Possible false-negative results on therapeutic drug monitoring of phenytoin using a particle enhanced turbidimetric inhibition immunoassay in a patient with a high level of IgM

Kenshiro Hirata, Junji Saruwatari, Yuhuki Enoki, Kazufumi Iwata, Yukino Urata, Keiji Aizawa, Kentaro Ueda, Takumi Shirouzono, Motoki Imamura, Hiroshi Moriuchi, Yu Ishima, Daisuke Kadowaki, Hiroshi Watanabe, Sumio Hirata, Toru Maruyama, Eiko Fukunaga

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

In this report, the authors described the unusual case of a patient in whom the plasma phenytoin concentration was unexpectedly not detected on a particle-enhanced turbidimetric inhibition immunoassay (PETINIA) technique, a typical immunoassay for phenytoin. The plasma concentration was measured using PETINIA and high-performance liquid chromatography in a 69-year-old male patient treated with fosphenytoin intravenously at the standard dose for 7 days. Although the plasma concentration of phenytoin was below the limit of detection (<0.5 mcg/mL) on PETINIA after the administration of fosphenytoin, the trough plasma concentration was estimated to be between 5 and 10 mg/L on high-performance liquid chromatography. When the plasma concentrations of IgM and IgG were measured using an enzyme-linked immunosorbent assay, the plasma IgG level was within the reference range, whereas the plasma IgM level was 2-3 times higher than the upper limit of the reference range. We concluded that the PETINIA method yielded a possible false-negative result regarding the phenytoin level in this patient, perhaps because of some hindrance to the measurement process by IgM. This case suggests that false-negative results should be considered when therapeutic drug monitoring reveals abnormally low values using PETINIA and that it is necessary to evaluate the plasma IgM level.

Original languageEnglish
Pages (from-to)553-555
Number of pages3
JournalTherapeutic Drug Monitoring
Volume36
Issue number5
DOIs
Publication statusPublished - 2014 Oct 12
Externally publishedYes

Keywords

  • IgM
  • false-negative
  • particle-enhanced turbidimetric inhibition immunoassay
  • phenytoin
  • therapeutic drug monitoring

ASJC Scopus subject areas

  • Pharmacology
  • Pharmacology (medical)

Fingerprint Dive into the research topics of 'Possible false-negative results on therapeutic drug monitoring of phenytoin using a particle enhanced turbidimetric inhibition immunoassay in a patient with a high level of IgM'. Together they form a unique fingerprint.

Cite this