Variability of Late-Night Salivary Cortisol in Cushing Disease: A Prospective Study

Background The frequency of variable hormonogenesis in patients with Cushing disease (CD) but without cyclical symptoms is unclear. Aim To assess the frequency of variable hormonogenesis in patients presenting with CD. Methods Over a 6-month period, patients with confirmed or suspected CD provided late-night salivary samples for up to 42 consecutive nights. Results Of 19 patients confirmed to have CD, 16 provided at least 7 consecutive salivary samples, and 13 provided at least 21; these 16 patients are the subjects of this report. Twelve patients had at least three peak and two trough levels of late-night salivary cortisol (LNSC) but in only two patients were strict criteria for cyclical hormonogenesis fulfilled; variation was assessed as random in the others. Eight patients had de novo CD, and eight had recurrent/persistent disease. All patients with recurrent/persistent CD had two or more normal results, and in four of these patients, >50% of LNSC were normal. In six patients with de novo disease with at least one normal LNSC level, the maximum levels ranged from 1.55 to 15.5 times the upper limit of normal. Conclusions Extreme fluctuations of cortisol production, measured by sequential LNSC, are common in CD. In newly diagnosed disease, this may only occasionally impair diagnostic ability, whereas in most patients with recurrent/persistent disease after pituitary surgery, LNSC is frequently within the reference range, with potential to cause diagnostic problems.