratio thus being 2.55. For patients with Cushing's syndrome, the excretion rate was 1798 for 20-DH and 298 for UFC, the ratio 6.03. We evaluated the effect of acute stimulation of adrenal secretion on 20-DH and UFC by administering corticotropin to six normal subjects. After such stimulation, the excretion rate was 566 for 20-DH and 1238 for UFC (ratio 0.45). Whereas 20-DH excretion rate exceeded the normal range in all patients, six patients had normal or even below-normal values for UFC excretion. Evidently, measurement of urinary 20-DH is a better test for chronic hypercorticoidism than is measurement of urinary UFC, and chronic hypercorticoidism can be differentiated from the acute state by the 20-DH/UFC ratio.     

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.     

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.     

Primary cortisol resistance associated with a thermolabile glucocorticoid receptor in a patient with fatigue as the only symptom.

We have studied a woman with an apparent receptor-mediated resistance to cortisol on the basis of elevated 24-h mean plasma cortisol levels and increased urinary free cortisol. Plasma ACTH concentrations were normal but she was resistant to adrenal suppression by dexamethasone. No stigmata of Cushing's syndrome were seen. To study the proposed end-organ resistance to cortisol, we examined the glucocorticoid receptor (GR) in lymphocytes and in fibroblasts from this patient and from her son. Several molecular properties of the GR of lymphocytes from the patient were indistinguishable from that of normal control subjects. In thermolability assays, however, the patient's GR as well as her son's GR showed a striking heat sensitivity at 40 degrees and 45 degrees C when compared with GR from normal persons. In addition, data from the thermolability assays correlated well with the lack at 45 degrees C of dexamethasone-induced decrease in in vitro [3H]thymidine incorporation into lymphocytes derived from both patients.     

Screening for Cushing's syndrome using early morning urine samples.

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.     

Evaluation of incidental renal and adrenal masses

Incidental renal or adrenal masses are sometimes found during imaging for problems unrelated to the kidneys and adrenal glands. Knowledgeable family physicians can reliably diagnose these masses, thereby avoiding unnecessary worry and procedures for their patients. A practical and cost-efficient means of evaluating renal lesions combines ultrasonography and computed tomographic scanning, with close communication between the family physician and the radiologist. Asymptomatic patients with simple renal cysts require no further evaluation. Patients with minimally complicated renal cysts can be followed radiographically. Magnetic resonance imaging is indicated in patients with indeterminate renal masses, and referral is required in patients with symptoms or solid masses. The need for referral of patients with adrenal masses is determined by careful assessment of clinical signs and symptoms, as well as the results of screening laboratory studies and appropriate radiologic studies. Referral is indicated for patients with incidental adrenal masses more than 6 cm in greatest diameter. Appropriate laboratory screening tests include the following: a 24-hour urinary free cortisol measurement for patients with evidence of Cushing's syndrome; a 24-hour urinary metanephrine, vanillylmandelic acid or catecholamine measurement for patients with evidence of pheochromocytoma; and a serum potassium level for patients with evidence of hyperaldosteronism.     

Decreased dehydroepiandrosterone sulfate in pigmented nodular adrenal dysplasia

Previous reports on patients with endogenous Cushing's syndrome describe low concentrations of the adrenal androgen dehydroepiandrosterone sulfate (DHEA-S) in adrenal adenoma and in a case of feminizing macronodular hyperplasia. Here we present hormonal data from two adult sisters with Cushing's syndrome as a result of pigmented nodular adrenal dysplasia. Corticotropin concentrations were in the mid-normal range, cortisol production was unaffected by administration of dexamethasone (8 mg/24 h), and baseline concentrations of DHEA-S were less than 0.5 mumol/L. A low concentration of DHEA-S in these and other previously reported patients with Cushing's syndrome correctly predicts the results of dynamic testing. Decreased DHEA-S in a patient with endogenous Cushing's syndrome can be ascertained by assay of a single sample and should prompt consideration of the diagnosis of autonomous bilateral nodular disease as well as adrenal adenoma.     

20-Dihydroisomers of cortisol and cortisone in human urine: excretion rates under different physiological conditions

The urinary excretion rates of free cortisol and cortisone as well as of their 20-dihydroisomers have been studied in normal subjects under different physiological or pharmacological conditions. For the estimation of steroid excretion rates, a fully automated, liquid-chromatographic method was used. In normal subjects, the median steroid excretion rates of free cortisol, cortisone, 20-alpha-dihydrocortisol, 20-beta-dihydrocortisol, 20-alpha-dihydrocortisone and 20-beta-dihydrocortisone were 6.7, 8.0, 9.8, 5.2, 5.7 and 1.3 mumol/mol creatinine. The excretion rates measured at three different intervals of the day followed a circadian rhythm similar to that known for the cortisol secreting activity of the adrenal gland. After adrenal stimulation by i.v. application of 250 micrograms of tetracosactide hexaacetate, (Synacthen, corticotropin beta 1-24) excretion of urinary cortisol was significantly higher than those of the other steroids. During a 24 h infusion of corticotropin beta 1-24, the excretion rates of cortisol and its C-20 reduced isomers increased to a significantly greater extent than those of cortisone and its C-20 reduced isomers. During a four-hour infusion of hydrocortisone, the relative increase of cortisol excretion was greater than that of the other steroids. During a five-hour infusion of metyrapone at different dosages, the excretion of all steroids decreased in a dose-dependent manner. The present data indicate that the 20-dihydroisomers of cortisol and cortisone in human urine primarily originate from the peripheral metabolism of cortisol rather than from adrenal secretion.(ABSTRACT TRUNCATED AT 250 WORDS)     

Primary cortisol resistance in man. A glucocorticoid receptor-mediated disease.

We have studied a man suspected of having primary cortisol resistance on the basis of high 24-h mean plasma cortisol levels (27.4 micrograms/dl) and no stigmata of Cushing's syndrome. His son had slightly elevated 24-h mean plasma cortisol levels (9.9 micrograms/dl; normal 7.52 micrograms/dl). Both had high plasma protein unbound cortisol and increased urinary free cortisol. Plasma ACTH concentration was high, and both were resistant to adrenal suppression by dexamethasone. The father appeared to have mineralocorticoid excess resulting in hypertension, hypokalemia, and metabolic alkalosis. This was found to be due to markedly elevated plasma levels of deoxycorticosterone and corticosterone. The son, who was normotensive, had mildly increased plasma corticosterone and normal deoxycorticosterone levels. To study the apparent end-organ resistance to cortisol, we examined the glucocorticoid receptor in the white cells and fibroblasts of these patients. In both tissues, using both whole cell and cytosol assays, the glucocorticoid receptor was found to have reduced affinity for dexamethasone. In the cytoxol assays, a reduced receptor number was found as well. We conclude that cortisol resistance is a rare familial syndrome owing to an abnormal glucocorticoid receptor with a decreased affinity for cortisol.     

Adrenal insufficiency in severe West Nile Virus infection

Objective To explore adrenal function in severe West Nile virus (WNV) infection.Design and setting Prospective interventional cohort study in a medical ICU of a teaching hospital.Patients Ten consecutive patients (seven men, mean age 64 ± 12 years, mean SAPS II 26 ± 6) with definite diagnosis of WNV related meningoencephalitis and variable proportion of organ/system failure. All patients had fever (mean body temperature 39 ± 1°C) and altered mental status (mean Glasgow Coma Score 11 ± 2). Mean SOFA score was 9 ± 2; eight patients had systemic inflammatory response syndrome, five septic shock, and six acute respiratory failure (usually from central origin) requiring mechanical ventilation.Interventions A short corticotropin test was performed in each patient to assess the adrenal function.Measurements and results Cortisol response was defined as the difference between baseline and corticotropin-stimulated peak. Absolute adrenal insufficiency was defined by a baseline cortisol level below 15 μg/dl (415 nmol/l). Relative insufficiency was defined by a cortisol response of 9 μg/dl (250 nmol/l) or less. Relative adrenal insufficiency, defined by a corticotropin response below 9 μg/dl, was observed in seven while the remaining three had normal cortisol response; six out of these seven died in the ICU. All patients with normal adrenal function survived.Conclusion Adrenal insufficiency is frequent in severe WNV infection and carries a poor outcome. In the absence of specific effective treatment, our data provide a rational to investigate a supplemental corticosteroid treatment in a controlled trial.     

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 unusual cause of Cushing's syndrome: primary pigmented nodular adrenal dysplasia

We report a case of Cushing's syndrome due to primary pigmented nodular adrenal dysplasia (PPNAD) and discuss the diagnostic process and management of this rare case. The diagnosis of PPNAD is discussed in the context of other causes of Cushing's syndrome. Eighty-five per cent of cases of Cushing's syndrome are due to a pituitary corticotrophic tumour (Cushing's disease). Rarer causes include cortisol secreting adrenal adenoma and ectopic ACTH secretion. In the routine investigation of Cushing's disease it is not unusual to find bilateral adrenal nodules on the CT scan. We present a case of Cushing's syndrome in which this radiographic finding was present and yet the biochemical diagnosis was one of ACTH independent disease. Histology revealed PPNAD.     

Cortisol levels in patients with severe community-acquired pneumonia

Objectives To evaluate cortisol levels and prevalence of adrenal insufficiency in patients with severe community-acquired pneumonia (CAP). Design and setting Retrospective cohort study in a 24-bed medical-surgical intensive care unit (ICU). Patients Forty patients with severe CAP admitted to the ICU from March 2003 and May 2005. Measurements and results Random cortisol levels were measured up to 72 h after ICU admission. A threshold of 20 μg/dl was considered for the diagnosis of adrenal insufficiency. Median cortisol levels were 15.5 μg/dl (IQR 10.8–25.1), and 26 patients (65%) met the criteria for adrenal insufficiency. Other cutoff levels of cortisol were evaluated, and 30 patients (75%) had cortisol levels below 25 μg/dl and 19 (47.5%) had cortisol levels below 15 μg/dl. When only patients with septic shock (n = 19) were evaluated, 12 (63%) had adrenal insufficiency. Conclusions Relative adrenal insufficiency occurs in a high proportion of patients with severe CAP. This finding highlights the importance of measuring cortisol levels and may help explain the potential benefits of hydrocortisone infusion in these patients.     

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.     

Cushing's disease: clinical manifestations and diagnostic evaluation

The most common endogenous cause of Cushing's syndrome is Cushing's disease. Frequent clinical findings include weight gain, truncal obesity, striae, hypertension, glucose intolerance and infections. Cranial nerve II may be affected by enlarging pituitary adenomas in Cushing's disease; cranial nerves III, IV and VI may also be affected. The evaluation of patients with suspected Cushing's disease and syndrome requires an understanding of the proper use and limitations of the tests commonly included in the diagnostic work-up. The best screening test for Cushing's syndrome is a 24-hour urine collection with analysis for urinary free cortisol excretion. Low-dose and high-dose dexamethasone suppression tests, corticotropin assays, a corticotropin-releasing hormone stimulation test and inferior petrosal sinus catheterization may be required for a definitive diagnosis. Magnetic resonance imaging is useful in localizing the lesion. Surgical removal of the lesion by a transphenoidal approach is usually successful, but long-term follow-up is required. Some patients require lifetime glucocorticoid replacement therapy.     

Simple methods for estimation of prednisone intake and metabolism

For patients treated with high doses of prednisone (over 40 mg/day) laboratory follow-up is important, particularly when the therapeutic response does not correlate with the dose of prednisone prescribed. Taking advantage of the similarity in structure of prednisone to cortisone and of prednisolone to cortisol we evaluated simple, inexpensive methods for the assessment of prednisone and prednisolone intake and bio-availability. Free urinary prednisolone was estimated by radioimmunoassay for cortisol and found to be linearly correlated with the dose of prednisone administered (r = 0.9310). Levels of free prednisolone were 6.5-11% of the dose of prednisone per day. Free and metabolized prednisone and prednisolone were estimated as 17-OHCS in the 24-hr urine collection. Total, conjugated and free 17-OHCS were linearly correlated with the dose of prednisone, the best correlation being with total 17-OHCS (r = 0.9060). About 40% of the prednisone administered was secreted as total 17-OHCS.     

Alcohol-induced Cushingoid syndrome.

A 35-year-old woman with alcoholic liver disease presented with physical stigmas and laboratory confirmation of Cushing's syndrome. With discontinuance of alcohol, her signs of Cushing's syndrome resolved and the urinary free cortisol and the urinary 17-hydroxycorticosteroid response to dexamethasone returned to normal. These findings broaden the spectrum of deranged glucocorticoid chemistry that can occur in alcohol-induced cushingoid syndrome.