For the longest time, there was, and I guess still is, a belief that calcium messes with the absorption of iron into the system.
If you rely on plant based protein, calcium prevents the substantial absorption of that. So, often we are told to stick to meat.
Then I guess more research supported the idea that while it has an effect on absorption, calcium does little to hinder iron stores.
The same advice continues to be given though: don’t take iron supplements the same time as you take calcium supplements and don’t take your iron with milk. I don’t think this applies to you though.
Low calcium is also possible from low protein levels in the blood. Not exactly iron but really bad (and related) anemia. How are your albumin levels? Again, for albumin levels to be good, you need a diet with proteins.
I am no doctor and I don’t even play one on tv but just throwing this out there. If your diet has been suffering lately, and you are a tiny gal to begin with, as well as dialysis wiping clean the good stuff too, you could have malnutrition.
I can attest it happens when a person is small framed.