Characterization of cyclic Cushing's disease using late night salivary cortisol testing.

OBJECTIVE: To characterize a cohort of patients with cyclic Cushing's disease (CD) in comparison with noncyclic CD using late night salivary cortisol (LNSC) and examine the diagnostic sensitivity of LNSC in comparison with that of 24-hour urine-free cortisol (UFC) in this population.

DESIGN: Retrospective study of patients with CD seen in our institution between 2008 and 2017.

PATIENTS: A total of 205 patients, including 17 (8%) with cyclic CD (based on a minimum of 3 peaks and 2 troughs in cortisol levels). In a secondary analysis, 38 patients (19%) with cyclic CD were identified (based on a criterion of at least 2 peaks and 1 trough).

MEASUREMENTS: Data on presentation, laboratory tests and outcomes were extracted. The diagnostic sensitivity of LNSC vs UFC in establishing cyclic CD was calculated. Kaplan-Meier analyses of recurrence after transsphenoidal pituitary surgery (TSS) were performed.

RESULTS: The interval between presentation and TSS was significantly longer in patients with cyclic CD (P < .0001) in comparison with those with noncyclic CD. The sensitivity of LNSC in establishing cyclic CD was 88% and was higher than that of UFC (12%, P = .007). There were no differences in remission and recurrence rates between patients with cyclic CD and those with noncyclic CD.

CONCLUSIONS: Patients with cyclic CD account only for a minority of those with CD, but may require a lengthier diagnostic evaluation. The use of LNSC on multiple occasions provides a more sensitive method of detecting cyclic CD than UFC. Outcomes of TSS in cyclic CD are comparable to those with noncyclic disease.