How long can I save FMU?

[texasfarmom]

I tested with FMU on a Dollar Tree test and it came up + well within the time limit. But last month I got several + looking tests as well with $T and I wasn't pregnant. I want to go get a FRER, but it will be hours before I'm able to. How long after I collect my FMU can I use it to test with?

[Jaimee]

That is an excellent question!  I wonder if anyone here knows!  I'll try to find out some info... But, I will say that a lot of women have decent results by storing up their pee for 4+ hours before testing later in the day.  You could try that.  Or attempt to wait until tomorrow morning!

[Jaimee]

Ah, good old POAS.com to the rescue

Can I still use pee that's been sitting in a cup for several hours? hCG (pregnancy hormone) does break down and dissipate from urine once it leaves the body. It has a half-life of 24 hours, meaning the total amount will be cut in half for every day it sits out. If you are testing very early when only a small amount of hCG is present to begin with, that half might make a difference (for example, 25 mIU/mL of hCG will be detected with any early pregnancy test. By the time that pee sits out for a day, it has only 12.5 mIU/mL left, and only a very sensitive test may detect it.)

However, most women aren't peeing in cups and leaving it around for days; most women just want to save their FMU (or other concentrated urine) to be used later in the day (may need to purchase an HPT, want to wait for darling dearest to get home from work, may pee in a cup out of preference and then get distracted by a toddler doing a serious number on the poor kitty before you get the chance to dip the test, etc. All very common scenarios.) A few hours is unlikely to make a serious difference in the amount of hCG in your urine, so it's fine to use older pee. Putting your pee in the fridge will also slow the breakdown of the hormone, but I will disavow all knowledge of this suggestion in the event that your husband is grossed out by its proximity to his leftover pizza.

Several other sites seem to confirm a half life of 24-36 hours.  So, just keep in mind if your levels are right around the test sensitivity (25) and you leave the urine out for 24 hours, the hCG present could fall to 12ish and a BFN.  But if you're over the test sensitivity and test just 6 hours later then it is unlikely to be a problem.

[texasfarmom]

Thanks Jaime for sharing this!