Qualitative point-of-care and over-the-counter urine hCG devices differentially detect the hCG variants of early pregnancy

Abstract

Background Qualitative point-of-care (POC) tests for human chorionic gonadotropin (hCG) vary in their ability to detect purified hCG variants and there is data to suggest that over-the-counter (OTC) devices might also display similar variability. This could potentially influence the detection of urine hCG in early pregnancy. Methods Six OTC devices were tested for their ability to detect 5 hCG variants. Ten early pregnancy urine specimens were selected for their diverse expression of hCG variants. The samples were tested with 6 brands of POC and 6 OTC devices. Results OTC devices consistently recognized intact hCG, hCGn, and hCGβ. hCGβn was consistently recognized by 4 out of 6 brands. One brand inconsistently recognized hCGβcf. OTC and POC devices varied greatly in their ability to detect hCG in early pregnancy urine, despite the fact that urine samples were adjusted to the same intact hCG concentration. Interestingly, we found that the OTC devices had better analytical sensitivity than the POC devices. Clinitest ® and First Response ® demonstrated the lowest hCG detection limits for POC and OTC devices, respectively. Conclusions Both OTC and POC devices are capable of detecting hCG concentrations in early pregnancy urine, and OTC devices demonstrated better analytical sensitivity relative to POC devices.