Diagnostic performance of late-night salivary cortisol measured by automated electrochemiluminescence immunoassay in obese and overweight patients referred to exclude Cushing's syndrome

This study estimates diagnostic performance of late-night salivary cortisol (LNSC) as measured by automated electrochemiluminescence immunoassay (ECLIA), evaluates the clinical implication of two consecutive LNSC measurements, and compares its accuracy with enzyme-linked immunosorbent assay (ELISA) and serum cortisol after low-dose dexamethasone suppression test (DST) in obese and overweight patients referred for suspected Cushing's syndrome (CS). One hundred twenty three consecutive obese and overweight referred patients and 98 healthy volunteers provided two saliva samples collected at 23:00 using a Salivette (Sarstedt, Germany), assayed by ECLIA (Cobas e601) and ELISA. The patients underwent DST and were further evaluated until CS was pathologically confirmed (n?=?45) or excluded. Diagnostic performance of LNSC was evaluated by receiver operating characteristic (ROC) analysis. The total areas under the curve (AUC) were calculated to compare the different tests. We found that a cut-off value of 9.4?nmol/l can differentiate CS among obese and overweight patients with sensitivity of 84.4?% (95% CI 71.2-92.2), specificity of 92.3?% (95% CI 84.2-96.4), and diagnostic odds ratio of 65.1 (95% CI 20.4-207.6). No difference was found between AUCs from the first, second, and the mean from the two LNSC measurements (ECLIA), LNSC (ELISA), or DST. The single LNSC (ECLIA) and DST improved the sensitivity and specificity for concordant results up to 100 and 97.4?%, respectively. In conclusion, due to its automation and its comparable diagnostic performance, ECLIA is preferable as a first-line LNSC screening test for CS. The initial use of single LNSC followed by DST provides better diagnostic performance for concordant results.     

Diagnostic value of salivary cortisol in Cushing's syndrome (CS)

Objective The diagnosis of Cushing's syndrome (CS) remains a challenge in clinical endocrinology. The aim of this study was to determine the reproducibility and diagnostic value of late‐night salivary cortisol (SAF₂₃) for CS and its utility along the follow‐up of treated patients. In addition, using the same radioimmunoassay reactives, the cut‐off values for saliva and serum cortisol, assessed synchronically after the overnight 1 mg dexamethasone suppression test (DST), were defined. Design Twenty‐one patients with confirmed CS and 121 volunteers were studied. All the subjects collected 24‐h urine for cortisol (UFC). On the same day whole saliva was obtained from the subjects at 23 h for SAF₂₃. The intraclass coefficient of correlation (ICC) of SAF₂₃ was estimated in 47 subjects (21 CS and 26 C). At 8 h, after DST, simultaneous saliva and serum samples for cortisol (SAF_dex and F_dex, respectively) were obtained in 51 subjects (17 CS and 34 C). After specific therapy, 18 patients with CS were followed with SAF₂₃ measurements. SAF and F were expressed as nm . Results The intraclass coefficient of correlation of SAF₂₃ was 0·89 in CS and 0·83 in C. SAF₂₃ > 3·8 nm showed a sensitivity and specificity of 100% and 97·5%, respectively, for diagnosing CS. SAF₂₃ correlated positively with UFC (r = 0·685; P = 0·0001). After DST, SAF_dex significantly correlated with F_dex (r = 0·61, P < 0·0001). A cut‐off value of SAF_dex > 2·0 nm and F_dex > 50·0 nm detected CS with 100% sensitivity and specificity. After successful surgical therapy, 13 patients with CS had SAF₂₃ levels < 3·8 nm (1·4 ± 0·8 nm ). Conclusions SAF₂₃ and SAF_dex seem to be good screening tools based on their noninvasive nature, remarkable reproducibility and diagnostic performances.     

Reproducibility and performance of one or two samples of salivary cortisol in the diagnosis of Cushing's syndrome using an automated immunoassay system

The purpose of this article is to evaluate the variability and reproducibility of late night salivary cortisol (LNSC) using electrochemiluminescence immunoassay (ECLIA) and compare the accuracy of one or two samples in diagnosis of Cushing's syndrome (CS). We prospectively included 64 healthy volunteers (HV), 35 patients with clinically suspected CS (S), and 26 patients with confirmed CS. Nine patients in the CS group had 24-h urinary free cortisol (UFC) less than two times the upper limit of normal (mild CS). UFC and two consecutive LNSC (LNSC1, LNSC2) were collected at home. All patients in the S group had normal UFC and low-dose dexamethasone suppression test. No differences were found between the HV and S groups in UFC, LNSC1, and LNSC2. Intra-individual variability between the two samples of LNSC was 22% in HV (1.6-91%), 32% in the S group (1.6-144%), and 51% (1.6-156%) in the CS group. Variability was higher in CS patients than those in the HV (P?相似文献   

Midnight salivary cortisol versus urinary free and midnight serum cortisol as screening tests for Cushing's syndrome

The diagnosis of Cushing's syndrome (CS) is often a challenge. Recently, the determination of late night salivary cortisol levels has been reported to be a sensitive and convenient screening test for CS. However, no studies have included a comparison with other screening tests in a setting more closely resembling clinical practice, i.e. few patients with CS to be distinguished from patients with pseudo-Cushing states (PC), including the large population of obese patients. The aim of this study was to compare the diagnostic performance of midnight salivary cortisol (MSC) measurement with that of midnight serum cortisol (MNC) and urinary free cortisol (UFC) in differentiating 41 patients with CS from 33 with PC, 199 with simple obesity, and 27 healthy normal weight volunteers. Three patients with CS had MSC levels lower than the cut-off point derived from receiver operator characteristic analysis (9.7 nmol/liter), yielding a sensitivity for this parameter of 92.7%. In the whole study population, no statistically significant differences in terms of sensitivity, specificity, diagnostic accuracy, and predictive values were observed among tests. In particular, the overall diagnostic accuracy for MSC (93%; 95% confidence interval, 90.1-95.9%) was similar to those of UFC (95.3%; 94.1-96.5%) and MNC (95.7%; 93.4-98%; both P = NS). The diagnostic performance of MSC was superimposable to that of MNC also within the area of overlap in UFC values (< or =569 nmol/24 h) between CS and PC. In conclusion, MSC measurement can be recommended as a first-line test for CS in both low risk (simple obesity) and high-risk (i.e. PC) patients. Given its convenience, this procedure can be added to tests traditionally used for this purpose, such as UFC and MNC.     

Reproducibility of nighttime salivary cortisol and its use in the diagnosis of hypercortisolism compared with urinary free cortisol and overnight dexamethasone suppression test

BACKGROUND/METHODS: Nighttime salivary cortisol (NSC) has been suggested to be a useful diagnostic test for Cushing's syndrome (CS). In the absence of published data on its day-to-day variability, we assessed the reproducibility of NSC by repeated measurements in healthy volunteers. Its diagnostic performance was compared with 24-h urinary free cortisol (UFC) and 1 mg overnight dexamethasone suppression test in 12 patients with CS, 20 healthy volunteers, 14 referred patients in which CS was excluded or not firmly established, 16 obese patients, and 20 women in late pregnancy. RESULTS: NSC showed a superior reproducibility in healthy volunteers with a low day-to-day variability as reflected by an intraclass correlation coefficient of 0.78. The receiver operating characteristic curve-estimated cutoff of 6.1 nmol/liter (0.22 microg/dl) demonstrated a sensitivity and specificity of 100% (area under the receiver operating characteristic curve, 1.0; 95% confidence interval, 0.94-1.0) in the diagnosis of CS. NSC, 24-h UFC [after adjusting the local laboratory cutoff to 504 nmol/d (183 microg/d)], and the urinary cortisol/creatinine ratio showed a tendency to be superior to 1 mg dexamethasone suppression test in correctly identifying CS. In late pregnancy, the preserved diurnal variation at a higher level of salivary cortisol reduced the specificity of NSC to 75%. CONCLUSION: Based on its remarkable reproducibility, easy noninvasive nature, and at least similar diagnostic performance, NSC appears to be a preferable alternative to 24-h UFC as a first-line screening test for CS. The cutoff values of NSC, 24-h UFC, and urinary cortisol/creatinine ratio have to be carefully adjusted using assay and center-specific reference ranges of sufficiently large populations.     

Elevated late-night salivary cortisol levels in elderly male type 2 diabetic veterans

OBJECTIVE: Late-night salivary cortisol (LNSC) is reportedly highly accurate for the diagnosis of Cushing's syndrome (CS). However, diagnostic thresholds for abnormal results are based on healthy, young populations and limited data are available on its use in elderly populations with chronic medical conditions. The purpose of this study was to evaluate LNSC levels in elderly male veterans with and without diabetes. DESIGN: Prospective evaluation of LNSC levels in male veterans. PATIENTS: One hundred and fifty-four participants with type 2 diabetes and 52 participants without diabetes. MEASUREMENTS: Participants underwent outpatient LNSC (2300 h) testing. Participants with elevated LNSC (> or = 4.3 nmol/l) underwent secondary testing, including 24-h urine free cortisol (24UFC, > 60 microg/day) and dexamethasone suppression testing (DST, serum cortisol > 50 nmol/l). Participants with positive secondary testing had a morning ACTH level analysed and either pituitary or adrenal imaging performed. RESULTS: One hundred and forty-one diabetics and 46 controls (mean age 61 years) returned samples (91% overall). Average LNSC levels (nmol/l) in diabetics were significantly higher than in nondiabetics [median (interquartile range): 2.6 (1.8-4.1) vs. 1.6 (1.0-2.0)] and in those aged > or = 60 compared to < 60 [2.7 (2.0-4.3) vs. 1.9 (1.4-2.9)] (P < 0.001 for both). Thirty-one participants required secondary testing. Seventy-nine per cent of participants who underwent secondary testing had normal 24UFC and DST. No cases of CS have been diagnosed to date. Increasing age [odds ratio (OR) 2.0 per decade], current diabetes mellitus (OR 4.4), and elevated blood pressure (OR 1.3 per 10 mmHg increase in systolic blood pressure) were associated with abnormal LNSC results (P < 0.05 for each). CONCLUSIONS: LNSC has been shown to be sensitive and specific in diagnosing CS in certain high-risk populations, primarily the young and middle-aged. The development of age- and comorbidity-adjusted thresholds may be warranted for LNSC testing in elderly subjects and in those with significant comorbidity.     

Cushing’s syndrome: diagnosis and surveillance using salivary cortisol

This short review summarizes the use of late-night salivary cortisol measurement in the diagnosis of Cushing’s syndrome, in the evaluation of patients with adrenal incidentalomas, and in monitoring of post-operative patients, with a focus on the different assay methodologies currently in common use. The focus is on recent studies identified by literature searches using Ovid Medline and Google Scholar as well as analysis of several recent review articles on the topic. Measurement of late night salivary cortisol (LNSC) has an excellent sensitivity and specificity for the diagnosis of Cushing’s syndrome regardless of the assay methodology used. Immunoassays have the advantage of simplicity, low cost, and small sample volume requirement, while liquid chromatography-tandem mass spectrometry has the advantage of a high specificity for cortisol and the ability to measure cortisone. The overnight dexamethasone suppression test appears to be superior to LNSC measurement in the evaluation of patients with adrenal incidentalomas. LNSC measurement is an excellent approach to monitor post-operative Cushing’s disease patients for surgical failure or recurrence. Salivary cortisol is most useful as the initial test when Cushing’s syndrome is suspected and for periodic patient monitoring after pituitary surgery for Cushing’s disease.     

The 4‐mg intravenous dexamethasone suppression test in the diagnosis of Cushing’s syndrome

Objective Optimal diagnostic criteria for the 4‐mg intravenous dexamethasone suppression test (IVDST) in patients with Cushing’s syndrome (CS), compared with normal subjects, have not been established. We evaluated the performance of the 4‐mg IVDST for differentiating CS from normal subjects and to define the responses in CS of various aetiologies. Design, subjects, measurements Thirty‐two control subjects [normal and overweight/obese participants with or without type 2 diabetes) were prospectively studied, and data from 66 patients with Cushing’s disease (CD), three with ectopic ACTH syndrome (EAS), 14 with adrenal Cushing’s (AC)] and 15 with low probability of CS (LPC) from three tertiary hospitals were retrospectively evaluated. Dexamethasone was infused at 1 mg/h for 4 h. Plasma cortisol and ACTH were measured at ?60 min (baseline), ?5 min, +3 h, +4 h, +5 h and at +23 and +23·5 h on Day 2. Results Control subjects (including those with type 2 diabetes) exhibited a marked suppression of cortisol which was maintained until Day 2. Two of 15 patients with LPC had Day 2 cortisol results that overlapped with CS. Patients with CD demonstrated partial suppression, with rebound hypercortisolism on Day 2. Patients with AC and EAS did not suppress cortisol levels. Day 2 cortisol level of >130 nmol/l (or >20% of the baseline) diagnosed CS with 100% sensitivity and 96% specificity. Conclusion While the IVDST allowed complete discrimination between control subjects and CS, 13% of LPC overlapped with CS. Given the small number of EAS, no conclusion can be drawn regarding the utility of this test in the differential diagnosis of CS.     

Diagnostic efficacy of midnight cortisol and midnight ACTH in the diagnosis and localisation of Cushing’s syndrome

Classical tests for diagnosis of Cushing’s syndrome (CS) like urine free cortisol and dexamethasone suppression tests have limitations in various clinical settings. This study evaluated the usefulness of sleeping midnight serum cortisol (SMNC) as a diagnostic test for hypercortisolemia. A simultaneously done midnight plasma ACTH level was used to classify the disease as ACTH dependent or independent. Standard biochemical tests, SMNC, midnight plasma ACTH and appropriate imaging evaluated patients with a clinical suspicion of Cushing’s syndrome. We evaluated 43 patients with CS comprising of 34 patients with Cushing’s disease (CD), 2 patients with thymic carcinoid producing ectopic CS, 5 patients with adrenal carcinoma and 2 with adrenal adenoma. Thirteen patients with clinical suspicion were also evaluated with the above tests and CS was ruled out. SMNC, midnight plasma ACTH and dexamethasone suppressed cortisol was collected from patients with a suspicion of CS. SMNC was evaluated against histopathology as the gold standard. SMNC achieved 100% sensitivity in the diagnosis of endogenous CS at cut offs of 138 nmol/l and below. Raising the cut off to 207 nmol/l resulted in a test sensitivity of 90.5%. At a cut off of 1.65 pmol/l, midnight plasma ACTH could distinguish ACTH independent causes of CS with 100% sensitivity. We concluded that a single midnight collection could identify all patients with CS and classify the ACTH status at the proposed cut offs.     

Diagnosis of adrenal insufficiency: Evaluation of the corticotropin-releasing hormone test and Basal serum cortisol in comparison to the insulin tolerance test in patients with hypothalamic-pituitary-adrenal disease

The aim of the study was to evaluate the diagnostic value of the human CRH test and the basal morning serum cortisol for the diagnosis of adrenal insufficiency. Putative peak cortisol cut points for the CRH test and basal cortisol cut points were determined by receiver operating characteristic (ROC) analysis with the insulin tolerance test as reference test. Fifty-four patients with suspected hypothalamic-pituitary-adrenal disease were tested. In 20 healthy controls, CRH led to a mean peak cortisol of 594.8 +/- 21.7 nmol/liter. The lower limit of a normal response was calculated as 400 nmol/liter. ROC analysis of peak cortisol levels during CRH testing of patients with suspected hypothalamic-pituitary-adrenal disease suggested an optimal peak cortisol cut point of < or 377 nmol/liter for the diagnosis of adrenal insufficiency and a 96% specificity but poor sensitivity of 76%. The baseline cortisol in the healthy control group showed a mean of 439.3 +/- 24.9 nmol/liter, resulting in a lower limit of 267 nmol/liter. ROC analysis of patients suggested the highest accuracy for basal cortisol levels of 285 nmol/liter or more for the diagnosis of adrenal insufficiency (100% sensitivity and 61% specificity). Within this patient group, a cortisol of more than 98 nmol/liter excluded adrenal insufficiency among those without the disorder, yielding 100% specificity. Using these criteria of upper (285 nmol/liter) and lower (98 nmol/liter) cut-off points with high sensitivity and specificity can reduce the number of individuals who need provocative tests. Basal cortisol is less expensive, and we therefore suggest to use it as a first-line test of adrenal insufficiency. Because of the low sensitivity of the human CRH test, we do not recommend it as a second test.     

Midnight salivary cortisol for the initial diagnosis of Cushing's syndrome of various causes

We assessed the value of midnight salivary cortisol for the initial diagnosis of Cushing's syndrome. Sixty-three patients with various causes of Cushing's syndrome (37 with Cushing's disease, 17 with adrenal Cushing's syndrome, and nine with ectopic ACTH syndrome) and 54 control subjects with simple obesity were studied. All patients with Cushing's syndrome excreted more than 90 microg urinary free cortisol (UFC)/d (248 nmol/d), and all controls excreted less than 90 microg/d UFC. All patients with Cushing's syndrome had a midnight salivary cortisol concentration above 2.0 ng/ml (5.52 nmol/liter), whereas only three controls did so [2.0 ng/ml (5.52 nmol/liter); 2.05 ng/ml (5.66 nmol/liter); and 3.6 ng/ml (9.96 nmol/liter)]. This cut-off provides a sensitivity of 100% and a specificity of 96%. In patients with Cushing's syndrome, midnight salivary cortisol concentrations were correlated with UFC collected over the same period of time (0800-0800 h). Salivary cortisol measurements taken every 4 h showed a typical lack of circadian variation. The daily measurement of midnight salivary cortisol concentrations for 2 wk or more in five other out-patients (with obvious Cushing's disease, subclinical adrenal Cushing's syndrome, suspected Cushing's syndrome, pituitary incidentaloma, and prolactinoma) demonstrated the clinical utility of this factor. Measuring midnight salivary cortisol is an easy and noninvasive means of diagnosing hypercortisolism. Its diagnostic accuracy is identical to, if not better than, that of previously described gold standards.     

The influence of the route of oestrogen administration on serum levels of cortisol-binding globulin and total cortisol

Objectives Oral oestrogen preparations increase total cortisol concentration by increasing circulating cortisol‐binding globulin (CBG) levels. Transdermal oestrogen treatments are being used increasingly in clinical practice. These topical preparations may have less of an effect on CBG and hence on total serum cortisol levels by reducing hepatic oestrogen exposure. The purpose of this study was to compare the effects of oral and topical oestrogen treatments on CBG, total serum cortisol and salivary cortisol levels. Design and Patients This was a single‐centre, cross‐sectional study of 37 women aged 33 ± 6 years (mean ± SD). Fourteen women were using oral oestrogen therapy, eight were using transdermal therapy and 15 were oestrogen‐naïve control subjects. Measurements Following a screening visit, the subjects attended the endocrine investigation unit following an overnight fast. Blood and salivary samples were taken from 0830 to 0930 h between days 10 and 18 of the menstrual cycle (where appropriate). Results Total serum cortisol concentrations were 67% higher in those receiving oral oestrogen when compared to control subjects (660·9 ± 89·9 vs. 395·4 ± 53·2 nmol/l, P < 0·001). Values in those receiving transdermal oestrogen (334·7 ± 72·0 nmol/l) were no different from the control group. CBG levels were higher in those on oral oestrogen therapy (110·9 ± 19·6 mg/l, P < 0·001) when compared with either those on transdermal oestrogen (51·0 ± 5·4 mg/l) or the control population (49·0 ± 11·8 mg/l). Similar salivary cortisol concentrations were recorded in the three groups (controls 13·8 ± 2·6 nmol/l, oral oestrogen 15·5 ± 2·6 nmol/l, transdermal oestrogen 15·7 ± 3·9 nmol/l). Conclusions Oral oestrogen‐containing preparations increase total cortisol levels by increasing circulating CBG concentration. These effects were not seen in patients using transdermal oestrogen replacement. Although further studies are indicated, it is probably unnecessary to routinely discontinue transdermal oestrogen replacement when performing an assessment of the hypothalamic–pituitary–adrenal (HPA) axis or evaluating adequacy of hydrocortisone replacement.     

Evaluation of adrenal function using the human corticotrophin-releasing hormone test, low dose Synacthen test and 9am cortisol level in children and adolescents with central adrenal insufficiency

Background The insulin tolerance test (ITT) has become less popular in paediatrics because of the risks associated with hypoglycaemia. Human corticotrophin‐releasing hormone (hCRH) test results correlate with the ITT and may be an acceptable method to test for central adrenal insufficiency (CAI). Simpler tests, such as the low dose Synacthen test (LDST) and 9am cortisol, have also been proposed. Objective To compare the ability of the hCRH test, LDST, 9am cortisol level and 24‐h cortisol profiles to diagnose CAI in a paediatric population. Design and setting A cross‐sectional study in a tertiary paediatric endocrine clinic. Participants Thirty‐one children and adolescents (aged 2·3–18·3 years) with CAI risk factors had an hCRH test, LDST, 9am cortisol and 24‐h cortisol profile performed. Results Of 23 patients with confirmed CAI (hCRH peak cortisol < 400 nmol/), 19 failed the LDST (peak cortisol < 267 nmol/l, i.e. 10th percentile for controls). Nineteen would have failed based on the 10th percentile cut point for 9am cortisol (< 140 nmol/l). Using receiver operating characteristic (ROC) curve coordinates, a 9am cortisol < 108 nmol/l was sensitive (83%) and specific (99%) for CAI. The 9am cortisol levels measured on two occasions were repeatable (94%) and correlated (r = 0·83, P = 0·01). All eight adrenally sufficient patients (hCRH peak cortisol ≥ 400 nmol/l) passed the LDST. Seven had normal 9am cortisol (≥ 140 nmol/l). The 24‐h cortisol area under the curve (AUC) for these patients was within the 10th–90th percentiles for control subjects’ AUC. The peak cortisol to hCRH and LDST were correlated (r = 0·88, P = 0·01), with no difference between the peaks (mean difference –5·3 nmol/l, P = 0·69). Conclusions In children with CAI risk factors, the diagnosis can be made if unstressed 9am cortisol is < 108 nmol/l. As cortisol levels > 381 nmol/l are highly suggestive of normal hypothalamic–pituitary–adrenal (HPA) function, stimulation testing need only be performed if 9am cortisol is 108–381 nmol/l. The LDST should be interpreted cautiously because mild CAI may be missed. When stimulation results are marginal, 24‐h cortisol profiles can provide reassurance of normal cortisol status.     

Salivary cortisol for screening of Cushing''s syndrome in children

OBJECTIVE: Cushing's syndrome (CS) is characterized by changes in diurnal cortisol variation and total or partial resistance to cortisol suppression by dexamethasone (DEX). Diagnosing CS is a challenge especially in childhood and requires differentiation from primary obesity. The aim was verify the efficacy of salivary cortisol in differentiating primary obesity from CS in children. SUBJECTS AND METHODS: We studied 11 patients with CS confirmed by standard laboratory investigation and surgical findings aged 1-16 years, and 21 age-matched primary obese controls. Salivary samples were collected at 0900 h, 2300 h, and after an overnight DEX suppression test (20 microg/kg up to 1 mg). Salivary cortisol was measured by RIA. RESULTS: Diurnal variation of salivary cortisol levels was observed in all controls, as opposed to only 5 of 11 patients with CS. Suppression of salivary cortisol was detected in all controls but in no CS patient after the overnight DEX test. Mean salivary cortisol levels were higher in the CS than in the control group both at 2300 hours and at 0900 hours after DEX but no difference was observed at 0900 hours of the first day. The sensitivity and specificity of salivary cortisol at 0900 h, 2300 hours and after-DEX in diagnosing CS were 27% and 95.2%, 100% and 95. 2%, and 100% and 95.2%, respectively. Sensitivity and specificity of 100% were obtained by combining the data for 2300 hours and after-DEX. CONCLUSION: The combination of salivary cortisol determination at 2300 hours and after-Dexamethasone is an easily performed and noninvasive method with high specificity and sensitivity for diagnosing Cushing's syndrome in children.     

Clinical insights into the safety and utility of the insulin tolerance test (ITT) in the assessment of the hypothalamo-pituitary-adrenal axis

Objective The insulin tolerance test (ITT) is the gold standard for assessing GH and cortisol production in pituitary disease. However, areas of uncertainty remain regarding its safety in older people, the optimal duration of the test and its performance in insulin resistant states. Whether basal cortisol concentration can reliably predict an adequate adrenal response to hypoglycaemia remains to be determined. Patients and design We performed a cross‐sectional retrospective examination of 197 consecutive patients (mean age 41·8 ± 16·4, range 13–76 years) with pituitary disease who underwent the ITT over 18 months. The standard intravenous insulin dose administered was 0·15 units/kg body weight. Patients with acromegaly or with type 2 diabetes received 0·2 units/kg; those with basal cortisol < 100 nmol/l received 0·1 units/kg. Results Adequate hypoglycaemia (nadir glucose < 2·2 mmol/l) was achieved in 87% of patients, amongst whom 17% did not achieve peak cortisol until 120 min. There were no significant adverse events, even in those ≥ 65 years. Of the 18 patients who had basal cortisol < 100 nmol/l, 78% achieved adequate hypoglycaemia; 29% of those had an adequate peak cortisol response ≥ 500 nmol/l. A receiver operating characteristics curve identified a basal cortisol of ≥ 393 nmol/l to predict a normal peak cortisol response to hypoglycaemia. Conclusions In specialized units, the ITT is safe even in elderly patients and those with hypocortisolaemia. The standard 90‐min. cut‐off for the ITT misses one in six peak cortisol responses. Some patients with basal cortisol < 100 nmol/l had a normal cortisol response to hypoglycaemia.     

Late-night salivary cortisol as a screening test for the diagnosis of Cushing's syndrome in Japan

Measurement of late-night and/or midnight salivary cortisol currently used in US and European countries is a simple and convenient screening test for the initial diagnosis of Cushing's syndrome (CS). Unfortunately, this test has not been widely used in Japan. The purpose of this study was to evaluate the usefulness of the measurement of late-night salivary cortisol as a screening test for the diagnosis of CS in Japan. We studied 27 patients with various causes of CS, consisting of ACTH-dependent Cushing's disease [5] and ectopic ACTH syndrome [4] and ACTH-independent adrenal CS [11] and subclinical CS [7]. Eleven patients with type 2 diabetes and obesity and 16 normal subjects served as control group. Saliva samples were collected at late-night (23:00) in a commercially available device and assayed for cortisol by radioimmunoassay. There were highly significant correlations (P<0.0001) between late-night serum and salivary cortisol levels in normal subjects (r = 0.861) and in patients with CS (r = 0.788). Late-night salivary cortisol levels in CS patients (0.975 +/- 1.56 microg/dl) were significantly higher than those in normal subjects (0.124 +/- 0.031 microg/dl) and in obese diabetic patients (0.146 +/- 0.043 microg/dl), respectively. Twenty-five out of 27 CS patients had late-night salivary cortisol concentrations greater than 0.21 microg/dl, whereas those in control group were less than 0.2 microg/dl. Receiver operating characteristic curve (ROC) analysis showed that the cut-off point of 0.21 microg/dl provides a sensitivity of 93% and a specificity of 100%. Therefore, it is concluded that the measurement of late-night salivary cortisol is an easy and reliable noninvasive screening test for the initial diagnosis of CS, especially useful for large high-risk populations, such as diabetes and obesity.     

库欣综合征筛查中不同剂量过夜地塞米松抑制试验诊断价值的比较

目的评价不同剂量（1 mg和2 mg）过夜地塞米松抑制试验（ODST）在库欣综合征筛查中的诊断价值,探究最佳筛查药物剂量和诊断切点,以提高临床工作中对该疾病的检出率,减少药物对人体可能造成的不良反应。 方法回顾性分析从2000年1月至2017年12月山东大学附属省立医院内分泌代谢病科收治并确诊的96例库欣综合征患者及61例临床怀疑经完善检查排除库欣综合征的患者的临床资料,在相同诊断切点下,比较不同剂量试验后血清皮质醇抑制程度及诊断敏感性、特异性;在相同剂量药物下,比较不同诊断切点在疾病筛查中的敏感性、特异性。 结果在1 mg过夜地塞米松抑制试验中,库欣综合征组皮质醇抑制率为17.9%,非库欣综合征组为78.7%;在2 mg过夜地塞米松抑制试验中,库欣综合征组皮质醇抑制率为24.2%,非库欣综合征组为87.2%。以试验当天8:00血清皮质醇为基础值,以次日8:00血清皮质醇<50 nmol/L（1.8 μg/dl）为库欣综合征诊断切点,1 mg ODST诊断库欣综合征的敏感性、特异性分别为为100%、42.8%;2 mg ODST诊断库欣综合征的敏感性及特异性分别为100%、69.7%;若以次日8:00血清皮质醇<138 nmol/L（5 μg/dl）为库欣综合征诊断切点,1 mg ODST诊断库欣综合征的敏感性、特异性分别为为100%、85.7%,2mg ODST诊断库欣综合征的敏感性、特异性为100%、93.9%。在库欣综合征的筛查中,在相同诊断切点下,2 mg ODST比1 mg ODST诊断结果更可靠;在相同剂量药物下,以次日8:00血清皮质醇<138 nmol/L（5 μg/dl）作为诊断切点,诊断敏感性无明显差别,特异性更高,诊断更准确。 结论综上所述,在库欣综合征筛查过程中,以次日8:00血清皮质醇<138 nmol/L（5 μg/dl）为库欣综合征诊断切点,进行2 mg ODST的诊断准确性明显提高,诊断结果更为可靠,值得在实践中推广应用。     

Performance of a third‐generation TSH‐receptor antibody in a UK clinic

Background UK national guidelines recommend the measurement of TSH receptor antibodies (TRAb) in certain clinical scenarios. A commercial third‐generation TRAb autoantibody M22‐biotin ELISA assay was introduced in May 2008 in our centre. Objective To evaluate the diagnostic performance of a TRAb assay in a retrospective and subsequently a prospective cohort in a UK centre. Design A retrospective review of patients with thyroid disease followed by a prospective observational study in consecutive patients with newly found suppressed serum thyrotrophin (TSH). Patients and Measurements Medical records of 200 consecutive patients with thyroid disorders who had TRAb measured since the introduction of the assay. In a prospective study 44 patients with newly identified hyperthyroidism (TSH < 0·02 mIU/l) had sera assayed for TRAb prior to their clinic appointment at which a final diagnosis was sought. Results In the retrospective cohort, the manufacturer’s cut‐off point of TRAb ≥0·4 U/l resulted in a positive predictive value (PPV) of 95%, sensitivity 85%, specificity 94% and negative predictive value (NVP) 79% to diagnose Graves’ disease using defined criteria. Receiver operating characteristic (ROC) analysis determined an optimal cut‐off point of TRAb ≥3·5 U/l with a 100% specificity to exclude patients without Graves’ disease at the cost though of a lower sensitivity (43%). In the prospective study, the sensitivity, PPV, specificity and NPV were all 96% using the ≥0·4 U/l cut‐off. When combining hyperthyroid patients from both cohorts the assay sensitivity and specificity at ≥0·4 U/l cut‐off were 95% and 92% respectively. A positive TRAb result increased the probability of Graves’ disease for a particular patient by 25–35% and only six (2·5%) patients had a diagnosis of hyperthyroidism of uncertain aetiology after TRAb testing. Conclusions The assay studied specifically identifies patients with Graves’ disease. It is a reliable tool in the initial clinical assessment to determine the aetiology of hyperthyroidism and has the potential for cost‐savings.     

Radioimmunoassay and tandem mass spectrometry measurement of bedtime salivary cortisol levels: a comparison of assays to establish hypercortisolism

CONTEXT: Although bedtime salivary cortisol measurement has been proposed as the optimal screening test for the diagnosis of Cushing's syndrome, its performance using commercially available assays has not been widely evaluated. OBJECTIVE: Our objective was to compare RIA and tandem mass spectrometry (LC-MS/MS) measurement of salivary cortisol in obese subjects and healthy volunteers. DESIGN AND SETTING: We conducted a cross-sectional prospective study of outpatients. SUBJECTS AND METHODS: We studied 261 obese subjects (186 female) with at least two additional features of Cushing's syndrome and 60 healthy volunteers (30 female). Subjects provided split bedtime salivary samples for cortisol measurement by commercially available RIA and LC-MS/MS. Results were considered normal or abnormal based on the laboratory reference range. Subjects with abnormal results underwent evaluation for Cushing's syndrome. RESULTS: In paired samples, RIA gave a lower specificity than LC-MS/MS in obese subjects (86 vs. 94%, P = 0.008) but not healthy volunteers (86 vs. 82%, P = 0.71). Among subjects with at least one abnormal result, both values were abnormal in 44% (confidence interval 26-62%) of obese and 75% (confidence interval 33-96%) of healthy volunteers. In obese subjects, salivary cortisol concentrations were less than 4.0 to 643 ng/dl (<0.11-17.7 nmol/liter; normal, < or =100 ng/dl, 2.80 nmol/liter) by LC-MS/MS and less than 50 to 2800 ng/dl (1.4-77.3 nmol/liter; normal, < or =170 ng/dl, 4.7 nmol/liter) by RIA. Cushing's syndrome was not diagnosed in any subject. CONCLUSION: Salivary cortisol levels should not be used as the sole test to diagnose Cushing's syndrome if laboratory-provided reference ranges are used for diagnostic interpretation.     

Accuracy of immunoassay and mass spectrometry urinary free cortisol in the diagnosis of Cushing’s syndrome

Purpose

Urinary free cortisol (UFC) determination by highly specific methods as mass spectrometry instead of commercially available antibody-based immunoassays is increasingly recommended. However, clinical comparisons of both analytical approaches in the screening of Cushing’s syndrome (CS) are not available. The aim of this study was to evaluate the diagnostic value of mass spectrometry versus immunoassay measurements of 24 h-UFC in the screening of CS.

Methods

Cross-sectional study of 33 histologically confirmed CS patients: 25 Cushing’s disease, 5 adrenal CS and 3 ectopic CS; 92 non-CS patients; and 35 healthy controls. UFC by immunoassay (UFCxIA) and mass spectrometry (UFCxMS), urinary free cortisone (UFCo) and UFC:UFCo ratio were measured, together with creatinine-corrected values. Sensitivity, specificity, AUC and Landis and Koch concordance index were determined.

Results

AUC for UFCxIA and UFCxMS were 0.77 (CI 0.68–0.87) and 0.77 (CI 0.67–0.87) respectively, with a kappa coefficient 0.60 and strong Landis and Koch concordance index. The best calculated cutoff values were 359 nmol/24 h for UFCxIA (78 % sensitivity, 62 % specificity) and 258.1 nmol/24 h for UCFxMS (53 % sensitivity, 86 % specificity). The upper limit of UFCxIA and UCFxMS reference ranges were 344.7 and 169.5 nmol/24 h respectively. Sensitivity and specificity for CS diagnosis at these cutpoints were 84 and 56 % for UFCxIA and 81 and 54 % for UFCxMS.

Conclusions

According to our data, both methods present a very similar diagnostic value. However, results suggest that lower cutoff points for mass spectrometry may be necessary in order to improve clinical sensitivity.