Screening Test For Cushing's Syndrome Research Articles

Late-night salivary cortisol cut-offs for diagnosis of Cushing syndrome using second-generation electrochemiluminescence immunoassay kits.

Late-night salivary cortisol (LNSC) is a simple and reliable screening test for Cushing syndrome (CS). With improved analytical performance of the current second-generation electrochemiluminescence immunoassay (ECLIA; Elecsys Cortisol-II; Roche Diagnostics), there is a need to revisit the LNSC cut-offs, especially in a South-Asian population. To derive LNSC cut-offs for diagnosis of CS using second-generation ECLIA kits. Diagnostic accuracy study. We prospectively recruited 155 controls aged 18-60 years, including, normal-weight (body mass index [BMI] < 25 kg/m2 and no hypertension or diabetes [n = 53]) and overweight/obese (BMI 25-30 kg/m2 and hypertension and/or diabetes [n = 52] or BMI ≥ 30 kg/m2 with/without comorbidities [n = 50]) participants. All participants submitted LNSC samples collected at home; overweight/obese controls additionally underwent dexamethasone suppression test to exclude CS. We also reviewed records of adults with endogenous CS (cases, n = 92) and a valid LNSC result using the same method. The 95th percentile for LNSC in controls was 6.76 nmol/L. The mean ± SD LNSC levels were 40.47 ± 49.63 nmol/L in cases and 3.37 ± 1.18 nmol/L in controls (p < 0.001). Receiver operating characteristic (ROC) analysis showed excellent diagnostic performance of LNSC for CS, with area under curves (AUCs) of 0.994 (cases vs. all controls) and 0.993 (cases vs. overweight/obese controls), respectively. The best diagnostic performance was achieved at cut-offs ≥6.73 nmol/L (sensitivity: 97.8%, specificity: 94.8%) and ≥7.26 nmol/L (sensitivity: 97.8%, specificity: 95.1%), respectively. LNSC measured using second-generation ECLIA demonstrated high diagnostic accuracy for CS. Based on this study, we propose a LNSC cutoff ≥6.73 nmol/L to diagnose CS.

Bedtime Salivary Cortisol as a Screening Test for Cushing Syndrome in Children.

BackgroundDiagnosing Cushing syndrome (CS) can be challenging. The 24-hour urine free cortisol (UFC) measurement is considered gold standard. This is a laborious test, dependent on correct urine collection. Late-night salivary cortisol is easier and is used as a screening test for CS in adults, but has not been validated for use in children.ObjectiveTo define liquid chromatography tandem mass spectrometry (LC-MS/MS)-based cutoff values for bedtime and morning salivary cortisol and cortisone in children, and validate the results in children with and without CS.MethodsBedtime and morning salivary samples were collected from 320 healthy children aged 4 to 16 years. Fifty-four patients from the children’s outpatient obesity clinic and 3 children with pituitary CS were used for validation. Steroid hormones were assayed by LC-MS/MS. Cutoff levels for bedtime salivary cortisol and cortisone were defined by the 97.5% percentile in healthy subjects.ResultsBedtime cutoff levels for cortisol and cortisone were 2.4 and 12.0 nmol/L, respectively. Applying these cutoff levels on the verification cohort, 1 child from the obesity clinic had bedtime salivary cortisol exceeding the defined cutoff level, but normal salivary cortisone. All 3 children with pituitary CS had salivary cortisol and cortisone far above the defined bedtime cutoff levels. Healthy subjects showed a significant decrease in salivary cortisol from early morning to bedtime.ConclusionsWe propose that bedtime salivary cortisol measured by LC-MS/MS with a diagnostic threshold above 2.4 nmol/L can be applied as a screening test for CS in children. Age- and gender-specific cutoff levels are not needed.

Prospective Evaluation of Late-Night Salivary Cortisol and Cortisone by EIA and LC-MS/MS in Suspected Cushing Syndrome.

ContextLate-night salivary cortisol (LNSC) measured by enzyme immunoassay (EIA-F) is a first-line screening test for Cushing syndrome (CS) with a reported sensitivity and specificity of >90%. However, liquid chromatography-tandem mass spectrometry, validated to measure salivary cortisol (LCMS-F) and cortisone (LCMS-E), has been proposed to be superior diagnostically.Objective, Setting, and Main Outcome MeasuresProspectively evaluate the diagnostic performance of EIA-F, LCMS-F, and LCMS-E in 1453 consecutive late-night saliva samples from 705 patients with suspected CS.DesignPatients grouped by the presence or absence of at least one elevated salivary steroid result and then subdivided by diagnosis.ResultsWe identified 283 patients with at least one elevated salivary result; 45 had an established diagnosis of neoplastic hypercortisolism (CS) for which EIA-F had a very high sensitivity (97.5%). LCMS-F and LCMS-E had lower sensitivity but higher specificity than EIA-F. EIA-F had poor sensitivity (31.3%) for adrenocorticotropic hormone (ACTH)-independent CS (5 patients with at least 1 and 11 without any elevated salivary result). In patients with Cushing disease (CD), most nonelevated LCMS-F results were in patients with persistent/recurrent CD; their EIA-F levels were lower than in patients with newly diagnosed CD.ConclusionsSince the majority of patients with ≥1 elevated late-night salivary cortisol or cortisone result did not have CS, a single elevated level has poor specificity and positive predictive value. LNSC measured by EIA is a sensitive test for ACTH-dependent Cushing syndrome but not for ACTH-independent CS. We suggest that neither LCMS-F nor LCMS-E improves the sensitivity of late-night EIA-F for CS.

Late-Night Salivary Cortisol in Healthy, Community-Dwelling Asian Indians Assessed by Second-Generation ECLIA.

Late-night salivary cortisol (LNSC) is used as a screening test for Cushing syndrome (CS), but there is no community-derived normative data for the normal upper limit in the South Asian population. This study aimed to determine the upper limit of normal (97.5th percentile) for LNSC in an Asian Indian population using a commercially available second-generation electrochemiluminiscence immunoassay (ECLIA). LNSC in apparently healthy community-dwelling individuals was assessed by multistage cluster sampling. Healthy individuals age 18 to 60 years from 8 urban and 8 rural clusters of Thiruvananthapuram district were studied. Thirty people from an approximate population of 1000 individuals from each cluster participated in the study. A saliva sample was collected between 11 PM and 12 midnight and analyzed using Roche COBAS-e-411 and ultrasensitive Cortisol II kits the next day. Cortisol values from 474 salivary samples were available for final analysis after exclusion of improperly collected samples. The 97.5th percentile of the LNSC concentrations was 0.25 μg/dL (6.89 nmol/L) (90% CI, 0.23-0.27 μg/dL; ie, 6.34-7.45 nmol/L). In postmenopausal women, median LNSC was significantly higher but the 90% CI for the upper limit of their LNSC (0.28μg/dL or 7.72 nmol/L) overlapped with that of premenopausal women. This study establishes the normal value of LNSC estimated by second-generation ECLIA in healthy community-dwelling Asian Indian individuals for the first time. Salivary cortisol at 11 pm to 12 am is less than 0.25μg/dL (6.89 nmol/L) in the general Asian Indian population. Menopause causes a significant increase in LNSC and may lead to overdiagnosis of CS if not interpreted carefully.

Utility of a Single Late-Night Plasma Cortisol and Acth for the Diagnosis of Cushing Syndrome

To evaluate the diagnostic efficacy of various screening tests for the diagnosis of Cushing syndrome (CS). Thirty-five patients with CS and 16 patients of pseudo-CS were enrolled. Assessment of 24-h urinary free cortisol (UFC), late-night salivary cortisol (LNSC), overnight dexamethasone suppression test (ONDST), late-night plasma cortisol (LNPC), and adrenocorticotropic hormone (ACTH) on outpatient basis, and during sleep as well as in awake state after 48 hours of hospital admission. We found that 24-h UFC performed the best among the screening tests with sensitivity, specificity and areas under the curve (AUCs) of 96.0%, 99%, and 0.988, respectively, at a cut-off of 144.6 μg/24 h. A cut-off of 10.5 nmol/L for LNSC had sensitivity 85.7%, specificity 88.2%, and an AUC of 0.897. A cut-off of 412.4 nmol/L for LNPC on outpatient basis had sensitivity 88.2%, specificity 91.2%, and an AUC of 0.957. Cut-offs of 215 and 243.3 nmol/L for LNPC during sleep and awake states after acclimatization had sensitivity, specificity, and an AUC of 94.1%, 88.2%, and 0.958, respectively. An ONDST cut-off of 94.6 nmol/L provided sensitivity, specificity, and an AUC of 96.0%, 99.03% and 0.995, respectively. A cut-off of 30.3 pg/mL for late-night ACTH on outpatient basis had sensitivity 67.6%, specificity 99.9%, and an AUC 0.796.A cut-off of 22.6 pg/mL for ACTH during sleep state after acclimatization had sensitivity, specificity, and an AUC of 73.5%, 99.2%, and 0.827, respectively. UFC is the best screening test for CS. Furthermore, single measurements of LNPC and ACTH help to establish the diagnosis and ACTH dependency of CS in the majority of patients with CS. ACTH = adrenocorticotropic hormone AUC = area under the curve CRH = corticotropin-releasing hormone CS = Cushing syndrome ECLIA = electrochemiluminescence immuno-assay LDDST = low-dose dexamethasone suppression test LNPC = late-night plasma cortisol LNSC = late-night salivary cortisol ONDST = overnight dexamethasone suppression test RIA = radio-immuno assay UFC = urinary free cortisol.

Cushing's Syndrome: Screening and Diagnosis.

Endogenous Cushing's syndrome (CS) is a rare disease, and usually characterized by hypertension, diabetes, obesity, osteoporosis, facial rounding, dorsocervical fat pad, thin skin, purple striae, hirsutism, and mood disorders. Efficient diagnostic and screening strategies lead to the diagnosis of a significantly higher number of cases of CS. As a screening test for CS, the Endocrine Society's Clinical Practice Guidelines recommend a single test with a high diagnostic accuracy, among the 1-mg dexamethasone suppression test (1-mg DST), late night salivary cortisol (LNSC), and 24h urinary free cortisol (UFC). In normal subjects, administering a higher than physiological dose of glucocorticoids prompts the suppression of cortisol secretion. The 1-mg DST explores this normal feedback reaction from the hypothalamic-pituitary-adrenal axis (HPA). It is a simple dynamic test, usually performed in outpatients. A morning serum cortisol level <50nmol/L suffices to exclude CS, unless there is a strong clinical suspicion to suggest otherwise. The HPA axis reaches a nadir just after a person has fallen asleep, but its circadian rhythm is impaired in CS patients, who feature higher cortisol values at night, which are easy to measure in saliva (the LNSC assay). Saliva collection is also suitable for outpatients since cortisol is stable at room temperature and the collection device can be mailed to the laboratory for analysis. UFC levels reflect the integrated tissue exposure to free cortisol over 24h, and thus provide a particular picture of endogenous hypercortisolism. In most cases, high UFC levels coincide with severe hypercortisolism. UFC is used not only to diagnose CS, but also to monitor its response to medical treatment. All screening tests have procedural snares: some drugs can interfere with the DST; false-positive or false-negative LNSC results may be due to an inadequate soaking of the device or to cyclic CS; and in the case of UFC it is important to ensure that patients provide complete urine collections with appropriate total volumes. Measuring cortisol with antibody-based immunoassays can also generate false-positive results due to cross-reactivity between cortisol, cortisone and other metabolites. Structurally-based assays, such as liquid chromatography with tandem mass spectrometry, only measure cortisol and have only recently become available for use in routine clinical practice. This review summarizes the recent literature on the clinical and biochemical aspects of CS diagnostics with a view to helping physicians choose the best screening test for diagnosing endogenous hypercortisolism.

Night-time salivary cortisol is an excellent screening test for Cushing syndrome

Night-time salivary cortisol is an excellent screening test for Cushing syndrome

Hydrocortisone Suppression Test for Cushing Syndrome

To develop a reliable suppression test for corticotropin (adrenocorticotrophic hormone, ACTH) for use in patients receiving anticonvulsant drugs, we selected hydrocortisone suppression of plasma corticosterone (B), whose secretion is regulated by corticotropin, thus eliminating the drug interference observed with the dexamethasone suppression test. By estimating an 8 AM base line plasma B concentration and administering 50 mg of hydrocortisone orally at midnight, we could evaluate its effect on plasma B suppression the following morning at 8 AM. The overnight suppression tests with 1 mg of dexamethasone and 50 mg of hydrocortisone reduced the plasma B concentration to less than 50% of the base line value and to less than 120 ng/deciliter in control subjects, but they failed to result in suppression in patients with Cushing syndrome. The 1-mg dose of dexamethasone caused no suppression in patients treated with anticonvulsants, whereas following hydrocortisone, base line plasma concentrations were reduced by more than 50%. The test appears to be as reliable a screening test for Cushing syndrome in drug-treated patients as the overnight dexamethasone suppression test is in patients not receiving drugs.