Say someone takes a test and it's negative, but only because it's very early on and the test only picks up 25 measurements on the hormone, and at the time you only have say 15. how much of the hormone does it take to cause common early symptoms, like nausea, itchy breasts, frequent urination, mood swings, constipation, etc.

In other words, can you have not enough HcG to activate a positve result on a test, but enough of the hormone to trigger some early symptoms?

yes you can. with my daughter, i had sore boobs, darker areola, and increased need to pee, for about 2 weeks before i got a positive on a first response test.

No- the HCG hormone is what gives the positive result on a pregnancy test. normally if you were to get a blood test at about 5 weeks your HCG level would be about 500 or so, and that is with only one child.