Not really on HRT, Crispy. The NHS pays no attention to when bloods are done if you're on HRT and get levels checked. They are not trying to get you within range for that part of your cycle.
And yes, I do need my baseline level to be high enough to even out the fluctuations. If my own body is creating peaks of 1500pmol and then it is cutting out to 50pmol, at random moments during the month (not correlated with the cycle, as that is what peri chaos is), then that is going to cause huge symptoms. Whereas if my baseline from HRT is around 450-500pmol, that prevents the dip from being too low. And no, I don't need to know what my levels are at their peak because that is short-lived and temporary (just like it would be in a pre-menopausal woman not on HRT) plus as I progress through menopause it's going to change a lot as I will stop making that much E as my own cycles cease, so it's chasing a moving target to even be interested in it.
Pre-menopausally, E would not be in 300s during someone's period, no. But I'm not pre-menopausal, I'm treating the hormonal chaos of peri-menopause so I need a higher buffer to negate those fluctuations. The levels for each part of the cycle are irrelevant once you start HRT. OR even once you are peri, if you test at any other time of the month - since you don't know how much is coming from you and how much from HRT. The only way to make sense of that is to test during your period to try to eliminate most of what's coming from you... otherwise it's a pointless test altogether.
By the way, when my E was around 330pmol during my period, I did not bleed when I withdrew P each month. I did not have enough E to even cause any build up at all. Only now I've increased E am I having something more like a normal period, although it's much lighter. And only since increasing E above that level has my heart stopped pounding through the night, and my inner tremors died down to a faint buzzing in my feet, and my sleep improved considerably. So I can tell that my body needs higher E.
bomb - randox don't do venous blood draw kits that I can see. It's finger prick or go to their clinics....