Cortisol fluorescence immunoassay

M12. Miyai, K., Watanabe, F., Kobayashi, Y., Tsubota, N., and Yahata, M., Fluorescence immunoassay of cortisol. Int. Congr. Clin. Chem., 11th 1251-1260(1982). 

Figure 19.64. Cortisol fluorescence poUiizSIioD immunoassay. Redrawn from Ref. 176.

Altliough methods involving organic solvent extraction or protein precipitation wfil estimate both free and protein-bound cortisol in tlie circulation, immunoassay-based methods that determine cortisol directly from serum have essentially replaced all extraction-based methods for routine cortisol measurements save for urine free cortisol methods. Flistorically four general methods have been used for the quantitative estimation of total blood cortisol concentrations in the clinical laboratory. These are the Porter-Silber color reaction method modified for plasma,the use of sulfuric acid-induced fluorescence, HPLC methods, or immunoassay. In general, HPLC and immunoassay are now used in both clinical laboratories and reference laboratories for the quantitative determination of cortisol in serum or urine. 

Lentjes EG. Free cortisol in serum assayed by temper-ature-controEed ultrafiltration before fluorescence polarization immunoassay. Clin Chem 1993 39 2518-21. 

Martinus J, Klein L, Fino J, Shipchandler M, Wang P. A fluorescence polarization immunoassay (FPIA) for the quantitation of cortisol. Clin Chem 1985 31 956. 

Weller RA. Comparison of fluorescent polarization immunoassay and radioimmunoassay in measuring cortisol levels in prepubertal depressed children. Am J Psychiatry 1992 149 1395-6. 

A fluorescence-quenching immunoassay for cortisol, based upon the use of a tracer comprising fluorescein linked to the steroid via a 21-amino-group, claims a good correlation with radioimmunoassay results. Separation of free and bound fractions is unnecessary with this system.141... 

The condensation product of oestradiol 17-hydrogen succinate and ethylene-diamine has been linked to fluorescein isothiocyanate to provide a fluorescence-labelled oestradiol for study of oestradiol uptake by cell nuclei. Fluorescence polarization immunoassay of serum cortisol provides a sensitive method which does not depend upon separation of bound and free materials. ... 

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