hook effect


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hook effect

falsely low values on an immunoassay when an overwhelming amount of antigen affects the binding capacity of the added antibody; especially when testing for thyroglobulin in management of thyroid cancer.

hook effect

A curvilinear artefact occasionally seen in the immunoradiometric assay (IRMA) which appears when the hormone being measured is present in very high concentrations. The detector system will not measure the excess, as it will have reached a theoretical limit; the decreased counts bound with the labelled antibody at high hormone levels result in a spuriously decreased result being reported. IRMA should not be used for measuring hormones that may be in high concentrations—hCG, prolactin, or gastrin in clinical samples. The hook effect requires the measurement of two different concentrations to establish linearity.
References in periodicals archive ?
04 [micro]g/g and does not exhibit a high-dose hook effect up to 64,800 [micro]g/g.
Screening method to evaluate point-of-care human chorionic gonadotropin (hCG) devices for susceptibility to the hook effect by hCG E core fragment: evaluation of 11 devices.
The hook effect has long been recognized (4, 5), and current automated protein analyzers have been optimized to detect and mediate the hook effect (6-8).
After the base model was selected, we developed incrementally more complex models that then included a hook effect and interaction terms between hook and other factors.
The capacity of the equipment ensures there is no cross-reactivity with near neighbour strains or household powders; no set up time is required; it does not need expensive readers; decontamination is not necessary; there are no false positives or false negatives and there is no hook effect.
However, most manufacturers have developed devices that can bind very high hCG concentrations, and today the hook effect occurs primarily in the presence of pathologically increased hCG such as gestational trophoblastic disease [i.
9) The hook effect can cause very low hCG results or false-negative results when an extremely high hCG concentration is present due to the saturation of all antibody-binding sites on both the capture and signaling antibodies, permitting few or no complex formation.
The equipment detects the presence of these agents in as little as 3 minutes with no hook effect.
This is especially true for certain immunoassays susceptible to the hook effect, such as tumor markers that can vary in concentration over several orders of magnitude.
If a hook effect is present, the concentration of the diluted sample will be markedly greater than the undiluted sample.
Unfortunately, in the interim period, the initial lab had discontinued its initial platform, so there was no way to assay the high value on the initial platform to determine if the hook effect was the problem.