I am 75, have had an MPN since at least 2001, don’t have osteoporosis and have never heard of our MPN’s affecting bone density. Maybe because I haven’t had this particular problem. This may be another individualized way in which each of our bodies react to our disease. The more I learn from others here, the more clear it is that there is no “one size fits all”.

Dear Tina,

You are right, osteoporosis is a feature in MPNs. And given the fact that all MPNs affect the bone marrow and generate chronic inflammation, which in turn have been linked to bone density issues, it is surprising doctors do not tell patients about osteoporosis. I do remember my doctor during bone marrow biopsy making a comment that I had quite dense bones and they did not expect it in someone with MPN, but I was 38 years old at the time and was trying to train as much as my body allowed me.
https://pubmed.ncbi.nlm.nih.gov/34428274/
https://www.tandfonline.com/doi/abs/10.1586/174...

I discussed low bone density with my physiotherapist as asked by a neurologist I saw (I lost bone density in my cervical spine alone for some reason) and they gave me some advice. My health does not allow for most of what they recommend for increasing bone density, but gravity is a way to try to reduce the loss of bone density, although there are limitations to this.
So if Tai Chi is something that you like and can do, that is only going to help. I am always for not letting better be the enemy of the good.

Solidarity 🌸

Myeloproliferative disorders and their effects on bone homeostasis: the role of megakaryocytes - PubMed

https://pubmed.ncbi.nlm.nih.gov/34428274/

There can be protective factors against osteoporosis one can benefit from. Some are genetic. So if one has the protective genes, they might not develop osteoporosis.
I have a gene that should protect against heart damage and after I had a mini heart-attack courtesy of Covid-19, an MRI of the heart 2 years later showed it recovered completely.
It is true that MPNs are quite heterogeneous, that there are many phenotypes, but it is also true that factors outside of our MPNs can influence our MPNs, such as other genetic factors or even simple things like adequate access to good health care and socio-economic factors like wealth.
I am eager to see better studies on different types of genetic mutations leading to MPNs, protective factors against different outcomes, mechanisms behind progression, phenotyping based on mutation and symptoms. Because as it is now, everything seems like a lottery and very individual. Which is partially true, but there is more beyond individual symptoms that could help with targeted treatment for ET, for example.

Research shows that it was tested on mice and showed the link to MPNs. Here is another study:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC53...

Polycythemia is associated with bone loss and reduced osteoblast activity in mice

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5319412/

I do hope we are headed in that direction!