Searchable abstracts of presentations at key conferences in endocrinology
Endocrine Abstracts (2015) 37 GP02.07 | DOI: 10.1530/endoabs.37.GP.02.07

ECE2015 Guided Posters Adrenal (1) (8 abstracts)

Urinary free cortisone as a potential biomarker in diagnosing patients with mild Cushing's syndrome

Laura Trementino , Carolina Concettoni , Marianna Martino , Giorgia Marcelli , Grazia Michetti , Marco Boscaro & Giorgio Arnaldi

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1Division of Endocrinology, Polytechnic University of Marche, Ancona, Italy; 2Endocrinology Unit, Department of Medicine DIMED, University Hospital of Padua, Padua, Italy.


Introduction: Urinary free cortisol (UFC) determination has suboptimal sensitivity (SE) and specificity (SP) especially in mild Cushing’s syndrome (CS).

Aim: To determine the performance of UFC and its metabolite cortisone (UFE) measured using accurate assays such as HPLC and LC–MS/MS in diagnosing patients with CS.

Patients and methods: Sixty-seven patients with CS were compared to 49 sex- and age-matched non-CS. UFF and UFE levels were assessed by HPLC until 2009 and afterwards by LC–MS/MS. The mean value of two 24-h urine collections was used for the analysis. SE and SP were calculated at different cut-off values using ROC curve analysis.

Results: UFF and UFE values were significantly higher in patients with CS. However, the diagnostic performance of UFF by HPLC was low with 75.8% SE and 81.1% SP (cut-off value >33.9 μg/24 h). The performance of UFF by LC–MS/MS was 88.2% SE and 91.2% SP (cut-off value >47.4 μg/24 h). The performance of UFE was better than UFF by both assays. UFE by LC–MS/MS showed 97.1% SE and 91.7 SP% using a cut-off value >88.7 μg/24 h. When CS patients were stratified according to disease severity, UFE by LC–MS/MS showed a good diagnostic profile also in mild CS (UFF <2× ULN) with 92.3% SE and 91.7% SP (cut-off value >88.7 μg/24 h). Conversely, the performance of UFF in mild CS was low (84.6% SE and 75% SP; cut-off value >44.2). UFF and UFE showed an optimal diagnostic performance with 100% SE and 100% SP in moderate to severe CS (UFF ≥2× ULN). The performance of urinary steroids was not different according to age, sex, disease aetiology, and disease status in CS.

Conclusions: UFE measured by LC–MS/MS seems to be a new and good biomarker in diagnosing CS especially in patients with mild hypercortisolism at higher risk for misdiagnosis with UFF.

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