Cushing's Syndrome: Screening and Diagnosis

Area of Science:

• Endocrinology
• Internal Medicine

Background:

• Endogenous Cushing's syndrome (CS) is a rare endocrine disorder with diverse clinical manifestations including hypertension, diabetes, and obesity.
• Increased diagnosis rates are attributed to improved screening and diagnostic strategies.

Purpose of the Study:

• To review and compare the diagnostic accuracy and practical considerations of key screening tests for endogenous Cushing's syndrome.
• To assist clinicians in selecting the most appropriate test for diagnosing hypercortisolism.

Main Methods:

• The review summarizes recent literature on the 1-mg dexamethasone suppression test (1-mg DST), late night salivary cortisol (LNSC), and 24-hour urinary free cortisol (UFC).
• It discusses the biochemical principles, procedural aspects, and potential limitations of each screening method.
• Comparison includes diagnostic accuracy, ease of use for outpatients, and interference factors.

Main Results:

• All three recommended screening tests (1-mg DST, LNSC, UFC) have established roles in diagnosing CS.
• Each test presents unique challenges, such as drug interference with 1-mg DST, potential false results with LNSC, and collection variability with UFC.
• Advances in mass spectrometry offer improved specificity over traditional immunoassays.

Conclusions:

• The choice of screening test for endogenous CS depends on clinical context, patient factors, and laboratory capabilities.
• Understanding the nuances of each test is crucial for accurate diagnosis and effective management of hypercortisolism.
• Physicians should consider test limitations and recent technological advancements when selecting a diagnostic strategy.