Interference in immunoassay measurements of total and free phenytoin in uremic patients: A reappraisal

W. L. Roberts; P. M. Rainey

doi:10.1093/clinchem/39.9.1872

Interference in immunoassay measurements of total and free phenytoin in uremic patients: A reappraisal

W. L. Roberts, P. M. Rainey

Research output: Contribution to journal › Article › peer-review

19 Scopus citations

Abstract

Accumulation of phenytoin metabolites in uremia has been shown to interfere with some immunoassay methods for phenytoin measurement. We evaluated the effects of uremia (serum creatinine > 13 mg/L) on free and total phenytoin concentrations measured by the Abbott TDx® fluorescence polarization immunoassay, and the DuPont aca® and Syva EMIT® homogeneous enzyme-multiplied immunoassay methods, using HPLC as the comparison method. In uremic patients, the TDx assay showed both fixed and proportional bias in comparison with the HPLC for both total phenytoin concentration (TDx = 1.24 x HPLC + 1.9 mg/L) and free phenytoin concentration (TDx = 1.52 x HPLC + 0.24 mg/L). The total bias was as great as 100% for both total and free phenytoin. Cross-reactive substances other than 5-(p-hydroxyphenyl)-5-phenylhydantoin (HPPH) and HPPH-glucuronide appeared to be responsible. In contrast, there was minimal interference with aca and EMIT assays.

Original language	English (US)
Pages (from-to)	1872-1877
Number of pages	6
Journal	Clinical Chemistry
Volume	39
Issue number	9
DOIs	https://doi.org/10.1093/clinchem/39.9.1872
State	Published - Jan 1 1993
Externally published	Yes

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Generated from Scopus record by KAUST IRTS on 2023-09-20

ASJC Scopus subject areas

Clinical Biochemistry
Biochemistry, medical

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title = "Interference in immunoassay measurements of total and free phenytoin in uremic patients: A reappraisal",

abstract = "Accumulation of phenytoin metabolites in uremia has been shown to interfere with some immunoassay methods for phenytoin measurement. We evaluated the effects of uremia (serum creatinine > 13 mg/L) on free and total phenytoin concentrations measured by the Abbott TDx{\textregistered} fluorescence polarization immunoassay, and the DuPont aca{\textregistered} and Syva EMIT{\textregistered} homogeneous enzyme-multiplied immunoassay methods, using HPLC as the comparison method. In uremic patients, the TDx assay showed both fixed and proportional bias in comparison with the HPLC for both total phenytoin concentration (TDx = 1.24 x HPLC + 1.9 mg/L) and free phenytoin concentration (TDx = 1.52 x HPLC + 0.24 mg/L). The total bias was as great as 100% for both total and free phenytoin. Cross-reactive substances other than 5-(p-hydroxyphenyl)-5-phenylhydantoin (HPPH) and HPPH-glucuronide appeared to be responsible. In contrast, there was minimal interference with aca and EMIT assays.",

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N2 - Accumulation of phenytoin metabolites in uremia has been shown to interfere with some immunoassay methods for phenytoin measurement. We evaluated the effects of uremia (serum creatinine > 13 mg/L) on free and total phenytoin concentrations measured by the Abbott TDx® fluorescence polarization immunoassay, and the DuPont aca® and Syva EMIT® homogeneous enzyme-multiplied immunoassay methods, using HPLC as the comparison method. In uremic patients, the TDx assay showed both fixed and proportional bias in comparison with the HPLC for both total phenytoin concentration (TDx = 1.24 x HPLC + 1.9 mg/L) and free phenytoin concentration (TDx = 1.52 x HPLC + 0.24 mg/L). The total bias was as great as 100% for both total and free phenytoin. Cross-reactive substances other than 5-(p-hydroxyphenyl)-5-phenylhydantoin (HPPH) and HPPH-glucuronide appeared to be responsible. In contrast, there was minimal interference with aca and EMIT assays.

AB - Accumulation of phenytoin metabolites in uremia has been shown to interfere with some immunoassay methods for phenytoin measurement. We evaluated the effects of uremia (serum creatinine > 13 mg/L) on free and total phenytoin concentrations measured by the Abbott TDx® fluorescence polarization immunoassay, and the DuPont aca® and Syva EMIT® homogeneous enzyme-multiplied immunoassay methods, using HPLC as the comparison method. In uremic patients, the TDx assay showed both fixed and proportional bias in comparison with the HPLC for both total phenytoin concentration (TDx = 1.24 x HPLC + 1.9 mg/L) and free phenytoin concentration (TDx = 1.52 x HPLC + 0.24 mg/L). The total bias was as great as 100% for both total and free phenytoin. Cross-reactive substances other than 5-(p-hydroxyphenyl)-5-phenylhydantoin (HPPH) and HPPH-glucuronide appeared to be responsible. In contrast, there was minimal interference with aca and EMIT assays.

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JO - Clinical Chemistry

JF - Clinical Chemistry

IS - 9

ER -

Interference in immunoassay measurements of total and free phenytoin in uremic patients: A reappraisal

Abstract

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