Cushing’s syndrome vs simple obesity. How can a needle be found in the haystack?

Endocrinology Today 02/2015; 4(1):30-35.

Clinical recognition of Cushing’s syndrome should generally follow from the observation of a constellation of compatible clinical features that progress over time. Screening for Cushing’s syndrome in patients with individual features of the metabolic syndrome, such as obesity, hypertension and hyperglycaemia, is not recommended.

Early diagnosis reduces unnecessary suffering and the ultimate lifetime sequelae of Cushing’s syndrome. Confirmation involves the demonstration of biochemical hypercortisolism, and the extent of diagnostic testing needs to be based on the degree of clinical suspicion.
Read the whole article here, in PDF format

Salivary cortisol performs better than urinary free cortisol to diagnose Cushing’s syndrome

Late-night salivary cortisol has a better performance than urinary free cortisol in the diagnosis of Cushing’s syndrome.

Salimetrics highlights a recent study:  Abstract

Context: The comparison of variability, reproducibility, and diagnostic performance of late-night salivary cortisol (LNSF) and urinary free cortisol (UFC) using concurrent and consecutive samples in Cushing’s syndrome (CS) is lacking.

Objectives, Patients and Methods: In a prospective study, we evaluate three simultaneous and consecutive samples of LNSF by RIA and UFC by LC-MS/MS in Cushing’s disease (CD; n=43), adrenal CS patients (n=9) and obese subjects (n=18) in order to compare their diagnostic performances. In CS patients we also performed a modified Cushing’s syndrome severity index (CSI).

Results: There was no difference in the coefficient of variation (%) between LNSF and UFC among the three samples obtained for each patient with CD (35±26vs31±24), adrenal CS (28±14vs22±14) and obesity (39±37vs48±20). LNSF confirmed the diagnosis of hypercortisolism even in the presence of normal UFC in 17.3% of CS, whereas the inverse situation was not observed for UFC. The area under the ROC curves for LNSF was 0.999 (95%CI 0.990-1.00) and for UFC was 0.928 (95%CI 0.809- 0.987). The ratio between AUCs was 0.928 (95%CI 0.810-0.988) indicating better performance of LNSF than UFC in diagnosing CS. There was no association between the severity of CSI and the degree of biochemical hypercortisolism.

Conclusion: Our data show that despite similar variability between both methods, LNSF has a superior diagnostic performance than UFC and should be used as the primary biochemical diagnostic test for Cushing’s syndrome diagnosis.

Authors Elias P, Martinez E, Barone B, Mermejo L, Castro M, Moreira A
Division of Endocrinology-Department of Medicine and Division of Statistics- Department of Social Medicine, Ribeirao Preto Medical School – University of Sao Paulo, Ribeirao Preto, SP- Brazil
LINK to Paper
Salimetrics guide to Cortisol
LINK to Salimetrics Diagnostic Salivary Cortisol Assay

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