Late-night salivary cortisol often fluctuates widely in Cushing’s disease
Among patients with new, persistent or recurrent Cushing’s disease, researchers observed cortisol levels that fluctuated widely over 6 months, with measurements falling into the normal range more than 50% of the time for a few patients, according to findings from a prospective study.
“Cortisol levels, as represented by late-night salivary cortisol, in Cushing’s disease patients without variable symptoms fluctuate much more widely than many endocrinologists may realize,” Laurence Kennedy, MD, FRCP, chairman of the department of endocrinology, diabetes and metabolism at the Cleveland Clinic, told Endocrine Today. “In patients with recurrent or persistent Cushing’s disease, the late-night salivary cortisol can be normal much more frequently than has been appreciated.”
Kennedy and colleagues analyzed late-night salivary samples (between 11 p.m. and midnight) from 16 patients with confirmed Cushing’s disease for up to 42 consecutive nights between January and June 2014 (age range, 27-62 years). Researchers defined normal late-night salivary cortisol as between 29 ng/dL and 101 ng/dL.
Within the cohort, eight patients had a new diagnosis of Cushing’s disease and underwent transsphenoidal surgery; eight patients had recurrent or persistent Cushing’s disease.
Researchers observed at least three peaks and two troughs in 12 of the 16 patients, and late-night salivary cortisol levels were in the normal range on at least one occasion in 14 patients (all patients with recurrent/persistent disease and six of eight patients with new disease). Only two of the 16 patients exhibited fluctuations that were deemed cyclical, according to researchers, with the interval between peaks approximately 4 days, they noted.
In five of the eight patients with recurrent or persistent disease, the lowest late-night salivary cortisol measurement was at or below the limit of detection on the assay and approximately 1 in 3 measurements were in the normal range, researchers found. Four patients had normal measurements more than 50% of the time.
Additionally, six of the patients with recurrent or persistent disease had measurements in the normal range on two consecutive nights on at least one occasion, two patients had six such measurements in a row, and one had 31 consecutive normal levels, according to researchers.
In six patients with newly diagnosed Cushing’s disease with at least one normal late-night salivary cortisol measurement, the maximum levels ranged from 1.55 to 15.5 times the upper limit of normal.
“First, widely fluctuant cortisol levels in patients with Cushing disease do not appear to be associated with fluctuating symptoms, at least in our patient population,” Kennedy said. “Second, you need to be careful drawing conclusions on the efficacy of potential medical treatments for Cushing’s disease based on only one or two late-night salivary cortisol levels, given the extreme variation that occurs in the untreated patient. Third, diagnosing recurrent or persistent Cushing’s disease can be challenging at the best of times, and, though it is felt that late-night salivary cortisol may be the best test for early diagnosis, it may require more than the suggested two, three or four tests on successive nights to make the diagnosis.”
Kennedy said better tests for diagnosing Cushing’s disease are needed, adding that investigating the potential utility of salivary cortisone could be useful. – by Regina Schaffer
For more information:
Lawrence Kennedy, MD, can be reached at Cleveland Clinic, Department of Endocrinology, Diabetes and Metabolism, 9500 Euclid Ave., Cleveland, OH 44195; email: firstname.lastname@example.org.
Disclosures: The authors report no relevant financial disclosures.