The free cortisol calculated: correlation with the free cortisol concentrations measured with liquid chromatography-tandem mass spectrometry after equilibrium dialysis and establishment of reference intervals.
Fleur Wolff, Ken Geivaerts, Elise Mathieu, Cécile Duterme, Guillaume Deprez, David Fage, Frédéric Cotton
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引用次数: 0
Abstract
Background: Changes in cortisol binding globulin (CBG) impact the total serum cortisol concentration and affect the accurate assessment of adrenal function. Free biologically cortisol can be calculated using different equations or directly measured after complicated procedures.
Methods: The free cortisol index (FCI) obtained using the Bonte formula as well as the free cortisol concentration calculated (Coolens equation) were first estimated for 45 healthy workers. The CBG level was determined by a competitive radioimmunoassay and the total cortisol concentration, was measured with an electrochemiluminescent assay. The correlations between FCI, the free cortisol concentrations calculated and the free cortisol levels measured with liquid chromatography-tandem mass spectrometry after equilibrium dialysis were studied for those 45 samples. Reference limits were established on 158 healthy hospital workers and patients with serum samples collected between 7:30 am and 10 am.
Results: The FCI as well as the free cortisol concentrations calculated obtained for the 45 samples correlated significantly with the free cortisol levels measured. Although the cortisol and CBG levels were statistically higher in women using contraceptives compared with women not taking them as well as men, the calculated FCI and free cortisol concentrations did not differ between these groups. The medians (P2.5-P97.5) obtained for the 158 healthy workers were respectively 26.4% (12.3-51.6%) and 10.6 nmol/L (4.3-26.7 nmol/L).
Conclusions: This study highlighted a significant correlation between the FCI, the free cortisol concentrations calculated and the free cortisol levels measured with LC-MS/MS, it has also allowed the establishment of reference intervals for calculated FCI and free cortisol.
期刊介绍:
The Scandinavian Journal of Clinical and Laboratory Investigation is an international scientific journal covering clinically oriented biochemical and physiological research. Since the launch of the journal in 1949, it has been a forum for international laboratory medicine, closely related to, and edited by, The Scandinavian Society for Clinical Chemistry.
The journal contains peer-reviewed articles, editorials, invited reviews, and short technical notes, as well as several supplements each year. Supplements consist of monographs, and symposium and congress reports covering subjects within clinical chemistry and clinical physiology.