The Cushing syndrome: an update on diagnostic tests.

Area of Science:

• Endocrinology
• Diagnostic Medicine

Background:

• Cushing syndrome diagnosis requires reliable and accurate testing methods.
• Evaluating diagnostic test performance is crucial for clinical decision-making.

Purpose of the Study:

• To review and evaluate diagnostic tests for Cushing syndrome based on published reports since 1978.
• To assess the efficacy of various diagnostic modalities for Cushing syndrome.

Main Methods:

• Literature search of English-language studies from 1978-1989 using Index Medicus and bibliographies.
• Inclusion of studies with five or more patients; smaller studies and case reports were included if pertinent.
• Analysis of individual patient data for corticotropin-releasing hormone (CRH) stimulation test criteria.

Main Results:

• No single new test definitively surpasses existing diagnostic methods.
• The CRH stimulation test shows 91% sensitivity and 95% specificity for pituitary Cushing syndrome.
• Overnight high-dose dexamethasone suppression test demonstrates 89% sensitivity and 100% specificity.

Conclusions:

• 24-hour urine free cortisol and low-dose dexamethasone suppression remain primary diagnostic tools.
• CRH stimulation test serves as an outpatient option for etiological diagnosis.
• Magnetic resonance imaging (MRI) and inferior petrosal sinus sampling are valuable for specific diagnostic challenges.