A widely held belief states that when using a home UA test, the intensity of the red/pink line in the test window can indicate how close someone is to the 50 ng/ml threshold, commonly used as the cutoff levels for UA tests.
Using myself as an example, I have abstained for 2 months now, due to an upcoming UA in a week or two. I purchased about 15 drug tests off the internet, and I have tested myself for the last month or so. I have found that as soon as yesterday, when I used my first void of the day, I have had results on the UA where the test line is just as faint as the test line was a month ago, when using the first void of the day as well.
I have always heard that thc has a half-life anywhere from 1-10 days. Therefore, if I passed multiple tests one month ago, that would mean I passed with a max thc byproduct count of 49.99 ng/ml. Because the half-life is a max of 10 days, that means that 10 days later my max ng/ml count would be at 24.98, and another ten days later (which was a few days ago) the max count would be 12.99. However, the tests I have taken recently have had test lines which were just as faint as the test lines a month ago (yes, I took pictures). This has been the case, even though by definition, the ng/ml in my body surely decreased during this time due to thc half-life.
I understand one possible explanation would be exercise and diet, however, these two things have been completely consistent with me for months and months now. I eat the same exact stuff, and run 4 times a week, for many months now. I run on the same days of the week every week, and I took the tests on the same days of the week every week!!
Therefore, it is my feeling that when people say a fainter line means you are closer to the "threshold" this is actually inaccurate. I know a lot of knowledgeable people post here, so I am curious if anyone has any reasons why my thinking is incorrect.