Free Cortisol Index As a Surrogate Marker for Serum Free Cortisol

Overview

Journal Ann Clin Biochem

Specialty Biochemistry

Date 2002 Jul 16

PMID 12117446

Citations 19

Authors

Carel W le Roux

Sivajenani Sivakumaran

Jamshid Alaghband-Zadeh

Waljit Dhillo

Wing May Kong

Michael J Wheeler

Affiliations

Soon will be listed here.

Abstract

Background: The biologically active component of a hormone is the unbound or free fraction. Changes in cortisol-binding protein could give misleading results if only total cortisol is measured for the interpretation of dynamic function tests.

Methods: This study aimed to measure serum free cortisol using a steady-state gel-filtration method and then to evaluate the correlation between the serum free cortisol and the free cortisol index (FCI), defined as serum total cortisol/cortisol-binding globulin (CBG).

Results: Forty-eight serum samples from healthy volunteers undergoing a short Synacthen test were analysed for total cortisol, free cortisol and CBG. The FCI correlated well with a previously established, but more complex, calculation of serum free cortisol (R = 0.98, P <0.001) and with measured serum free cortisol (R = 0.90, P < 0.001).

Conclusion: Free cortisol index is a reliable and user-friendly measure of serum free cortisol.

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