I have an estrogen implant and it has been quite efficient. When I saw the endo a while ago at the six month mark of it being implanted he was very happy with my E levels saying they were over 100 and something, and that I wouldn't need to replace implant until the levels dropped under 80 whatevers. So now, almost three months later, I wonder if it has dropped, I have been feeling somewhat down and irritable the last few days, might this be a symptom of lowish E? I know I feel more like I did before HRT so I guess the answer could very well be yes. Fortunately I see my endo next Monday, hopefully it will be time for the next implant...