Screening method to evaluate point-of-care human chorionic gonadotropin (hCG) devices for susceptibility to the hook effect by hCG β core fragment: evaluation of 11 devices.
BACKGROUND
The predominant hCG variant in urine, hCG β core fragment (hCGβcf), has been demonstrated to cause false-negative results in qualitative point-of-care (POC) hCG devices. This is a major concern for healthcare professionals using POC pregnancy tests. We developed a screening method to evaluate qualitative POC hCG devices for their susceptibility to inhibition by hCGβcf. Using this method, we evaluated the performance of 11 commonly used devices.


METHODS
A wide range of purified hCG and hCGβcf concentrations were mixed and tested on 2 POC devices. By use of those results, a screening method was defined and 9 additional POC devices were evaluated. Two solutions containing (a) 500 pmol/L (171 IU/L) intact hCG with 0 pmol/L hCGβcf and (b) 500 pmol/L intact hCG with 500 000 pmol/L hCGβcf were used to screen all POC devices.


RESULTS
The OSOM and Cen-Med Elite devices were found to be most susceptible to false-negative results due to hCGβcf. The BC Icon 20 and the Alere were the least susceptible. The remaining 7 were moderately affected. Devices that gave the strongest signal with hCGβcf alone were those that were least likely to show a hook effect.


CONCLUSIONS
The screening method put forth here can be used by device users and manufacturers to evaluate POC devices for inhibition by hCGβcf. Of 11 devices evaluated, only 2 have been identified that exhibit minimal to no susceptibility to hCGβcf.
Department of Pathology and Immunology.
Robert D
RD
Nerenz
Haowei
H
Song
Ann M
AM
Gronowski
D006063:Chorionic Gonadotropin / Q000652:urine*; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000652:urine; D005188:False Negative Reactions; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000295:instrumentation; D019095:Point-of-Care Systems; D011247:Pregnancy; D011258:Pregnancy Tests / Q000295:instrumentation*
D006063:Chorionic Gonadotropin; D018997:Chorionic Gonadotropin, beta Subunit, Human