|Year : 2002 | Volume
| Issue : 17 | Page : 47--52
Excretion of Cortisol under Nocturnal Noise and Differences due to Analytic Techniques
Robert Koch-Institute, Federal Institute for Infectious and Noninfectious Diseases, Section: Environmental related disorders, Berlin, Germany
The measurement of urinary free cortisol is an established index for the diagnosis of disorders involving glucocorticoids (see Braun et al. 1999) but the amount of free cortisol in urine samples is dependent on the analytic-technology. Competitive binding assays and radioimmuno assays, the methods used most commonly in routine laboratories, missestimate the amount of free cortisol because of interference by strongly cross-reacting substances in urine (Schoneshofer et al. 1986b). The specificity of these tests is too low to distinguish between free cortisol and near metabolites. The revision of the long-term study by "online" liquid chromatography (HPLC) suggestes that immuno assay technique produce doubtful results, particulary when free cortisol and metabolites react in different ways. This is of particular importance, since several studies containing indications, that an acute demand leads particularly to alterations of free Cortisol and a chronic demand essentially to alterations of metabolites. Schoneshofer pointed out already in 1986 that by additional measuring of the 20α-Dihydrocortisol and Cortisone it may be possible to differentiate chronic hypercorticoidism from the acute state. In connection with the findings of the present comparison it is urgently required to standardize both the data collection and the data analysis to get comparable results. Therefore, it has to be concluded from today's point of view, that free cortisol and metabolites must be investigated with HPLC if urine samples are used.
Müller-BBM GmbH, Robert-Koch-Str. 11, 82152 Planegg bei München
Source of Support: None, Conflict of Interest: None
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