Significantly high level of late-night free cortisol to creatinine ratio in urine specimen in patients with subclinical Cushing’s syndrome

サブクリニカルクッシング症候群における有意な夜間尿中遊離コルチゾールの排泄増加

Shiwa Tsuguka

Objective: Absence of a late-night cortisol nadir is a consistent biochemical abnormality in patients with cortisol-producing adenoma. We evaluated the abnormality of late-night urinary free cortisol to creatinine ratio (late-night UFCCR) in patients with subclinical Cushing's syndrome (SCS). Methods: Fifty-eight patients with incidentally detected adrenocortical adenomas [SCS: 9; nonfunctioning adenoma (NF): 49] were enrolled as subjects. Values measured in all patients were urinary free cortisol accumulated between 9:00 p.m. and 11:00 p.m. (late-night UFCCR), serum cortisol at 11:00 p.m. (midnight serum cortisol: MSC), serum cortisol after 1-mg overnight dexamethasone suppression test (1 mg-DST) and 24-h urinary free cortisol (UFC). Results: Median late-night UFCCR value in SCS was significantly higher than that in NF (P < 0.001). Significant correlations were observed between late-night UFCCR and each of serum cortisol after 1 mg-DST and MSC (r = 0.537, P < 0.001 and r = 0.556, P < 0.001, respectively). There was no significant correlation between serum cortisol after 1 mg-DST and 24-h UFC (r = 0.211, P = 0.112). In receiver operating characteristic analysis for diagnosis of SCS, the areas under the curves of latenight UFCCR and 24-h UFC were 0.937 (95% confidence interval 0.865-1.008) and 0.726 (0.874-0.999), respectively. Late-night UFCCR cut-off value of 4.9 nmol/μmol Cre showed a sensitivity of 100% and a specificity of 76.6%. Conclusion: Patients with SCS showed higher late-night UFCCR values than those with NF. Late-night UFCCR was significantly correlated with autonomous cortisol production findings. Diagnostic performance of late-night UFCCR was superior to 24-h UFC. These results suggest that late-night UFCCR might represent one of the simple and reliable tests for SCS diagnosis.

Medical sciences [ 490 ]

eng

Tsuguka Shiwa, Kenji Oki, Kiminori Yamane, Masayasu Yoneda, Tomokazu Awaya, Shuhei Nakanishi and Nobuoki Kohno; Significantly high level of late-night free cortisol to creatinine ratio in urine specimen in patients with subclinical Cushing's syndrome; Clinical Endocrinology, Volume 79, Issue 5, pages 617-622, November 2013 (doi: 10.1111/cen.12197) references

[DOI] http://doi.org/10.1111/cen.12197 references

広島大学