If you are a hardcore ttc-er you are without doubt familiar with the website http://www.peeonastick.com
It’s a veritable mine of useful information regarding all things pregnancy test related. with tables of test sensitivity by brand, explanations of why you can’t reuse a test, why digital tests all have 2 lines (if you break them open), why you shouldn’t break tests open, the dangers of allowing your OPK and HPT to touch and, of course, using an OPK as a HPT.
See it turns out that the only thing differentiating lutinising hormone and human chorionic gonadotrophin is a beta subunit (basically a secondary protein structure) found on the end of the hcg molecule. It’s this subunit that a HPT is specific for (and why a pregnancy blood test is referred to as a “beta” or “beta hcg” count). An OPK doesn’t differentiate between the two so it will detect either LH or HCG, so theoretically you can use it as a pregnancy test. It’s worth noting though that OPKs are not as sensitive as HPTs so you’d likely get a positive on a HPT before you would on an OPK AND there is no way to know which hormone it is being detected.
Bearing all that in mind….
I may have pee’d on some OPKs. Technically that’s not breaking my promise not to take a pregnancy test before Sunday. Ooooo I wonder what this means?