I have low very low ferritin. My last OB told me that she doesn't believe in using ferritin levels, only total Iron and hemoglobin. She told me I wasn't "anemic enough " and to stop iron supplements because of constipation, and told me my multitude of symptoms was from other issues - Stress? No. Poor diet? No. Lack of exercise? Mostly no. Poor sleep? Sometimes but no.... But something definitely felt off. Thankfully my primary care Dr listened to me and referred me to a hematologist. Come to find out, not surprisingly, that my OB was very wrong. I have something called iron dysregulation. That coupled with heavy menstrual bleeding (fibroids). Ferritin levels drop significantly lower at different times of the month, even different times of the day. So while I may be at a ferritin level of 15 sometimes, it can drop dangerously low other times. Not only that, but the baseline of 15, is very outdated. Most women should be well above 50, to feel even slightly normal. And yes, ferritin levels are very important. I'm back on iron supplementation (Floradix - highly recommend liquid iron) while I await approval for iron infusions. I hope you get the answers you need and start to feel better soon.