[Comparing overnight dexamethasone suppression test, urine free cortisol, and midnight serum cortisol for the initial diagnosis of Cushing' s syndrome].

[cushing syndrome]

To identify retrospectively the optimal cut-off points and the values of overnight dexamethasone suppression test , urine free cortisol , and midnight serum cortisol in the initial diagnosis of Cushing 's syndrome in Chinese people .The results of overnight low -dose dexamethasone suppression test (PTC-DST ), urine free cortisol (UFC ) and late -night plasma total cortisol (PTC-24 h ) of 102 patients who had clinically confirmed Cushing 's syndrome and 102 patients without Cushing 's syndrome were extracted from West China Hospital . Receiver operating characteristic (ROC ) curves were drawn to identify optimal cut-off points of the three assays and their values in diagnosing Cushing ' s syndrome .The optimal cut-off point (the point on the ROC curve closest to 1 ) for PTC-DST was set at 86 nmol /L , with 98 . 7 % sensitivity and 97 . 2 % specificity (100 % sensitivity and 94 . 4 % specificity was achieved at 50 nmol /L 100 %o sensitivity and 95 . 8 % specificity was achieved at 60 nmol /L ). The optimal cut-off point for PTC-24 h was set at 347 nmol /L , with 93 . 4 % sensitivity and 98 . 4 % specificity (98 . 9 % sensitivity and 85 . 2 % specificity was achieved at 207 nmol /L ). The optimal cut-off point for UFC was set at 230 . 15 icrog /24 h , with 92 . 2 sensitivity and 95 . 7 % specificity (96 . 1 % sensitivity and 85 . 1 % specificity was achieved at 127 . 55 microg /24 h ). There was no significant difference between PTC-DST and PTC-24 h in the areas under the ROC curves , whereas both had a greater area under the ROC curve than that of UFC (P < 0 . 05 ).Compared with the recommended 50 nmol /L cut-off point for PTC-DST in the USA and the European countries , the same sensitivity and a higher specificity can be achieved at a cut-off at 60 nmol /L for the Chinese people . PTC-DST and PTC-24 h have similar values in the initial diagnosis of Cushing 's syndrome , but PTC-DST is more convenient to be used in outpatient environment .

Diseases
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Diseases presenting "overnight low-dose dexamethasone suppression test" symptom

cushing syndrome

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