| ObjectivesThe overnight dexamethasone suppression test is currently the commonly used Cushing s syndrome screening test.Due to the lack of large-scale epidemiological data in China,the current guidelines have developed screening standards based on European data,and recommended research centers according to their own experiments.Method and data to develop appropriate standards.At present,the diagnosis of cut-point and dexamethasone dose is still controversial.The purpose of this study was to investigate the optimal dexamethasone dose and ODST diagnostic cut-off point,and to clarify the diagnostic value of different diagnostic cut points and different doses(1 mg and 2 mg)in Cushing s syndrome screening.Improve the detection rate of the disease in clinical work,reduce the possible adverse effects of drugs on the human body and avoid increasing the medical expenses of patients.Methods1.Confirmed Cushing s syndrome population:retrospective analysis of clinical data of patients with Cushing s syndrome diagnosed by the Department of Endocrinology,Shandong Provincial Hospital from January 2005 to January 2017,comparing different doses(1 mg and 2 mg)of the ground The degree of serum cortisol inhibition after the inhibition of the test was observed,and the accuracy of different doses of dexamethasone at different diagnostic cut points was observed.2.People with non-Cushing’s syndrome(such as obesity,diabetes,hypertension,etc.with elevated cortisol but excluding Cushing s syndrome:elevated cerebral plasma cortisol or loss of circadian rhythm in clinical work Patients were randomized to receive 1 mg and 2 mg dexamethasone at midnight to observe the degree of serum cortisol inhibition after different doses of dexamethasone inhibition test,and to compare different doses of dexamethasone at different diagnostic cut points.In the accuracy.If a patient is diagnosed with Cushing s syndrome by follow-up examination or follow-up,it is removed from the analysis.3.Carry out a summary analysis of the data,through the sensitivity and specificity analysis,establish a diagnostic cut-point and dexamethasone dose suitable for the center,the laboratory,reduce missed diagnosis and misdiagnosis,and provide reference for clinical work.Resu ts1.Based on serum cortisol at 8:00 on the day of the test,serum cortisol<50 nmol/L(1.8 μg/dl)was used as the diagnostic cut-off point for Cushing s syndrome at 8:00 the next day,and 1 mg ODST was used to diagnose Cushing.The sensitivity and specificity of the syndrome were 100%and 53.3%,respectively,and the diagnostic accuracy was 78.8%.The sensitivity and specificity of the 2 mg ODST diagnosis of Cushing s syndrome were 100%and 78.9%,and the diagnostic accuracy was 92.5%..2.Serum cortisol<138 nmol/L(5 μg/dl)was used as the diagnostic cut-off point for Cushing’s syndrome at 8:00 the next day.The sensitivity and specificity of 1 mg ODST for the diagnosis of Cushing’s syndrome were 100%.93.3%,the diagnostic accuracy was 97.0%,the sensitivity and specificity of 2mg ODST diagnosis of Cushing s syndrome were 97.1%,100%,and the diagnostic accuracy was 98.1%.3.We used the same diagnostic cut-off point and different doses of dexamethasone to analyze the sensitivity of 2 mg ODST when<50 nmol/L(1.8 μg/dl)was used as the diagnostic cut-off point for Cushing s syndrome.There was no significant difference compared with 1 mg ODST,but the specificity was significantly improved.When<138 nmol/L(5 μg/dl)was used as the diagnostic cut-off point for Cushing’s syndrome,the diagnostic sensitivity of 2 mg ODST was compared with 1 mg ODST.There was a slight decrease,but the specificity was higher than 1 mg ODST;therefore,under the same diagnostic cut-off point,the diagnostic sensitivity of 2 mg ODST was not significantly decreased and the specificity was improved compared with 1 mg ODST.4.We performed the following analysis of the same dexamethasone dose and different diagnostic cut points:in 1 mg ODST,the sensitivity at<50 nmol/L(1.8 μg/dl)as the diagnostic cut point is equivalent to<138 nmol/L(5 μg/dl)was used as the diagnostic cut-off point,but the specificity was significantly reduced.In the 2 mg ODST,the sensitivity at<50 nmol/L(1.8 μg/dl)was used as the diagnostic cut-off point.Higher than<138 nmol/L(5 μg/dl)as the diagnostic cut-off point,but the specificity was significantly lower than 2 mg ODST;therefore,when the same dose of dexamethasone was given,<138 nmol/L(5 μg/dl)There was no significant decrease in the sensitivity of the diagnostic diagnosis of Cushing’s syndrome,and the specificity was improved.5.In the 1 mg ODST screening,in the Cushing syndrome group,the percentage of non-repressed cortisol in the next day at<50 nmol/L(1.8 μg/dl)was 100%,to<138 Nmol/L(5 μg/dl)was 100%of the number of unrecognized cortisol in the next day of diagnosis.In patients with non-Cushing syndrome,<50 nmol/L(1.8 μg/dl)was used as the diagnosis.The percentage of unrepressed cortisol in the next day was 46.7%,and the percentage of non-repressed cortisol in the next day at<138 nmol/L(5 μg/dl)was 6.7%.At 1 mg ODST,the percentage of unrecognized cortisol was lower at<138 nmol/L(5 μg/dl)for the next day.6.When using 2 mg ODST screening,the percentage of unconfirmed cortisol in the next day at<50 nmol/L(1.8 μg/dl)in the Cushing syndrome group was 100%,to<138 Nmol/L(5 μg/dl)was 97.1%of the number of non-repressed cortisols in the next day of diagnosis.In patients with non-Cushing syndrome,<50 nmol/L(1.8 μg/dl)was used as the diagnosis.The percentage of unrepressed cortisol in the next day was 21.1%,and the percentage of non-repressed cortisol in the next day at<138 nmol/L(5 μg/dl)was 0%.At 2 mg ODST,the percentage of unrecognized cortisol was lower at<138 nmol/L(5 μg/dl)for the next day.7.In the Cushing s syndrome group,1 mg and 2 mg overnight dexamethasone inhibition test with<50 nmol/L(1.8 μg/dl)as the diagnostic cut-off point and<138 nmol/L(5 μg/dl)There was no significant difference in the percentage of non-repressed cortisol in the next day.In the non-Cushing syndrome group,with<50 nmol/L(1.8 μg/dl)as the diagnostic cut-off point,the percentage of non-repressed 2 mg ODST cortisol was 21.1%,which was significantly lower than that of 1 mg ODST 46.7.%;When<138 nmol/L(5 μg/dl)was used as the diagnostic cut-off point,the percentage of non-repressed 2 mg ODST cortisol was 0%,which was also lower than 6.7%of 1 mg ODST.Therefore,in the initial screening of Cushing s syndrome,the percentage of uninhibited cortisol in 2 mg ODST was lower.Conclusions1.With the advancement of science and technology,the early screening methods of Cushing s syndrome are more and more perfect,but the current low-dose overnight dexamethasone suppression test is still the first choice for the initial screening of Cushing s syndrome.2.In the screening process of Cushing s syndrome,the serum cortisol<138 nmol/L(5 μg/dl)was used as the diagnostic cut-off point at 8:00 the next day,and the 2 mg low-dose dexamethasone inhibition test was performed to diagnose the sensitivity.No significant reduction was observed and specificity was increased,but further prospective studies were needed to validate.3.At present,there is no one method with 100%sensitivity and specificity.Therefore,in the diagnosis and differential diagnosis of Cushing s syndrome,we should carefully analyze the results of various tests and make a comprehensive judgment based on clinical manifestations. |
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