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Editorial |
Montreal General Hospital, 1650 Cedar, Room C6260, Montreal, Quebec H3G 1A4, Canada
When urinary free cortisol (UFC) determinations became readily available for clinical use in 1968 (1), chromatographic methods were cumbersome. The first competitive protein-binding method (radiotransinassay) (1) used human corticosteroid-binding globulin (transcortin) as the binding protein. The specificity of the assay was enhanced by the use of Fullers earth as the agent to adsorb the unbound fraction because it takes up some of the competing steroids differentially (2). The reference interval was ~10100 µg/day (30300 nmol/day).
When radioimmunoassays, based on the same competitive binding principle but using antibodies raised to cortisol linked to albumin, became popular during the 1970s, it was assumed that these would be more specific for cortisol, but this assumption was not warranted. As pointed out recently (3), most of the articles published over the past 20 years have quoted even higher values, reflecting a significant lack of specificity.
In 1976, Chattoraj et al. (4) found values for UFC after
combined thin-layer and column chromatography that were
approximately one-half those of the original method (
References
The following articles in journals at HighWire Press have cited this article:
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J A Jackson, M P Wailoo, J R Thompson, and S A Petersen Early physiological development of infants with intrauterine growth retardation Arch. Dis. Child. Fetal Neonatal Ed., January 1, 2004; 89(1): F46 - F50. [Abstract] [Full Text] [PDF] |
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R. S. Fink, L. N. Pierre, P. T. Daley-Yates, D. H. Richards, A. Gibson, and J. W. Honour Hypothalamic-Pituitary-Adrenal Axis Function after Inhaled Corticosteroids: Unreliability of Urinary Free Cortisol Estimation J. Clin. Endocrinol. Metab., October 1, 2002; 87(10): 4541 - 4546. [Abstract] [Full Text] [PDF] |
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R. L. Taylor, D. Machacek, and R. J. Singh Validation of a High-Throughput Liquid Chromatography-Tandem Mass Spectrometry Method for Urinary Cortisol and Cortisone Clin. Chem., September 1, 2002; 48(9): 1511 - 1519. [Abstract] [Full Text] [PDF] |
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B. J. Lipworth, R. A. Nathan, and R. ZuWallack Fluticasone and Cortisol Measurements Chest, March 1, 2001; 119(3): 984 - 985. [Full Text] [PDF] |
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