Endocrine Abstracts

Background: Measurement of serum cortisol levels can be useful in the diagnosis of conditions of both adrenal insufficiency and excess. Several methods are available for the measurement of the cortisol levels and immunoassays are commonly used in routine laboratories. The aim of our study was therefore to compare four different automated immunoassays for measurement of cortisol in serum.

Methods: Serum samples of seventy two healthy volunteers were used for this comparison of methods. Levels of cortisol were measured with the Architect (Abbott diagnostics), Cobas e411 (Roche diagnostics) DxI (Beckman Coulter) and Liaison (DiaSorin) automated immunoassays.

Results: The four immunoassays were significantly correlated among each other (P<0.0001). The mean concentrations (range) were: 326 nM (185–811) for the Architect, 422 nM (200–1142) for the Cobas e411, 343 nM (176–777) for the DxI and 251 nM (113–458 nM) for the Liaison. The mean differences observed with the Bland and Altman plots were − 102 nM (Architect - Cobas e411), −16 nM (Architect - DxI), 91 nM (Architect - Liaison), 86 nM (Cobas e411 - DxI), 396 nM (Cobas e411 - Liaison) and 113 nM (DxI - Liaison).

Conclusions: Automated immunoassays for the measurement of cortisol levels are significantly correlated. However, the results are not commutable between the assays and more standardization is still required for cortisol measurement.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.