Screening for Interference in Immunoassays

Screening for interference in immunoassays.

Screening for interference in immunoassays.

BACKGROUND The presence of interfering substances in patient samples submitted for immunoassay cannot be reliably anticipated. We therefore evaluated three interference screening techniques and estimated the prevalence of interfering substances as defined by positive outcomes with these protocols. METHODS We evaluated 160 samples for the presence of substances that may interfere with four imm...

Efavirenz interference in urine screening immunoassays for tetrahydrocannabinol.

BACKGROUND It has been known for some time that the antiretroviral drug, efavirenz (EFV), cross-reacts in urine immunoassays for tetrahydrocannabinol (THC). Because published studies investigating this phenomenon are limited, cross-reactivity information for several immunoassays is lacking. Reports of possible false-positive THC results from clinicians conducting workplace testing prompted us t...

Interference in immunoassays: avoiding erroneous results

types of immunoassay interference are similar to interferences in other chemistry assays and some types are unique to immunoassays. The interfering substance (interferent) in the sample may be exogenous to the patient, for example a drug, or endogenous, for example antibodies produced by the patient. The bias caused by interference may be positive or negative and, in some cases, the degree and ...

Metabolite and matrix interference in phenytoin immunoassays.

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 a...