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Endocrine Abstracts (2023) 90 OC3.5 | DOI: 10.1530/endoabs.90.OC3.5

ECE2023 Oral Communications Oral Communications 3: Pituitary and Neuroendocrinology 1 (6 abstracts)

Interest of serum and salivary cortisol diurnal cycle in the positive diagnostic of Cushing syndrome and in the differential diagnosis of pseudo-Cushing syndrome

Bonnet Fideline 1,2,3 , Jonathan Poirier 4 , Ralph El Khoury 4 , Christelle Laguillier-Morizot 2,3 , Marie-Clémence Leguy 2 , Louis Thomeret 1,3 , Lucas Bouys 1,3,4 , Laurence Guignat 4 , Guillaume Assié 1,3,4 , Lionel Groussin 1,3,4 , Jean Guibourdenche 2,3 & Jerome Bertherat 1,3,4

1Cochin Institute, Inserm U1016-CNRS UMR8104, Paris, France; 2Cochin Hospital, Hormonology, Paris, France; 3Paris Cité University, Paris, France; 4Cochin Hospital, Endocrinology, Paris, France

Introduction: Biological diagnosis of Cushing syndrome relies on three parameters: 24 hours-free urinary cortisol; serum cortisol after 1 mg dexamethasone suppression test; late-night serum or salivary cortisol. These tests allow the diagnosis of cortisol excess but do not help in etiological diagnosis, particularly in the distinction between pseudo-Cushing and ACTH-dependent Cushing syndrome, which is often challenging. The aim of this study was to evaluate the performances of cortisol diurnal cycle in serum and saliva for both the positive diagnosis of Cushing syndrome and the differential diagnosis of pseudo-Cushing syndrome.

Materials and Methods: Patients having performed a complete cortisol diurnal cycle in both serum and saliva during their hospitalization in Cochin Hospital Endocrinology department from 2012 to 2018 were included. Their clinical and biological characteristics were collected from Cochin electronic medical record. Pseudo-Cushing syndrome was diagnosed in patients with repeated biological anomalies but whose follow-up allowed the elimination of hypercortisolism. Serum and saliva cortisol during diurnal cycle were determined in competition immunoassays.

Results: 466 patients were included in this study: 311 control subjects and 55 patients with pseudo-Cushing syndrome, grouped in “No-Cushing” (n=366); 73 patients with ACTH-dependent Cushing syndrome and 27 patients with cortisol-producing unilateral adrenal adenoma, grouped in “Cushing” (n=100). Salivary cortisol showed a good correlation with serum cortisol at all the times of the diurnal cycle (Spearman R ranging from 0.76 at 8 h to 0.88 at 20 h, P<0.0011). Considering the distinction between “Cushing” and “No-Cushing” groups; 24H-cortisol level was expectedly the most discriminant parameter. ROC analysis of 24H-cortisol showed equivalent diagnostic performances in both saliva and serum (AUC=0.95) giving a sensitivity of 89% and a specificity of 90% with a cut-off of 6.2 nmol/l and 175 nmol/l, respectively. Using these cut-offs, the proportion of false positive was>20% in the pseudo-Cushing group, highlighting the difficulty of this differential diagnosis. Interestingly, the ratio maximal/minimal cortisol level during the day in serum allowed a good discrimination between pseudo-Cushing and ACTH-dependent Cushing syndrome groups, a cut-off of 3 giving a sensitivity of 86% and a specificity of 91% (AUC = 0.93). This ratio in saliva was less performant (AUC = 0.82).

Discussion: Saliva cortisol correlates well with serum cortisol at all the times of diurnal cycle; 24H-saliva cortisol performing as well as 24H-serum cortisol for the positive diagnostic of Cushing syndrome. A ratio of maximal/minimal cortisol level in serum>3 is highly predictive of pseudo-Cushing versus ACTH-dependent Cushing syndrome diagnosis.

Volume 90

25th European Congress of Endocrinology

Istanbul, Turkey
13 May 2023 - 16 May 2023

European Society of Endocrinology 

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