Ireland, well done you! Doctors continue to confirm the legitimacy of nighttime cortisol saliva samples in diagnosing Cushies. By now, this should totally be a given, but I am always please to see it repeated. Also, I find it interesting that the Irish use early morning cortisol-to-creatinine urine samples to diagnose. Hmm. Don't think I've heard of that being used in the USA. Nice to see the give the patient the opportunity to show high cortisol results in 28 days, not a few point-in-time tests that don't "catch" the high cortisol.
A comparison of the use of urinary cortisol to creatinine ratios and nocturnal salivary cortisol in the evaluation of cyclicity in patients with Cushing's syndrome.
J Clin Endocrinol Metab. 2013 Jan; 98(1):E72-6. doi: 10.1210/jc.2012-2925. Epub 2012 Nov 12.
Graham UM, Hunter SJ, McDonnell M, Mullan KR, Atkinson AB.
Regional Centre for Endocrinology and Diabetes, Royal Victoria Hospital, Grosvenor Road, Belfast BT12 6BA, United Kingdom. firstname.lastname@example.org
Cyclical Cushing's syndrome is detected in our center by collecting sequential early morning urine (EMU) samples for cortisol to creatinine ratio over 28 d. The Endocrine Society suggests that nocturnal salivary cortisol (NSC) may be used to assess patients for cyclical Cushing's. However, there is only very limited evidence that it correlates with early morning urine testing or that it demonstrates cycling over 28 d.
We sought to correlate nocturnal salivary cortisol with early morning urine results collected the following morning and to determine whether nocturnal salivary cortisol could be used to detect cyclical Cushing's.
DESIGN AND SETTING:
An observation study of 28-d collections for nocturnal salivary cortisol and early morning urine was performed in a tertiary referral center over 1 yr. Patients: A 28-d collection of nocturnal salivary cortisol and early morning urine was performed in 10 patients with confirmed or suspected Cushing's syndrome.
MAIN OUTCOME MEASURE:
The main outcome of the study was the correlation of salivary and urinary cortisol with graphical assessment of results for cycling.
Eleven collections were performed. One patient with cyclical Cushing's completed the collection before and after cabergoline therapy. Two hundred seventy matched salivary and urinary results were correlated (r = 0.79; P < 0.001). In two patients with cyclical Cushing's, early morning urine and nocturnal salivary cortisol followed a similar cyclical pattern. In one patient with recurrent cyclical Cushing's, cortisol was elevated in both saliva and urine but with more prominent cycles in saliva.
Nocturnal salivary cortisol correlated well with early morning urine. Nocturnal salivary cortisol detected all cases of cyclical Cushing's. Therefore, nocturnal salivary cortisol may prove to be an additional option or replacement for early morning urine in detecting cyclical Cushing's syndrome. [blogger emphasis]
PMID: 23150688 [PubMed - indexed for MEDLINE]
NOTE: Blogger changed all abbreviations for EMU and NSC to early morning urine and nocturnal salivary cortisol. This Cushie brain can’t remember what these mean half way down the article.