My ferritin levels, after been diagnosed with M.E many years was 10. I experienced thinning hair, eventually losing 50% of my thick hair. An eminent PhD trichologist( who has written papers on the subject) told me ferritin levels for females need to be at 150 for good follicle growth. I’ve had to take iron for most of my life. If I stop, my levels return to low range. You can still suffer with symptoms with low iron stores, despite haemoglobin levels being sufficient/ not anaemic.