I saw the GP the other day to discuss my short (7 day) luteal phase, and she said the first thing to do was a progesterone test to check that I'm ovulating ok. (Sounds fair enough, though I'm pretty sure that I am ovulating. Anyway.) She told me to book the blood test for CD21. At the time I assumed she'd based this on my ovulation day, which, as I told her, tends to be day 19 or 20. However, after looking on MN, it seems that a 'Day 21' test is a fairly standard thing - presumably based on a 14 day cycle? Does this mean I should be booking my test for later than CD21?? Will my progesterone level be high enough only a day or two after O? (Can't book it for 7 days post-O because that's when my AF starts .) Can anyone help me out?
Day 21 is a standard test. It wouldn't make much difference to the overall result if it was done a day or two later.
BTW they like to see a level of 30 or over for this test. Day 21 is only part of the story though; they should also be testing your Day 2 LH and FSH levels. LH and FSH are important hormones as they kickstart the ovulation process.