Cortisol and cortisone analysis in serum and plasma by atmospheric pressure photoionization tandem mass spectrometry.
OBJECTIVE
Cortisol metabolism is controlled by 11beta-hydroxysteroid dehydrogenase (11beta-HSD) isoenzymes, which interconvert cortisol and cortisone. Accurate measurement of the cortisol and cortisone concentrations and their ratio provide useful information about 11beta-HSD activity.


METHODS
Cortisol and cortisone were extracted with methyl-tert-butyl ether from 100 microl of serum or plasma. The extract was evaporated, reconstituted with mobile phase, and analyzed by tandem mass spectrometry using a photoionization interface. The transitions monitored were: m/z 363 to 121 and 363 to 97 for cortisol, 361 to 163 and 361 to 105 for cortisone.


RESULTS
Within-run and between-run coefficients of variation were less than 6% and 12%; 14% and 22%; 11% and 21% for cortisol, cortisone, and their ratio, respectively. The limit of detection was 1 microg/l for cortisol and 5 microg/l for cortisone. Normal ranges for cortisol and cortisone concentration and for their ratio in plasma (n = 120) determined as the central 95% were 33-246 microg/l for cortisol, 8-27 microg/l for cortisone, and 0.081-0.301 for the cortisone/cortisol ratio.


CONCLUSIONS
We developed a simple sensitive method for cortisol and cortisone analysis in plasma and serum that uses a small sample volume. The method is very specific, fast, does not have any known interference, and is useful for diagnosis of variety of disease and pathologic conditions.
Kushnir
Mark M
MM
ARUP Institute for Clinical and Experimental Pathology, Salt Lake City, UT 84108, USA. kushnmm@aruplab.com
Neilson
Rebecca
R
Roberts
William L
WL
Rockwood
Alan L
AL
D042842:11-beta-Hydroxysteroid Dehydrogenases / Q000378:metabolism; D000328:Adult; D002851:Chromatography, High Pressure Liquid; D003348:Cortisone / Q000097:blood* / Q000378:metabolism; D006801:Humans; D006854:Hydrocortisone / Q000097:blood* / Q000378:metabolism; D007527:Isoenzymes / Q000378:metabolism; D013058:Mass Spectrometry / Q000295:instrumentation / Q000379:methods; D012016:Reference Values; D015203:Reproducibility of Results
D007527:Isoenzymes; D042842:11-beta-Hydroxysteroid Dehydrogenases; D003348:Cortisone; D006854:Hydrocortisone