Specificity assessment of immunoassay kits for determination of urinary free cortisol concentrations
| Autor: | Takeshi Kidowaki, Norihiko Aoki, Tatsuji Endo, Keiko Homma, Hitoshi Horie, Yuhei Koyama, Akira Kambegawa |
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| Rok vydání: | 2007 |
| Předmět: |
Adult
Male Hydrocortisone Clinical Biochemistry Radioimmunoassay Urine Cross Reactions Biochemistry High-performance liquid chromatography Gas Chromatography-Mass Spectrometry Urinary free cortisol medicine Humans Pituitary ACTH Hypersecretion Chromatography High Pressure Liquid Chromatography medicine.diagnostic_test Chemistry Elution Biochemistry (medical) Cross reactions General Medicine Immunoassay Reagent Kits Diagnostic Gas chromatography–mass spectrometry Glucuronide |
| Zdroj: | Clinica Chimica Acta. 378:66-70 |
| ISSN: | 0009-8981 |
| Popis: | Background In immunoassay kits for determination of urinary free cortisol (UFC) concentrations, the results vary markedly from kit to kit, so we compared in this study the reaction specificity among 4 commercially available immunoassay kits to determine the applicability of these assays in routine determination of UFC concentrations. Method Using 4 commercially available kits, cross-reaction was investigated. In addition, urine samples were fractionated by HPLC to investigate endogenous immunoreactive cortisol responses. HPLC fractions were subjected to gas chromatography-mass spectrometry (GCMS) to identify substances causing inter-kit assay discrepancies. Results Among the 4 kits, cortisol Kit “TFB” (Immunotech; IOT-RIA method) showed the lowest cross-reaction (2.5%) for prednisolone. Furthermore, on HPLC, 87.8% of the reaction of the entire fraction was seen in the fractions corresponding to the elution position of standard cortisol with the IOT-RIA method; this was the highest percentage among the 4 kits. GCMS revealed that the substance that showed a cross-reaction with the other 3 kits was 5α-tetrahydrocortisol (5α-THF) glucuronide. Conclusions The IOT-RIA method was found to be the most specific for UFC. The other 3 commercially available kits showed cross-reaction with a conjugate of 5α-THF, found to be one of the causes of inter-kit assay discrepancies. |
| Databáze: | OpenAIRE |
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