I found this article from the mid-1980's mention anemia as a common co-finding with other better known PMR indicators. Somehow this seems to have totally fallen off the radar of the medical community in today's world. I suspect it is most likely more common than is currently recognized. It is articles like this that I have used to connect dots. I have several more dots - but it is a journey.
https://pubmed.ncbi.nlm.nih.gov/3710167/