Objective Cushing’s syndrome (CS), when fully expressed, is easily diagnosed. Mild cases, however, may require careful distinction from pseudo-Cushing’s states as may occur in depression, alcoholism, polycystic ovary disease and visceral obesity. The aim of the present study is a reappraisal of the diagnostic accuracy of the two tests most commonly used to differentiate CS from pseudo-Cushing’s: corticotropinreleasing hormone (CRH) stimulation after low dose dexamethasone administration and desmopressin stimulation. Design The study population comprised 32 patients with CS and 23 with pseudo-Cushing’s evaluated retrospectively. Methods Urinary free cortisol (UFC), serum cortisol at midnight and after low dose dexamethasone (1 mg overnight and 2 mg over two days) were measured. Further, patients were tested with dexamethasone + CRH and desmopressin and the diagnostic performances of the two tests were compared in the entire series as well as in patients with mild hypercortisolism only (i.e. UFC < 690 nmol/24 h). Results As expected, measurement of UFC, assessment of cortisol rhythmicity and inhibition after 1 mg/2 mg dexamethasone failed to clearly classify patients with pseudo-Cushing’s. Administration of CRH following 2-mg dexamethasone achieved 100% sensitivity but 62·5% specificity. Conversely, desmopressin testing correctly classified all but two patients with pseudo-Cushing’s (90% specificity) with 81·5% sensitivity. Diagnostic accuracy was comparable in the subgroup with mild hypercortisolism (21 CS, all 23 pseudo-Cushing’s patients). Desmopressin offered an incremental diagnostic effectiveness of 35·8/million inhabitants compared with dexamethasone + CRH as a second-line test. Conclusions Neither of the two tests guarantees absolute diagnostic accuracy. The specificity of dexamethasone + CRH is less brilliant than previously reported and appears to be inferior to desmopressin stimulation. The greatest diagnostic effectiveness results from the low-dose dexamethasone test combined with the desmopressin test. Skilful use of dynamic testing and balanced clinical judgement are necessary to distinguish between Cushing’s syndrome and pseudo-Cushing’s.

The dexamethasone-suppressed corticotropin-releasing hormone stimulation test and the desmoppression test to distinguish : Cushing's syndrome from pseudoCushing states / F. Pecori Giraldi, R. Pivonello, A.G. Ambrogio, M.C. De Martino, M. De Martin, M. Scacchi, A. Colao, P.M. Toja, G. Lombardi, F. Cavagnini. - In: CLINICAL ENDOCRINOLOGY. - ISSN 0300-0664. - 66:2(2007), pp. 251-257.

The dexamethasone-suppressed corticotropin-releasing hormone stimulation test and the desmoppression test to distinguish : Cushing's syndrome from pseudoCushing states

F. Pecori Giraldi
Primo
;
A.G. Ambrogio;M. Scacchi;F. Cavagnini
Ultimo
2007

Abstract

Objective Cushing’s syndrome (CS), when fully expressed, is easily diagnosed. Mild cases, however, may require careful distinction from pseudo-Cushing’s states as may occur in depression, alcoholism, polycystic ovary disease and visceral obesity. The aim of the present study is a reappraisal of the diagnostic accuracy of the two tests most commonly used to differentiate CS from pseudo-Cushing’s: corticotropinreleasing hormone (CRH) stimulation after low dose dexamethasone administration and desmopressin stimulation. Design The study population comprised 32 patients with CS and 23 with pseudo-Cushing’s evaluated retrospectively. Methods Urinary free cortisol (UFC), serum cortisol at midnight and after low dose dexamethasone (1 mg overnight and 2 mg over two days) were measured. Further, patients were tested with dexamethasone + CRH and desmopressin and the diagnostic performances of the two tests were compared in the entire series as well as in patients with mild hypercortisolism only (i.e. UFC < 690 nmol/24 h). Results As expected, measurement of UFC, assessment of cortisol rhythmicity and inhibition after 1 mg/2 mg dexamethasone failed to clearly classify patients with pseudo-Cushing’s. Administration of CRH following 2-mg dexamethasone achieved 100% sensitivity but 62·5% specificity. Conversely, desmopressin testing correctly classified all but two patients with pseudo-Cushing’s (90% specificity) with 81·5% sensitivity. Diagnostic accuracy was comparable in the subgroup with mild hypercortisolism (21 CS, all 23 pseudo-Cushing’s patients). Desmopressin offered an incremental diagnostic effectiveness of 35·8/million inhabitants compared with dexamethasone + CRH as a second-line test. Conclusions Neither of the two tests guarantees absolute diagnostic accuracy. The specificity of dexamethasone + CRH is less brilliant than previously reported and appears to be inferior to desmopressin stimulation. The greatest diagnostic effectiveness results from the low-dose dexamethasone test combined with the desmopressin test. Skilful use of dynamic testing and balanced clinical judgement are necessary to distinguish between Cushing’s syndrome and pseudo-Cushing’s.
Settore MED/13 - Endocrinologia
2007
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/39495
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