The low-dose dexamethasone suppression test in patients with adrenal incidentalomas: comparisons with clinically euadrenal subjects and patients with Cushing's syndrome

Dexamethasone Suppression Testing in a Contemporary Cohort with Adrenal Incidentalomas in Two U.S. Integrated Healthcare Systems

Autonomous cortisol secretion (ACS) from an adrenal adenoma can increase the risk for comorbidities and mortality. The dexamethasone suppression test (DST) is the standard method to diagnose ACS. A multi-site, retrospective cohort of adults with diagnosed adrenal tumors was used to understand patient characteristics associated with DST completion and ACS. Time to DST completion was defined using the lab value and result date; follow-up time was from the adrenal adenoma diagnosis to the time of completion or censoring. ACS was defined by a DST > 1.8 µg/dL (50 nmol/L). The Cox proportional hazards regression model assessed associations between DST completion and patient characteristics. In patients completing a DST, a logistic regression model evaluated relationships between elevated ACS and covariates. We included 24,259 adults, with a mean age of 63.1 years, 48.1% obese, and 28.7% with a Charlson comorbidity index ≥ 4. Approximately 7% (n = 1768) completed a DST with a completion rate of 2.36 (95% CI 2.35, 2.37) per 100 person-years. Fully adjusted models reported that male sex and an increased Charlson comorbidity index were associated with a lower likelihood of DST completion. Current or former smoking status and an increased Charlson comorbidity index had higher odds of a DST > 1.8 μg/dL. In conclusion, clinical policies are needed to improve DST completion and the management of adrenal adenomas.

Steroidogenesis in patients with adrenal incidentalomas: Extended steroid profile measured by liquid chromatography-mass spectrometry after ACTH stimulation and dexamethasone suppression

OBJECTIVE

Describe the secretion and profile of adrenal steroids in patients with adrenal incidentalomas compared to control subjects.

DESIGN, SETTING AND PARTICIPANTS

A prospective study, 73 patients with adrenal incidentalomas, 21 bilateral and 52 unilateral and 34 matched controls in University Hospital.

METHODS

Collect fasting blood sample before and 60 min after ACTH test (250 µg IV). One week later, perform overnight 1 mg dexamethasone test. The following steroids were measured by liquid chromatography-mass spectrometry (LC-MS): pregnenolone, 17-OH pregnenolone, 17-OH progesterone, 11-deoxycorticosterone, 11-deoxyortisol, 21-deoxycortisol, corticosterone, cortisol, androstenedione and aldosterone.

RESULTS

Mean baseline serum cortisol was higher in incidentalomas, bilateral 361 ± 124, (range 143-665) nmol/L,(p < .0001), unilateral 268 ± 89 3.2 (range 98-507) nmol/L (p < .019) compared to controls 207 ± 100 (range 72-502) nmol/L. ACTH stimulation showed significantly higher levels in bilateral and unilateral cases compared to controls. After dexamethasone, mean serum cortisol levels suppressed in bilaterals 89 ± 69 (range 30-3) nmol/L (p < .0001), 58 ± 52 (range 16-323) nmol/L in unilateral (p < .01) compared to 26 ± 9 (range 7-46) nmol/L in controls. Mean baseline serum corticosterone was higher in bilateral 9.3 ± 4.8 (range 2.4-18.4) nmol/L (p < .005) and unilateral 7.3 ± 5.7 (range 0.1-30.3) nmol/L (p < .01) compared to controls 4.2 ± 2.4 (range 1.1-10.2) nmol/L, after ACTH stimulation significantly increased to higher levels in bilateral (p < .0002) and unilateral cases (p < .044) compared to controls. After dexamethasone, mean levels were 2.5 ± 2.6 (range 0.5-12.5) nmol/L in bilateral (p < .0006), 1.5 ± 1.6 (range 0.3-9.3) nmol/L in unilateral (p < .09) and 0.75 ± 0.46 (range 0.1-2.1) nmol/L in controls. Mean baseline serum 11-deoxycorticosterone (DOC) was higher in bilaterals 0.32 ± 0.23 (range 0.08-1.1) nmol/L (p < .03) compared to controls 0.15 ± 0.21 (range 0.08-1.1) nmol/L. ACTH stimulation increased levels to 3.27 ± 1.72 (range 0.5-7.4) nmol/L in bilateral cases compared to controls 1.369 ± 1.53 (range 0.1-7.1) nmol/L (p < .0001). Dexamethasone decreased levels to baseline (p ns). There were significant differences in serum 21-deoxycortisol (p < .0002) and serum pregnenolone (p < .004) only after ACTH stimulation.

CONCLUSIONS

There is increased activity in several steroid biosynthesis pathways and higher steroid levels in bilateral compared to unilateral cases and evidence of hypercortisolism in 30% unilateral and 62% of bilateral incidentalomas.

Accuracy of Laboratory Tests for the Diagnosis of Cushing Syndrome

CONTEXT

The diagnosis of Cushing syndrome (CS) can be challenging. It remains to be determined which diagnostic tests are the most accurate.

OBJECTIVE

To summarize the accuracy of diagnostic tests for CS using contemporary meta-analytic techniques (hierarchical models).

DATA SOURCES

PubMed, Embase, Scopus, Web of Science, and the Cochrane Database of Systemic Reviews (inception until August 3, 2018).

STUDY SELECTION

Studies performed in adults that determined the accuracy of one or more diagnostic tests: overnight 1-mg dexamethasone suppression test (DST), 2-day low-dose DST (2d DST), 24-hour urinary free cortisol (UFC), late-night salivary cortisol (LNSC), midnight serum cortisol (MSC), and the dexamethasone-suppressed CRH (dex-CRH) and desmopressin (dex-DDAVP) tests.

DATA EXTRACTION

Two authors independently extracted data and performed methodological assessments.

DATA SYNTHESIS

One hundred thirty-nine studies (14 140 participants) were included in the analysis. The respective sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio (95% confidence interval [CI]) estimates include the following: DST 98.6% (96.9%-99.4%), 90.6% (86.4%-93.6%), 10.5 (7.2-15.3), and 0.016 (0.007-0.035); 2d DST 95.3% (91.3%-97.5%), 92.8% (85.7%-96.5%), 13.2 (6.47-27.1), and 0.051 (0.027-0.095); UFC 94.0% (91.6%-95.7%), 93.0% (89.0%-95.5%), 13.3 (8.47-21.0), and 0.065 (0.046-0.092); LNSC 95.8% (93.%-97.2%), 93.4% (90.7%-95.4%), 14.6 (10.3-20.7), and 0.045 (0.030-0.066); MSC 96.1% (93.5%-97.6%), 93.2% (88.1%-96.3%), 14.2 (7.96-25.2), and 0.042 (0.026-0.069); and dex-CRH 98.6% (90.4%-99.8%), 85.9% (67.6%-94.7%), 7.0 (2.80-17.6), and 0.016 (0.002-0.118). A single study evaluated dex-DDAVP. Meta-regression and a novel network meta-analytic approach suggest that DST is the most sensitive while UFC is the least sensitive.

CONCLUSIONS

All of the included diagnostic tests for CS are highly sensitive and specific. It appears that the DST is the most sensitive while the UFC is less sensitive. The specificity of all first-line tests appears comparable.

Autonomous cortisol secretion in adrenal incidentalomas

Adrenal incidentalomas (AI) are one of the most frequent reasons for consultation in Endocrinology, as they are present in 3-10% of the general population. Up to 20% of them may have autonomous cortisol secretion (ACS), a term that refers to AI carriers with biochemical evidence of excess cortisol, but without the "specific" clinical signs of Cushing's syndrome. As ACS is associated with an increased risk of diabetes, obesity, high blood pressure (HBP), osteoporosis, cardiovascular events, and global mortality; its correct identification is of great importance. There are different laboratory assays to detect ACS, but all of them have some limitations. The dexamethasone suppression test is the most accepted for screening. However, there is no consensus on the cutoff point that should be used. Low levels of ACTH and DHEA-S and high urinary free cortisol are also associated with ACS, but in isolation they are of little value to establish the diagnosis. Considering its clinical implications and the lack of consensus in the diagnosis and in which is the most appropriate management of these patients, this review offers a quick reference guide of ACS, presenting an exhaustive review of the topic: its definition, epidemiology, diagnosis, clinical implications, treatment, and follow-up.

Does IGF-1 play a role in the etiopathogenesis of non-functioning adrenocortical adenoma?

PURPOSE

The aim of this study was to investigate the possible association of insulin-like growth factor-1 (IGF-1) with the pathogenesis of non-functioning adrenocortical adenomas (NFAs).

METHODS

This study included 50 female patients (mean age 54 years) with NFAs, 55 patients (mean age 48 years; 20 male, 35 female) with acromegaly and 38 female control subjects (mean age 58 years). Body mass index (BMI) and waist circumference (WC) of the subjects were recorded and blood samples for IGF-1 were taken. Insulin resistance was calculated using the homeostatic model assessment (HOMA) score. Since most of the acromegaly patients had been using medicine that could have effected insulin resistance, HOMA scores were calculated only in patients with NFAs and the controls. Computerized tomography or magnetic resonance imaging was taken of the acromegalics and controls to detect adrenal mass frequency.

RESULTS

The mean age was similar among the groups. As expected, the serum IGF-1 levels were significantly higher in patients with acromegaly than in patients with NFAs and the controls (p < 0.001). Although BMI, WC, and serum IGF-1 levels were significantly higher (p < 0.001) in patients with NFAs, the HOMA scores were similar between patients with NFAs and control groups. Although none of the control subjects had adrenal masses, NFAs were detected in 14 (25%) out of 55 acromegalic patients.

CONCLUSIONS

Higher serum IGF-1 levels in patients with NFAs compared to the control group and an increased prevalence of NFAs in acromegaly patients compared to control subjects and the general population suggest an association of IGF-1 with the etiopathogenesis of NFA.

Adrenal incidentaloma: evaluation and management

Adrenal incidentalomas are adrenal masses discovered incidental to imaging studies performed for reasons unrelated to adrenal pathology. Although most adrenal incidentalomas are non-functioning benign adenomas, their increasing prevalence presents diagnostic and therapeutic challenges. The assessment of adrenal incidentalomas is aimed at deciding whether or not the tumour should be surgically removed. Adrenalectomy is indicated for phaeochromocytoma, other symptomatic hormone-secreting tumours and those with a high risk of malignancy. Biochemical screening for tumour hypersecretion is mandatory in all adrenal incidentalomas, since hormone secreting tumours may be clinically silent. The diagnosis of phaeochromocytoma is of paramount importance because of its life-threatening complications. Non-functioning adrenal incidentalomas need assessment for risk of malignancy, and this is based on the size of the tumour and its imaging characteristics. An observational policy with periodic radiological and biochemical reassessment is pursued in patients with non-functioning incidentalomas with low malignancy risk. The duration and frequency of reassessment remains unclear, as the natural history of adrenal incidentalomas has yet to be clearly defined, and there is a lack of controlled studies comparing surgical intervention with observation. However, the possibility of acquiring autonomous hypersecretion or conversion to malignancy in an incidentaloma diagnosed to be a benign non-functioning lesion is very low, and most patients may be safely discharged after an initial follow-up period of 2 years.

Primary aldosteronism in hypertensive patients: clinical implications and target therapy

BACKGROUND

The prevalence of primary aldosteronism (PA) in hypertensive patients varies according to diagnostic testing and ascertained normal cut-offs. The aim of this case-control study was to confirm the high prevalence of PA in a large hypertensive population and evaluate the antihypertensive effect of mineralocorticoid receptor antagonists (MRA) treatment.

MATERIAL AND METHODS

We investigated 327 hypertensive and 90 matched normotensive subjects with normal adrenal imaging. Serum aldosterone (ALD), active renin (REN) levels and aldosterone/active renin (ALD/REN) ratio were measured before and after a combined sodium chloride, fludrocortisone and dexamethasone suppression test (FDST). Post-FDST values were compared to cut-offs obtained from controls (post-FDST ALD 2·96 ng/dL and post-FDST ALD/REN 0·93 ng/dL/μU/mL). PA patients received MRA treatment.

RESULTS

By applying the combination of post-FDST ALD levels and ALD/REN ratio, 28·7% of the hypertensive patients had PA. There was a positive, albeit weak, correlation between systolic (SBP) and diastolic blood pressure (DBP) and ALD levels and/or ALD/REN ratio after the FDST (P < 0·0001). SBP was associated with a post-FDST ALD of 3·24 ng/dL and ALD/REN ratio of 0·90 ng/dL/μU/mL, whereas post-FDST ALD had an inverse association at serum K+ values of less than 3·9 mEq/L. MRA treatment in 69 PA patients, resulted in a significant reduction in the maximum SBP and DBP values (28 ± 15 and 14 ± 7 mmHg, respectively, P < 0·0001).

CONCLUSIONS

Using the FDST, an increased prevalence of PA in hypertensives was observed. Α significant blood pressure lowering effect was obtained with MRA treatment, implying that these agents may be beneficial in a significant number of hypertensive patients.

Cortisol secretion from adrenal adenomas discovered as incidentalomas is responsive to ACTH

OBJECTIVE

Adrenal adenomas discovered as incidentalomas may secrete cortisol and cause subclinical hypercortisolism. This cortisol secretion is considered to be autonomous. The aim was to investigate whether cortisol secretion by adenomas is responsive to ACTH.

DESIGN

Descriptive retrospective study of consecutive patients.

PATIENTS

Eighty patients found to have adrenal incidentalomas during 2008 and 2009 at our hospital were examined, and 50 patients with a unilateral adenoma were included in the study.

MEASUREMENTS

Cortisol and ACTH were measured at baseline and using 1-mg overnight dexamethasone suppression test (DST). The cortisol response to ACTH was calculated using the expression: (cortisolbasal -cortisolDST )/(ACTHbasal -ACTHDST ).

RESULTS

The patients were divided into three groups according to their basal ACTH: ≥3·0 pm (29 patients), 2·0-2·9 pm (9 patients) and <2·0 pm (12 patients). Cortisol at DST was similar in the three groups: 30, 46 and 43 nm (P = 0·10). The cortisol response to ACTH increased stepwise between the groups: 98, 172 and 249 nm/pm (P = 0·000, undetectable ACTH was set to 0 pm). Basal ACTH was negatively correlated with the size of the adenoma and positively correlated with the attenuation of the adenoma at unenhanced CT (P = 0·03 and P = 0·04, respectively).

CONCLUSIONS

Patients with adrenal adenomas and low basal ACTH show increased cortisol response to ACTH, and the adenomas seem to be the source of the increased cortisol secretion. The increased response to ACTH could be a pathogenic factor in metabolic complications of subclinical hypercortisolism. The cortisol response to ACTH may therefore be a useful measure of subclinical hypercortisolism.

Glucocorticoid receptor and molecular chaperones in the pathogenesis of adrenal incidentalomas: potential role of reduced sensitivity to glucocorticoids

Glucocorticoid (GC) sensitivity depends on glucocorticoid receptor (GR) and heat shock proteins (Hsps). We investigated whether common GR genes (ER22/23EK, N363S, Bcl I, and 9β) and adrenocorticotropin receptor promoter polymorphisms influence susceptibility for unilateral adrenal incidentaloma (AI), plus GR and Hsp expression in tumorous (n = 19), peritumorous (n = 13) and normal adrenocortical (n = 11) tissues. Patients (n = 112), population-matched controls (n = 100) and tumor tissues (n = 32) were genotyped for these polymorphisms. Postdexamethasone serum cortisol was higher in patients (p < 0.001). GR gene variants, larger allele of Bcl I (odds ratio [OR] 2.9; 95% confidence interval [CI] 1.7-5.1; p < 0.001] and minor allele of 9β (OR 3.0; 95% CI 1.6-5.7; p < 0.001) were independent predictors of AI. In patients, the first allele is linked with larger tumors (p = 0.002) and the latter with higher postdexamethasone cortisol levels (p = 0.025). Both allele carriers had lesser waist circumference (p = 0.02), similar adrenocorticotropin and higher basal (p = 0.024) and postdexamethasone cortisol concentrations (p < 0.001). Tumorous and constitutional genotypes were similar. GR-D is the major receptor isoform in normal adrenal cortex by Western blotting. Loss of other receptor isoforms, decrease in immunostaining for GR (p < 0.0001), underexpression of chaperones (p ≤ 0.01) and the presence of inducible Hsp70 were found in adenomas. In conclusion, GR gene variants, C allele of Bcl I and minor allele of 9β, are associated with AIs. Their concurrent presence in patients reduces GC sensitivity. Normal adrenal cortex preferentially expresses GR-D. In adenomas, the lack of other GR isoforms and underexpression of heat shock proteins perhaps permanently impair GC signaling, which could promote dysregulated cortisol production and tumor growth. The innate GC sensitivity probably modifies these effects.

Subclinical hypercortisolism and CT appearance in adrenal incidentalomas: a multicenter study from Southern Sweden

Evaluation of subclinical hypercortisolism (SH) in patients with adrenal incidentaloma (AI) including its correlation to size, attenuation at unenhanced computed tomography (CT) and unilateral or bilateral adrenal disease. Nine hospitals in Southern Sweden investigated during 2005-2007 consecutively patients with AI with hormonal and CT examinations according a regional protocol. Two hundred and twenty-eight patients with AI with median size 2.0 cm were included. One mg overnight dexamethasone suppression test (DST) was performed in 223 patients and basal P-ACTH measured in 146 patients. SH was defined as cortisol ≥ 50 nmol/l at DST in combination with basal ACTH <2 pmol/l. In patients with unilateral AI 42% (76/180) had inadequate suppression at DST and 23% (27/115) had SH. The probability for SH and inadequate suppression at DST correlated positively to size and inversely to attenuation at CT. Bilateral AI were found in 43 patients and of these 70% (30/43) had inadequate suppression at DST and 42% (13/31) SH. The patients with SH or inadequate suppression at DST had increased frequency of hypertension which increased further in patients with post-DST cortisol ≥ 140 nmol/l. The applied criterion for SH is useful for initial evaluation of patients with AI. SH is common in patients with AI, particular in bilateral disease. In patients with unilateral AI the probability for SH correlated positively to size and inversely to attenuation at CT. Furthermore, SH and the post-DST cortisol concentration was associated with hypertension.

Clinical and biochemical impact of BCL1 polymorphic genotype of the glucocorticoid receptor gene in patients with adrenal incidentalomas

BACKGROUND

Adrenal incidentaloma (AI) is a common clinical problem. Subtle hormonal abnormalities are present in a substantial proportion of patients. BCL1 gene polymorphism of the glucocorticoid receptor (GR) is associated with increased sensitivity to glucocorticoid action. The genotype- phenotype associations of this polymomorphism in patients presenting with AI has not been extensively investigated.

AIM

A cross-sectional study in secondary/tertiary care centers.

SUBJECTS/METHODS

Ninety-five subjects with AI were genotyped for the BCL1 GR gene polymorphism. Patients underwent an oral glucose tolerance test and a dexamethasone suppression test (DST). The presence of subclinical hypercortisolism, features of metabolic syndrome, and osteoporosis/ osteopenia were also assessed.

RESULTS

No significant differences in markers of adrenal function between BCL1 carriers and non-carriers were revealed. Also, no difference was found in the features of metabolic syndrome, as well as in bone metabolism and density between these 2 groups. However, DST suppressor patients belonged more frequently to the BCL1 carriers group (41 out of 69 patients, 59.4% vs 9 out of 26 patients, 34.6%, p=0.0039), had smaller total adenoma size (2.4±0.2 cm vs 3.5±0.4 cm, p=0.04), and lower incidence of bilateral adrenal masses (18.8% vs 46.2%, p=0.01).

CONCLUSIONS

AI patients who also carry the polymorphic BCL1 variant exhibit smaller size adrenal nodules. Those AI patients with complete DST suppression had a higher incidence of the polymorphic BCL1 variant. However, this study failed to demonstrate any significant impact of BCL1 GR polymorphism on the frequency of cortisol-dependent co-morbidities in patients with AI.

High prevalence of autonomous aldosterone secretion among patients with essential hypertension

BACKGROUND

Previous studies based on standard endocrine testing have generally shown a low prevalence of primary aldosteronism, a form of autonomous aldosterone secretion (AAS), in hypertensive individuals. The purpose of this case-control study was to evaluate whether use of appropriately defined controls and combined testing reveal previously undetected AAS in hypertensives.

MATERIALS AND METHODS

We investigated aldosterone secretion in 180 hypertensives with (n = 44) and without (n = 136) adrenal adenomas on computerized tomography (CT) and 72 matched nonhypertensive individuals with normal adrenal CT. Serum aldosterone and active renin were measured, and the aldosterone/active renin ratio was calculated before and after a modified fludrocortisone-suppression test (FST). In the latter, to eliminate any stimulatory effect of endogenous stress-induced adrenocorticotrophin hormone on aldosterone secretion, we administered 1 mg of dexamethasone on the last day of the classical FST fludrocortisone/dexamethasone suppression test (FDST).

RESULTS

Using the 97·5 percentiles of serum aldosterone (74 pM L(-1)) and the aldosterone/renin ratio (32 pM L(-1) mU(-1) L(-1)) values obtained from the controls following the FDST, normal cut-off values indicative of adequate aldosterone suppression were established. Using the combination of these cut-offs, the estimated prevalence of AAS in patients with hypertension was 31%. Multiple linear regression analysis revealed a significant correlation between systolic and/or diastolic arterial blood pressure and the aldosterone value (P < 0·0001 and P < 0·01, respectively) and/or the aldosterone/renin ratio (P < 0·0001 and P < 0·01, respectively), which were obtained following the FDST.

CONCLUSIONS

By applying new cut-offs obtained following modification of standard testing, AAS is quite prevalent in hypertensive individuals and correlates highly with arterial blood pressure. This may have relevance for both the aetiology of the hypertension and its optimal therapy.

The functional status of incidentally discovered bilateral adrenal lesions

OBJECTIVE

To investigate autonomous cortisol and aldosterone secretion and insulin resistance (IR) indices, in patients with incidentally discovered bilateral adrenal lesions (BA).

PATIENTS

Thirty-six patients with BA, 113 patients with unilateral adrenal incidentalomas (UA) and 89 healthy subjects (C) with normal adrenal imaging.

MEASUREMENTS

All participants underwent adrenal imaging, baseline biochemical and hormonal measurements and the following investigations on consecutive days: (i) A 2-h oral glucose tolerance test (OGTT) (75 g) with glucose and insulin measurements every 30 min. (ii) An adrenocorticotrophin (ACTH) stimulation test with intravenous (i.v.) bolus administration of 250 μg of ACTH (1-24) and measurement of serum cortisol and aldosterone before and after 30 and 60 min. (iii) A low-dose dexamethasone suppression test (LDDST) (0·5 mg of dexamethasone every 6-h for 2 days) with cortisol measurement 6 h after the last dexamethasone dose and (iv) A NaCl (0·9%) postdexamethasone saline infusion test (PD-SIT) (2 l of NaCl 0·9% iv in 4 h) following the LDDST, with aldosterone measurement at the end of the test.

RESULTS

Cortisol and aldosterone cut-offs based on the mean + 2 SD values obtained from the C group following the LDDST and PD-SITs were calculated (34·11 nm and 74·83 pm, respectively). Based on the above cut-offs, autonomous cortisol and aldosterone secretion was found in 42·5 and 15·9% of patients with UA, and in 41·7 and 19·4% of patients with BA, respectively. In addition, 17·7% of patients with UA and 19·4% of patients with BA had concomitant autonomous cortisol and aldosterone secretion. Cortisol and aldosterone levels following the LDDST and PD-SIT were significantly higher in the BA compared to the UA group, respectively. Furthermore, patients with BA had more pronounced glucose levels and insulin resistance (IR) indices compared to patients with UA.

CONCLUSIONS

Patients with BA have more pronounced autonomous cortisol and aldosterone secretion and glucose metabolism alterations than patients with UA. Further studies are needed to evaluate the potential long-term consequences of these findings.

High prevalence of subclinical hypercortisolism in patients with bilateral adrenal incidentalomas: a challenge to management

OBJECTIVE

The prevalence of subclinical hypercortisolism (SH) in unilateral incidentalomas (UI) has been extensively studied; however, patients with bilateral incidentalomas (BI) have not been thoroughly investigated. We therefore aimed to describe the characteristics of patients with BI compared to their unilateral counterparts. The surgical outcome in a small number of patients is reported.

DESIGN

Observational retrospective study in a single secondary/tertiary centre.

PATIENTS

One hundred and seventy-two patients with adrenal incidentalomas (41 with BI).

MEASUREMENTS

Morning cortisol (F), ACTH, dehydroepiandrosterone sulphate (DHEA-S), midnight F, 24-h urine collection for cortisol (UFC), low-dose dexamethasone suppression test (LDDST), fasting glucose, insulin, and oral glucose tolerance test (OGTT). Primarily, SH was defined as F-post-LDDST>70 nmol/l and one more abnormality; several diverse cut-offs were also examined.

RESULTS

No difference was noted in age, body mass index, or prevalence of diabetes and impaired glucose tolerance between patients with UI and those with BI. Patients with BI had higher F-post-LDDST (119·3 ± 112·8 vs 54·3 ± 71·5 nmol/l, P<0·001) and lower DHEA-S (1·6 ± 1·5 vs 2·5 ± 2·3 μmol/l, P=0·003) but similar UFC, ACTH and midnight F levels, compared to UI. SH was significantly more prevalent in BI (41·5%vs 12·2%, P<0·001). Fourteen patients were operated on; four underwent bilateral interventions. In 10 patients, unilateral adrenalectomy on the side of the largest lesion resulted in significant improvement in F-post-LDDST (P=0·008) and a decrease in midnight F (P=0·015) levels.

CONCLUSIONS

Subclinical hypercortisolism is significantly more prevalent in bilateral incidentaloma patients, posing great dilemmas for its optimum management.

High prevalence of autonomous cortisol and aldosterone secretion from adrenal adenomas

OBJECTIVES

Previous studies based on standard endocrine testing have shown a variable incidence of autonomous cortisol secretion (ACS) or autonomous aldosterone secretion (AAS) in patients with single adrenal adenomas (SAA). We tested whether the use of appropriate controls and modification of standard testing, aiming at eliminating interference from endogenous ACTH, reveals previously undetected subtle ACS and AAS by SAA.

DESIGN

Case control study. Patients We investigated 151 patients with SAA and 72 matched controls with normal adrenal computerized tomography.

MEASUREMENTS

All participants had arterial blood pressure recorded, and serum cortisol and aldosterone measured before and after intravenous administration of 250 mug of ACTH, and following dexamethasone administration. Eighty-three patients and all the controls had serum aldosterone and renin measured before and after saline infusion, and after a second saline infusion following dexamethasone administration.

RESULTS

Using the mean + 2 SD values obtained from controls after dexamethasone administration and saline infusion following dexamethasone administration, normal cut-off values for cortisol (30.11 nM), aldosterone (67.59 pM), and aldosterone/renin ratio (9.74 pM/mU/l) were developed. Using these cut-off values, the estimated incidence of ACS and AAS in patients with SAA was 56.63% and 24.10%, respectively, whereas 12.05% had autonomous secretion of both cortisol and aldosterone. Systolic and diastolic arterial blood pressure correlated significantly with the aldosterone/renin ratio following AlphaCTH stimulation (P < 0.0002 and P < 0.001, respectively), and after saline infusion following dexamethasone administration (P < 0.003 and P < 0.002, respectively).

CONCLUSIONS

By applying new cut-offs, ACS and AAS in patients with a SAA is very common, and aldosterone secretion correlates with arterial blood pressure.

Hormonal activity of adrenal incidentalomas: results from a long-term follow-up study

OBJECTIVE

To investigate the natural course of apparently benign adrenal incidentalomas with no overt hyperfunction at diagnosis, as their clinical significance and appropriate management are still controversial.

DESIGN

Prospective long-term follow-up study of patients with adrenal incidentalomas with periodic hormonal and morphological evaluation.

PATIENTS AND METHODS

A total of 77 patients with incidental adrenal masses, diameter 1.0-6.0 cm (median 2.5 cm), were submitted to a hormonal assessment of adrenal function at diagnosis. This was repeated, together with an adrenal CT scan, 12 months later and then every 12-24 months, for a period of 12-154 months (mean 62.7 +/- 31.9, median 60.0).

RESULTS

At diagnosis, 57 patients had normal adrenal function and 20 had subclinical Cushing's syndrome. During follow-up, adrenal function remained normal in 49 patients, subclinical Cushing's syndrome was confirmed in 12, whilst intermittent subclinical autonomous cortisol hypersecretion was found in 12 patients. Overt endocrine disease was diagnosed in 4 patients (Cushing's syndrome in 2 and phaeochromocytoma in 2). A change in mass size (> or = 0.5 cm) was observed in 26 patients (enlargement in 20--including patients who developed overt hyperfunction--with no signs of malignancy and reduction in size in 6).

CONCLUSIONS

Subclinical autonomous cortisol hypersecretion is the most frequent hormonal abnormality in patients with adrenal incidentalomas, and may be intermittent in a significant percentage of cases. Few patients develop overt endocrine disease. A growth tendency is observed in some adrenal incidentalomas without evidence of malignant transformation and occasionally can be related to development of overt hyperfunction. These findings indicate the need for periodic hormonal and morphological evaluation for several years.

Atherosclerotic risk factors and complications in patients with non-functioning adrenal adenomas treated with or without adrenalectomy: a long-term follow-up study

OBJECTIVE

Despite the increased prevalences of hypertension, type 2 diabetes mellitus (T2DM), hyperlipidemy, and obesity in patients with non-functioning adrenal adenomas (NFAAs), there is a paucity of data on long-term atherosclerotic morbidity as well as the long-term cardiovascular effects of adrenalectomy in these patients.

DESIGN, PATIENTS, AND METHODS

This retrospective study includes the results of baseline and follow-up investigations of 125 patients (29 males and 96 females; mean age 60.1 years) with NFAAs referred for endocrine evaluation between 1990 and 2001. Of the 125 patients, 47 underwent unilateral adrenalectomy, while 78 patients were followed conservatively. These patients were reinvestigated after a mean follow-up time of 9.1 (5-16) years in 2006, with special emphasis on laboratory and other atherosclerotic risk factors (ARF), vascular events, and interventions.

RESULTS

The prevalences of hypertension, impaired glucose tolerance or T2DM, hyperlipidemy, and obesity were 82, 43, 58, and 50%, and 89, 58, 82, and 50% at baseline and follow-up, respectively. None of the investigated ARF prevalences were different between patients treated and not treated with adrenalectomy, and between patients with and without subclinical Cushing's syndrome. The prevalences of angina pectoris, acute myocardial infarction, coronary, and peripheral arterial interventions or cerebrovascular stroke did not differ significantly between patients treated and not treated with adrenalectomy.

CONCLUSION

Our study confirms previous investigations reporting markedly increased prevalences of various ARF in patients with NFAAs. Adrenalectomy performed in these patients failed to decrease the prevalence of ARF and atherosclerotic morbidity.

Endogenous subclinical hypercortisolism: Diagnostic uncertainties and clinical implications

Subclinical hypercortisolism (SH) is a newly characterized hormonal disorder that is almost exclusively detected in the context of incidentally discovered adrenal masses. The diagnostic criteria used for the definition of this condition are at present controversial. Amongst the various tests used for the detection of this abnormality (dexamethasone suppression, urinary free cortisol, ACTH levels, midnight serum or salivary cortisol concentrations, ACTH responses to CRH stimulation), the dexamethasone suppression tests (DST) seem to better accomplish the task of unmasking subtle abnormalities of cortisol secretion. Several versions of DST have been used: the 1-mg overnight, the 3-mg overnight and the classical 2-day low-dose DST. This latter test has the theoretical advantage that, by more efficiently suppressing pituitary ACTH secretion, it may provide a measure of the residual (ie non- ACTH-dependent) cortisol secretion from the adrenal mass. In this way, post-dexamethasone cortisol concentrations may quantify the degree of autonomous cortisol hypersecretion. In fact, post-dexamethasone cortisol concentrations have a negative correlation with basal ACTH levels and a positive correlation with midnight cortisol concentrations as well as the size of the incidentally discovered adrenal mass. Most of the existing data indicate that SH detected in the context of adrenal incidentalomas may have some clinically significant implications. In fact, patients with higher post-dexamethasone cortisol concentrations demonstrate higher lipid levels and lower bone mass densities. It has also been suggested that SH may be responsible for biochemical and phenotypic changes reminiscent of the metabolic syndrome. In summary, SH does exist and is associated with a negative impact in patients' health; however, hormonal cut-off criteria for decision-making remain to be defined.

Evaluation of GH reserve in patients with adrenal incidentalomas and biochemical evidence of subclinical autonomous glucocorticoid hypersecretion

OBJECTIVE

Although it is well established that overt hypercortisolism in patients with active Cushing's syndrome leads to a profound suppression of stimulated GH secretion, the role of subclinical autonomous glucocorticoid hypersecretion (SAGH), currently detected with increasing frequency in patients with adrenal incidentalomas, on GH secretory reserve has received little attention. The aim of the present study was to evaluate whether SAGH in patients presented with adrenal incidentalomas has a negative effect on GH secretory reserve.

DESIGN AND PATIENTS

Sixteen patients with overt Cushing's syndrome (CS) and 36 patients with adrenal incidentalomas were investigated. The latter group was further divided in 23 patients who demonstrated an adequate suppression of cortisol levels (of < 70 nmol/l) following the low-dose dexamethasone suppression test (LDDST) and in 13 patients, who failed to suppress (cortisol levels post-LDDST > 70 nmol/l). The former group was defined as normocortisolaemic (NC) and the latter group as representing patients with SAGH. The combined pyridostigmine + GHRH test (PD + GHRH) was used to assess the GH secretory reserve of these patients.

RESULTS

Peak GH levels following PD + GHRH administration were significantly lower in CS patients compared to both the NC and SAGH group of patients with adrenal incidentalomas (2.2 +/- 0.7 vs. 18.9 +/- 2.6 and 21.5 +/- 3.6 microg/l, respectively, P < 0.05); no difference was observed in peak GH responses between the NC and SAGH group of patients. A subnormal GH response (defined as GH(max) < 12.8 microg/l) was observed in all 16 patients with CS. However, only seven NC and three SAGH patients failed to respond adequately. Correlation analysis revealed a negative correlation between peak GH response to PD + GHRH and plasma cortisol concentrations in CS patients (R =-0.6, P = 0.012), while in patients with adrenal incidentalomas such a correlation was absent. Contrary to patients with CS in whom body mass index (BMI) was not correlated to peak GH, a significant negative correlation between peak GH response to PD + GHRH and BMI was disclosed in patients with adrenal incidentalomas (R =-0.49, P = 0.003). In these patients, again contrary to CS patients, a significant negative correlation was also found between peak GH post PD + GHRH and age (R = -0.46, P = 0.002).

CONCLUSIONS

In conclusion, our results provide evidence that, contrary to patients with overt CS, SAGH does not affect the GH secretory response to provocative stimulation.

The clinically inapparent adrenal mass: update in diagnosis and management

Clinically inapparent adrenal masses are incidentally detected after imaging studies conducted for reasons other than the evaluation of the adrenal glands. They have frequently been referred to as adrenal incidentalomas. In preparation for a National Institutes of Health State-of-the-Science Conference on this topic, extensive literature research, including Medline, BIOSIS, and Embase between 1966 and July 2002, as well as references of published metaanalyses and selected review articles identified more than 5400 citations. Based on 699 articles that were retrieved for further examination, we provide a comprehensive update of the diagnostic and therapeutic approaches focusing on endocrine and radiological features as well as surgical options. In addition, we present recent developments in the discovery of tumor markers, endocrine testing for subclinical disease including autonomous glucocorticoid hypersecretion and silent pheochromocytoma, novel imaging techniques, and minimally invasive surgery. Based on the statements of the conference, the available literature, and ongoing studies, our aim is to provide practical recommendations for the management of this common entity and to highlight areas for future studies and research.

Obesity and endocrine disease

Several endocrine abnormalities are reported in obesity. Some of these abnormalities are considered as causative factors for the development of obesity, whereas others are considered to be secondary effects of obesity and usually are restored after weight loss. Thyroid hormones usually are normal in obesity, with the exception of T3 which is elevated. Prolactin is normal but prolactin response to different stimuli is blunted. GH is low and GH response to stimuli is blunted. IGF-I levels are normal or elevated. Cortisol, ACTH, and urine free cortisol levels are usually normal; however, a hyperresponsiveness of the HPA axis with increased cortisol and ACTH response to stimulatory tests is observed in centrally obese individuals. Total testosterone and SHBG levels are low, but free testosterone levels are usually normal in obese men. LH and FSH levels usually are normal and estrogens are elevated. Norepinephrine levels are elevated, whereas epinephrine levels are low or normal. Aldosterone levels are elevated but renin activity is usually normal. Parathyroid hormone levels are elevated with normal serum calcium levels and increased urine calcium levels. Monogenic mutations that result in severe obesity have been described in several individuals. Also, several endocrine diseases have obesity as one their clinical manifestations. Hypothyroidism, Cushing's syndrome, GH and testosterone deficiency, polycystic ovarian syndrome, insulinoma, hypothalamic lesions, and genetic syndromes often present with obesity. In most of these conditions, appropriate treatment of the primary disease results in weight loss. In addition, the fat cell has been found to be an endocrine organ that produces several peptides that are bioactive and participate in the regulation of adipocyte function.

Occult Cushing's syndrome in type-2 diabetes

Subclinical Cushing's syndrome (SCS) caused by adrenal incidentalomas is frequently associated with overweight and insulin resistance. Metabolic syndrome X may therefore be a clue to the presence of CS. However, the incidence of CS in this situation remains unknown. We have conducted a prospective study to evaluate the prevalence of occult CS in overweight, type-2 diabetic patients devoided of specific clinical symptoms of CS. Two hundred overweight, type-2 diabetic patients, consecutively referred for poor metabolic control (HbA(1C) > 8%), were studied as inpatients. A first screening step was performed with the 1-mg overnight dexamethasone suppression test (DST) using a revised criterion for cortisol suppression (60 nmol/liter) to maximize the sensitivity of the procedure. A second confirmatory step of biochemical investigations (midnight plasma cortisol concentration, plasma cortisol circadian rhythm, morning plasma ACTH concentration, 24-h urinary free cortisol, and 4-mg i.v. DST) was performed in patients with impaired 1-mg DST. A third step of imaging studies was performed according to the results of second-step investigations. Fifty-two patients had impaired 1-mg DST. Among these, 47 were further evaluated. Thirty were considered as false positives of the 1-mg DST, whereas 17 displayed at least one additional biological abnormality of the hypothalamic-pituitary-adrenal axis. Definitive occult CS was identified in four patients (2% of the whole series) with Cushing's disease (n = 3) and surgically proven adrenal adenoma (n = 1). Definitive diagnosis remains to be established in seven additional patients (3.5%) with mild occult CS associated with unsuppressed plasma ACTH concentrations and a unilateral adrenal tumor of 10-29 mm in size showing prevalent uptake at radiocholesterol scintigraphy. In conclusion, a relatively high prevalence of occult CS was found in our study. Further studies are needed to evaluate the impact of the cure of occult CS on obesity and diabetes mellitus in these patients. Such studies might provide a rationale for systematic screening of occult CS in this population.

Does subclinical hypercortisolism adversely affect the bone mineral density of patients with adrenal incidentalomas?

OBJECTIVE

Subclinical hypercortisolism (SH) is detected increasingly in a substantial proportion of patients with incidentally discovered adrenal adenomas. The clinical implications of SH are currently unclear. Osteoporosis is a well-known complication of glucocorticoid excess. So far, the impact of SH on bone mineral density (BMD) has been studied in a limited number of reports with discordant results. In the present study we evaluated the BMD in a large cohort of post-menopausal women with adrenal incidentalomas. : patients and measurements Forty-two post-menopausal women with incidentally discovered adrenal masses and radiological features highly suggestive of benign adrenal adenomas were investigated. All patients underwent a standard low-dose dexamethasone suppression test (LDDST; 0.5 mg 6-hourly for 2 days). The diagnosis of subclinical hypercortisolism (SH) was based on post-LDDST cortisol concentrations of > 70 nmol/l. According to this criterion patients were subdivided into two groups: with (n = 18; group A) or without (n = 24; group B) SH. There was no significant difference in age, years since menopause and body mass index between these groups. BMD was measured at L2-L4 vertebrae and three sites of the proximal femur by the dual energy X-ray absorptiometry (DEXA) method.

RESULTS

Post-menopausal women with SH (group A) exhibited slightly but significantly lower absolute and age-adjusted BMD values compared to group B patients in the femoral neck (BMD g/cm2: 0.72 +/- 0.08 vs. 0.79 +/- 0.09; Z-score: -0.20 +/- 0.82 vs. +0.43 +/- 0.94, P < 0.05) and trochanter (BMD g/cm2: 0.60 +/- 0.09 vs. 0.69 +/- 0.10; Z-score: -0.32 +/- 1.0 vs. +0.30 +/- 1.05, P < 0.01). BMD measurements of the Ward's triangle were also lower in group A patients but the difference did not reach statistical significance (BMD g/cm2: 0.60 +/- 0.10 vs. 0.68 +/- 0.13, P = 0.06). There was no difference in the lumbar vertebrae between the two groups (BMD g/cm2: 0.888 +/- 0.13 vs. 0.90 +/- 0.16, P = 0.78; z-score: +0.50 +/- 1.16 vs. +0.11 +/- 1.5, P = 0.36). The number of patients in the osteoporotic range was minimal with no significant difference between the two groups. However, the frequency of osteopenia in group A was significantly greater than in group B patients in the trochanter and Ward's triangle areas. Serum osteocalcin (BGP) levels were significantly lower in group A compared to group B patients (18.6 +/- 8.6 vs. 26.2 +/- 8.1 ng/ml, P < 0.01); no difference existed regarding parathyroid hormone (PTH) concentrations (43 +/- 15.6 vs. 41.2 +/- 14.8 pg/ml, P = 0.72).

CONCLUSIONS

In this series, post-menopausal women with subclinical hypercortisolism had lower absolute and age-adjusted BMD values and a higher rate of osteopaenia in the trabecular loaded and mixed cortical-trabecular bone of proximal femur. These data demonstrate that the subtle hypercortisolism of patients with adrenal incidentalomas may have an adverse effect on the bone mass of these patients.

[Bone mineral density and biological markers of bone repair in patients with adrenal incidentaloma: effect of subclinical hypercortisolism]

PURPOSE

Some adrenal incidentalomas produce cortisol in mild excess ('subclinical' Cushing's adenomas) and can potentially induce osteopenia. Their diagnosis is usually based on exclusive tumour uptake on adrenal scintigraphy using 131I-6 beta-methyl-iodo-19-norcholesterol and on inadequate cortisol response to dexamethasone (DXM) suppression tests. The aims of the present study were to evaluate bone mineral density (BMD) and metabolic markers of bone turnover in patients with incidentalomas and to test the effect of mild hypercortisolism on bone parameters.

METHODS

Thirty-five patients (13 men, 22 postmenopausal women, 49-76 years) with unilateral incidentaloma were studied. BMD was measured by dual X-ray absorptiometry. Two biochemical markers of bone formation, serum osteocalcin (BGP) and bone alkaline phosphatase (bALP), and two markers of bone resorption, urinary free deoxypyridinoline (D-Pyr) and urinary carboxy-telopeptide of bone type 1 collagen (CTX), were measured by radioimmunoassay. D-Pyr and CTX were corrected for creatinine excretion.

RESULTS

Median values of lumbar and femoral T-score were -1.125 and -0.920, respectively, whereas corresponding Z-score values where normal (0.105 and 0.120, respectively). Thirty-nine percent of patients had low serum BGP values and 3% had low bALP values; 16% showed elevated D-Pyr/creatinine values and 23% increased CTX/creatinine values. Patients both with suppression of the contralateral adrenal on scintigraphy and with an inadequate cortisol response to 1 mg DXM (> 50 nmol/L) (n = 14) presented a lower femoral T-score (P < 0.02) and, to a lesser extent, a lower femoral Z-score (P = 0.11) than other patients (n = 21). The proportion of increased values of CTX/creatinine (42% versus 11%, P = 0.08) also tended to be higher in the first than in the second group of patients. These two groups of patients were similar in terms of age, but tumour size was larger (P < 0.04) and plasma ACTH value was lower (P < 0.02) in patients with scintigraphic and endocrine abnormalities.

CONCLUSION

Subclinical hypercortisolism defined on the basis of scintigraphic and hormonal criteria seems to contribute to bone loss in patients with adrenal incidentaloma. As other possible side effects of mild hypercortisolism, these findings have to be taken into account in the therapeutic management of these patients.

Diurnal changes in glucocorticoid sensitivity in human peripheral blood samples

The secretion of cortisol, a principle homeostatic regulator in humans, shows a circadian rhythm, with high concentrations in the morning and low levels in the evening and at night. Tissue response to hormones is dependent on hormone concentrations but also on a variety of cellular factors, such as hormone receptors, transcription factors, and activators. In this report, we evaluated whether cell sensitivity to glucocorticoids (GCs) is also subject to diurnal variation using a whole cell system (whole blood samples) stimulated by lipopolysacharide to induce the production of tumor necrosis factor (TNF-alpha); the induction of TNF-alpha is inhibited by dexamethasone. Blood samples obtained in the morning (08.30-09.00 h) and in the evening (22.30-23.00 h) from 37 healthy individuals (18 males, 19 females) aged 29+/-3 years were treated with lipopolysacharide in the presence or absence of 10(-6) M dexamethasone, and the percentage of inhibition of TNF-alpha production was used as an index of sensitivity to GCs. The mean +/- SD in morning samples was 43.5+/-13.8% for the general population, 42.3+/-14.0% for males and 44.6+/-13.8% for females, whereas that in the evening samples was 36.5+/-15.7%, 35.6+/-13.8% and 37.4+/-17.7%, respectively. The results support a significantly increased sensitivity to GCs in the morning hours compared with that in the evening in the general population (P<0.001) as well as in males (P<0.001) and in females (P<0.001). No sex related differences in sensitivity to GCs were observed in the morning or in the evening hours. The sensitive and reproducible assay utilized in this study could also be used to investigate the sensitivity to GCs in various diseases characterized by resistance to GCs and/or alterations in glucocorticoid receptor function.

Adrenal incidentalomas showing unilateral concordant visualization by adrenocortical scintigraphy: comparison with adenomas in Cushing's syndrome

An adrenocortical adenoma causing Cushing's syndrome (Cushing's adenoma) produces a unilateral concordant visualization (UCV) imaging pattern in which the adenoma is only visualized on radioiodocholesterol adrenocortical scintigraphy. But because this imaging pattern is also noted in some patients with adrenal incidentalomas, we examined whether the UCV-incidentaloma was essentially identical with Cushing's adenoma and would develop Cushing's syndrome. The subjects were 9 patients with UCV-incidentalomas (mean size, 30 mm; range, 20-45 mm) and 6 patients with Cushing's adenomas (mean size, 28 mm; range, 25-35 mm). Endocrinological evaluations showed several abnormalities including blunted diurnal rhythm of plasma cortisol within the normal range, low plasma ACTH and/or high 24-hr urinary 17-OHCS levels in 8 of 9 patients with UCV-incidentalomas, but these abnormalities did not meet the diagnostic criteria of Cushing's syndrome. Adrenal uptake of the tracer in the patients with UCV-incidentalomas was not statistically different from that in the patients with Cushing's adenomas and had no relationship with hormonal values in either patient group. Tumor size on CT correlated with the levels of 24-hr urinary 17-OHCS (r = 0.75, p = 0.02) and plasma cortisol at 7:00 (r = 0.82, p = 0.007) in the patients with UCV-incidentalomas, but not in the patients with Cushing's adenomas. Although 3 UCV-incidentalomas increased slightly in size, none of 9 patients with UCV-incidentalomas has developed Cushing's syndrome for 4 to 52 months. These results suggest that the UCV-incidentaloma may be essentially different from the Cushing's adenoma and unlikely to develop Cushing's syndrome.

Management approaches to adrenal incidentalomas. A view from Rochester, Minnesota

Two biproducts of the revolution in diagnostic imaging techniques are unintended discoveries, and uncertainty for the patient and the clinician. To address the uncertainty associated with adrenal incidentalomas, clinicians need to understand the definition, differential diagnosis, and options for assessment with respect to functional status and malignancy potential. This article presents an algorithmic approach that addresses these issues.

Management approaches to adrenal incidentalomas. A view from Ancona, Italy

The definition of adrenal incidentaloma encompasses a heterogeneous spectrum of pathologic entities, including primary adrenocortical and medullary tumors, benign or malignant lesions, hormonally active or inactive lesions, metastases, and infections. This article provides an overview of the diagnostic clinical approach and management of the incidentally discovered adrenal masses. Approaches are based on data collected in more than 1000 cases of the Collaborative Study Group on Adrenal Incidentaloma of the Italian Society of Endocrinology and the authors' experience.

Assessment of cortisol and ACTH responses to the desmopressin test in patients with Cushing's syndrome and simple obesity

OBJECTIVE

The desmopressin test has recently been introduced in clinical practice as an adjunctive tool in the differential diagnosis of ACTH-dependent Cushing's syndrome (CS). It has been reported that the majority of patients with pituitary-dependent CS (Cushing's disease, CD) respond to desmopressin, while no such response is usually observed in other forms of this syndrome. In the present study, the responsiveness of the HPA axis to desmopressin was studied in a group of obese subjects. In addition, the ability of desmopressin administration to differentiate between patients with obesity and the various forms of Cushing's syndrome was investigated.

DESIGN AND SUBJECTS

Cortisol and ACTH responses to the administration of desmopressin (10 microg bolus i.v.) were examined in 20 consecutive patients with obesity (14 women and six men; BMI range: 34.5-66.7 kg/m2). Obese subjects had no clinical stigmata of CS. In all obese patients, either an overnight (dex 1 mg at 2300 h) (n = 8) or a formal low-dose (dex 0.5 mg 6-hourly for 2 days) (n = 12) dexamethasone suppression test was performed for the exclusion of Cushing's syndrome. Three of eight subjects showed failure of cortisol suppression (i.e. F > 28 nmol/l) to the overnight dexamethasone suppression test, but they had undetectable cortisol levels (< 28 nmol/l) on further testing with the formal 2-day test. All but two of the remaining subjects had undetectable cortisol levels (< 28 nmol/l) following the formal 2-day, low-dose, dexamethasone suppression test. For comparison, desmopressin responses were also tested in 33 patients with CS of varied aetiologies (25 patients with pituitary-dependent CS, three patients with occult ectopic ACTH secretion and five patients with primary adrenal CS). A positive response was considered to be an increment greater than 20% and 50% from baseline levels of cortisol and ACTH, respectively.

RESULTS

Mean cortisol (F) and ACTH levels did not differ from the baseline at any time point following desmopressin administration in the obese group (basal F: 417 +/- 41, peak F: 389 +/- 32 nmol/l, P > 0.05; basal ACTH: 33.5 +/- 4.3, peak ACTH: 50.6 +/- 16.6 ng/l, P > 0.05), or in patients with occult ectopic or primary adrenal CS. In contrast, in the group of patients with CD, there was a significant rise in the mean ACTH and F levels from baseline (basal F: 725 +/- 50, peak F: 1010 +/- 64 nmol/l, P < 0.01; basal ACTH: 88.6 +/- 11.8, peak ACTH: 351 +/- 64 ng/l, P < 0.01). Cortisol responses greater than 20% from baseline were observed in 21/25 (84%) patients with CD, but in only 3/20 (15%) of the obese patients. With regard to ACTH, increments greater than 50% over baseline were observed in 23/25 (92%) of patients with CD, and in only 3/20 (15%) of the obese patients. As previously reported, none of the patients with occult ectopic ACTH secretion or primary adrenal CS had a positive response.

CONCLUSIONS

The prevalence of subjects who met the criteria adopted to define positive cortisol and ACTH responses to the desmopressin test was significantly higher in the group of patients with Cushing's disease than in the group of patients with obesity. It is therefore suggested that this test may be occasionally useful in the differentiation between simple obesity and the pituitary-dependent form (but not other forms) of Cushing's syndrome.

Elevated post-dexamethasone suppression cortisol concentrations correlate with hormonal alterations of the hypothalamo-pituitary adrenal axis in patients with adrenal incidentalomas

OBJECTIVE

It has recently been suggested that autonomous cortisol production may lead to subclinical glucocorticoid excess in a substantial number of patients with incidentally discovered adrenocortical adenomas. Following a standard low-dose dexamethasone suppression test (LDDST) cortisol concentrations are frequently incompletely suppressed in patients with adrenal incidentalomas, due to an ACTH-independent secretion of cortisol by the adrenal mass. Thus, post LDDST cortisol concentrations may provide a measure of the degree of autonomous glucocorticoid secretion, but hormonal alterations in relation to post-LDDST cortisol concentrations have not been thoroughly investigated.

PATIENTS AND MEASUREMENTS

61 patients with radiological features highly suggestive of adrenal adenomas were studied. These included 43 women, 18 men; mean age 59 +/- 1.4, range: 25-76 years; BMI 30.9 +/- 0.8 kg/m2 and waist:hip ratio 0.90 +/- 0.016. All subjects underwent a standard LDDST, as follows: after a 48-hr stabilisation period, 24-hr urine collections for basal urinary free cortisol (UFC) were performed. Basal serum cortisol and plasma ACTH were measured at 8 AM and at midnight the following day, and subjects started dexamethasone 0.5 mg 6 hourly for 2 days. Post-dexamethasone cortisol and ACTH levels were measured at 8 AM, 6-hrs after the last dose of dexamethasone. Blood samples for dehydroepiandrosterone sulphate (DHEAS) and serum lipids were obtained on the morning preceding dexamethasone administration.

RESULTS

Post-LDDST cortisol concentrations correlated positively with the size of the adenoma (r = +0.527, P < 0.001). There was a negative rank correlation of post-LDDST cortisol concentrations and basal ACTH levels at 0900 h (rs = -0.426, P < 0.001) and DHEAS (rs = -0.380, P = 0.006). Moreover, there was a good rank correlation between DHEAS and basal ACTH levels (rs = +0.456, P < 0.001). A positive rank correlation was observed between post-LDDST cortisol concentrations and midnight cortisol concentrations (rs = +0.317, P = 0.020). As recent studies have suggested that post-LDDST cortisol levels higher than 70 nmol/l may indicate significant hypercortisolism comparisons were also performed between patients divided according to post-LDDST cortisol values into 3 groups: Group A, > 70 nmol/l (19 pts); Group B, 30-70 nmol/l (27 pts); Group C, < 30 nmol/l (15 pts). Although there was no difference in basal cortisol and UFC values between these groups, ACTH and DHEAS levels were significantly lower, and midnight cortisol significantly higher in group A compared to group C patients (P = 0.030, P = 0.017 and P = 0.001 respectively). Cholesterol and triglyceride levels were slightly albeit significantly higher in group A compared to group C patients (P < 0.05).

CONCLUSIONS

It is concluded that higher post-low dose dexamethasone cortisol concentrations are associated with lower ACTH and dehydroepiandrosterone sulphate, higher midnight cortisol concentrations and larger adenomas. These findings are consistent with the hypothesis that post-low dose dexamethasone cortisol concentrations represent a useful index in assessing subtle glucocorticoid autonomy in patients with adrenal adenomas.