Detection of Early Pregnancy Forms of Human Chorionic Gonadotropin by Home Pregnancy Test Devices

In conclusion, we confirm that H-hCG is the principal source of hCG immunoreactivity in early pregnancy urines and show that only 6 of 15 home pregnancy test devices analytically detect this important molecule as effectively as they detect regular hCG. We also show wide variance in the limit of devices for detecting regular hCG and H-hCG. The data indicate that if home pregnancy test devices were reformulated to better recognize H-hCG, they could detect pregnancy even earlier than possible at present.

We query the meaning of the >99% accuracy advertised by manufacturers. Considering our H-hCG findings, together with the analytical detection limits of home pregnancy tests and the wide variability in hCG concentrations, we question the claims of home pregnancy tests. Confusing claims, such as the >99% accuracy, apparently derive from FDA guidelines. We suggest that these guidelines need to be examined.

FDA regulations should include detection limits for regular hCG and H-hCG. Regulations should also incorporate measurement of clinical sensitivity for detecting pregnancy on the first day of the missed menstrual period and other set time points. Defined measures of diagnostic accuracy (e.g., clinical sensitivity and specificity) should be reported on manufacturer’s packaging and inserts rather than "over 99% accuracy".

Full article: http://www.clinchem.org/cgi/content/full/47/12/2131#T1

Table 1. Evaluation of 15 home pregnancy tests with regular hCG and H-hCG standards.1

http://www.clinchem.org/cgi/content/full/47/12/2131/T1