Metabolite and matrix interference in phenytoin immunoassays

Petrie M. Rainey, Katherine E. Rogers, William L. Roberts

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


The major phenytoin metabolite, 5-(p-hydroxyphenyl)-5-phenylhydantoin glucuronide (HPPG), was primarily responsible for the positive bias noted when uremic specimens were assayed with the Abbott TDx® Free Phenytoin fluorescence polarization immunoassay. The amount of bias depended on both HPPG and phenytoin concentration, increasing with increases in either concentration. The new Abbott TDx II assays for phenytoin and free phenytoin exhibited no significant cross-reactivity with HPPG and no bias in clinical specimens from uremic patients. Both assays correlated well with Emit-based assays (r >0.98), had CVs of
Original languageEnglish (US)
Pages (from-to)1645-1653
Number of pages9
JournalClinical Chemistry
Issue number10
StatePublished - Jan 1 1996
Externally publishedYes

ASJC Scopus subject areas

  • Clinical Biochemistry
  • Biochemistry, medical


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