I'm awaiting results of my BMB, have already had negative blood tests for MPL, Jak2, BCR and Calr. I had a colonoscopy a couple of years ago and a mammo this year. I've had 400+ platelets since 2014 (highest 524 in 11/22). Iron is OK. My Haem said that if an underlying cancer was the cause, it would have manifested itself by now.
I think I misunderstood the purpose of having a BMB - I thought it was to hopefully rule out having a MPN - but having looked at the criteria for diagnosis I see that it's one of exclusion & that if no underlying cause of high platelets, then you're assumed to have ET.
Can I therefore assume that no matter what, I do 'at least' have ET? My Haem mentioned something about some people just naturally having high platelets without an MPN, but that really doesn't fit with the criteria.
TIA
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Alicay
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Hi Alicay, I am in a similar situation to yourself in that my platelets run slightly high, usually in 500’s, I’ve also tested negative for the main gene drivers and also had a colonoscopy and endoscopy. Any talk of a BMB is “on-hold” for me at the moment though as I am iron deficient (but not anaemic) so my Hemo wants to get my iron levels right before assessing again to see if a BMB is needed…
I have also thought along the same lines as yourself in the past as to whether “a diagnosis by exclusion” comes into play but I have decided that I will only accept the diagnosis of having ET if it is proven via positive gene driver tests or a positive BMB. For me, my gene tests are triple negative and if any future bone marrow biopsy proves negative too then I will be putting myself into the category of “someone with naturally high platelets”.
The WHO diagnosis for ET must meet certain criteria and in the absence of this criteria being met then I personally do not think anyone has the right to diagnose ET by exclusion. I want to see definitive proof from tests, but that’s just me and how my mind works…
There are bound to be people who will disagree with me but I find the best way to cope is to think that my platelets may naturally run high until it is medically proven otherwise.
The purpose of the BMB is to determine whether or not you have ET or another MPN. You are correct that there are some things that need to be ruled out, but there are also elements that need to be ruled in. All of these elements matter. You must meet four of them.
The 2016 WHO criteria for ET.
1 BM biopsy showing proliferation mainly of the megakaryocyte lineage
2 BM biopsy showing proliferation mainly of the megakaryocyte lineage with increased numbers of enlarged, mature megakaryocytes with hyperlobulated nuclei. No significant left-shift of neutrophil granulopoiesis or erythropoiesis and very rarely minor (grade 1) increase in reticulin fibers
3 Not meeting WHO criteria for BCR-ABL1 + CML, PV, PMF, MDS, or other myeloid neoplasms
4 Presence of JAK2, CALR or MPL mutation
or - Presence of a clonal marker (e.g., abnormal karyotype) or absence of evidence for reactive thrombocytosis.
You cannot assume anything. That is what the testing is for. It may involve additional testing to rule out all possible causes of reactive thrombocytosis.
It is true that some people just run a little high on PLT without evidence of a MPN. One of the reasons is Hereditary Thrombocytosis.
"Hereditary thrombocytosis (HT) is a familial myeloproliferative disorder with clinical features resembling sporadic essential thrombocythemia. In some families germline mutations causing HT have been identified in the genes for thrombopoietin (THPO) and its receptor, MPL." ashpublications.org/blood/a...
This is not to say that is what is going on for you. At this point, you really cannot know. I am afraid you will have to be patient as you go through the testing to get an answer.
The good news is that if you do have ET, it is a condition that can be managed. I was diagnosed with Et 31 years ago. It progressed to PV 9 years ago. I have lived a good life and at age 67 continue to do so. This is despite the MPN and other conditions including an arrhythmia and a brain tumor (both of which required surgery).
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From ET diagnosis to uncertainty !
MPN specialist says I “most likely do not have ET” and is not mandating BMB - need your thoughts 
How many had BMB prior to diagnosis uk
Understanding a MAYBE ET diagnosis
