Ferritin is the marker that tells you what's actually in your iron stores, not just what's circulating in your blood right now. It's also one of the most misunderstood results on a blood test, since both a low reading and a high one can be telling you something important, and they don't mean the same thing.

If your thyroid results keep coming back normal but you still have every symptom of an underactive thyroid, fatigue, low mood, weight changes, cold hands, low iron could be part of why. Your thyroid needs iron to actually make and use its hormones, and this link rarely gets mentioned.

Being told your bloods are "normal" doesn't always mean your iron is where it needs to be for you to actually feel energised. There's a real gap between not being anaemic and having enough iron on board, and that gap is where a lot of unexplained fatigue lives.