I finally received a copy of my initial haematology appointment letter. No idea what numbers mean but understand they are still querying PV and Primary or Secondary Polycythaemia.
Sept 21 I had haemoglobin of 167g/1 & 48.5% haematocrit.
Jan 2022 haemaogloblin of 164g/1 & 45.9% haematrocrit
Are these numbers high? Is it good there is a little reduction?
JAK2 Exon 12 not detected however JAK2 V617F was an equivocal result so they have run JAK2 again with results due at my next appointment on 13 April. What does JAK 2 Exon mean?
Any advice would be appreciated. Next few weeks of uncertainty will be long
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LittleLuna
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They're in the way down👍My haemotologist likes my haematocrit below 45. As that reduces, so does your haemoglobin. Haematocrit is around 3 times higher than the value of haemoglobin.
I think my haematocrit was around 63 when I was admitted to hospital.
I can't help with the different Jak tests. I was just told mine was 47%, without any explanation.
That would mean that your mutant allele burden (variant allele frequency) is 47%. 47% of your hemopoietic stem cells (HSCs) show the JAK2 mutation. 53% are wild-type (normal). A higher allele burden tends to be associated with a higher symptom burden. People with ET tend to have the lowest allele burden, people with MF the highest, people with PV somewhere in the middle. Very broadly speaking, people with an allele burden <50% tend to have a more indolent presentation of the MPN. Emphasis on all of those statements is TEND. There is n hard and fast rule. There are are other factors that affect the presentation of the MPN, such as whether the JAK2 mutation is heterozygous or homozygous and the presence of non-driver mutations. The JAK2 mutated HSCs have a clonal advantage over the wild-type HSCs. Over time, allele burden will increase. This is relevant to the presentation of the MPN and the risk of progression.
The normal range for Hematocrit (HCT) varies by lab, but generally is 34.1% - 44.9% for females, and 40.1% - 51% for males. HCT is the % of your total blood volume comprised of red blood cells. The remainder is mostly plasma and the buffy coat (about 1% of blood volume comprised of platelets and white blood cells).
You are considered to have erythrocytosis if your HCT is above the reference range for your gender. Erythrocytosis can be primary (Polycythemia Vera) or caused by another medical condition (Secondary Polycythemia). There are also cases of Idiopathic Erythrocytosis and Familial Erythrocytosis.
Approximately 95% of people with Polycythemia Vera have one of the two known JAK2 mutations, JAK2v617f or JAK2 Exon 12. A small percentage are positive for the CALR mutation (that usually causes Essential Thrombocythemia). The remainer are people with PV who are negative for all known mutations. People with lower levels of JAK2 mutated cells will sometimes have equivocal test results. The test may need to be repeated. The next time it should also include checking the CALR mutation and if your platelets are also high the MPL mutation.
Erythrocytosis is a primary risk factor for thrombosis in PV. Erythrocytosis also causes your blood to be too thick (hyperviscosity) The primary measure in treating PV is to keep HCT<45% males, HCT<42/43% females. It is a good thing that your HCT moved in the direction of the normal range. Note that HCT does normally vary as it is influenced my more than just the number of red blood cells at any given time (e.g. plasma volume).
Generally for MPN patients the desired HCT (haematocrit) is the lower end of the normal range, for females, 42-43 so you have some more to go if you have PV.
I also had some reduction in HCT around the time of my Dx, before I started Hydrea therapy, but after starting asipirin; from 50.8 to 46.3 in two weeks. On hydrea it took only a week to go to 43.6, this is ok for male MPNs.
There are two typical types of Jak2 so all us Jak 2's have something on an Exon, but most usually Exon 14. Not detecting exon 12 is not too surprising even if a Jak 2 mutation
is suspected since most Jak2 problems are on exon 14.
<<The most frequently reported genetic aberration among polycythemia vera (PV) patients is a gain of function mutation V617F in exon 14 of Janus kinase 2 (JAK2) gene. However in many investigations, V617F negative PV patients have been reported to harbor mutations in JAK 2 exon 12>>
If you have 2ndary PV they won't find any defective Jak2's:
<< All the other patients with wild-type (normal) JAK2 and a normal or elevated EPO level have secondary polycythemia.>>
Also be sure to note Hunter's advice on CALR and MPL. These mutations are most often found in ET patients so if they suspect PV you're less likely to have; but you should check to be sure. You may also ask your Dr about nexgen sequencing, here they look for many other mutations, I had 54 searched. This is esp useful (necessary in my opinion) if things are still indefinite. NextGen is also for future reference if you have an MPN.
Thank you EPguy. You and Hunter have given me a wealth of info to bring to my next appointment. I am not on any meds. Registrar said they wanted further numbers from my 2nd JAK2 test to confirm PV and if it is then discuss treatment.
Thank you to everyone here who has been so supportive and you all have such a wealth of knowledge in what feels like a world I might never understand. So much to know.
My best friend has had ET since she was 21, now 51 and she is even learning as she has done this alone with no support network like you.
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