polycythaemia vera Flashcards
definition
- often mutation in haematopotetic stem cell which causes overproduction of rbc
- this fsulty stem cell usually then proliferates making more
- overproduction of neutrophills and platelets often accompanies bc haematopoitic stem cell also makes platlets and wbc
- mostly caused by mutation of JAK2 98%
- these cells will then start to die out
- scar tissue forms
- bone marrow can no longer produce stem cells
- leading to anaemia, thrombocytopeania, leukopenia
- spent phase
- becomes myelofibrosis
absolute and relative
absolute - raised RBC
relative - dec blood plasma volume
absolute / secondary
2 ways:
compensatory - in hypoxia the kidneys release EPO which increases RBC production
abnormal - in abnormal conditions eg tumour
primary
caused by JAK2 which leads to constant activation of JAK2 - uncontrolled RBC production
what can be done to see if its primary or secondary?
erythropoiten levels
primary - low
secondary
- compensatory - mildly raised
- abnormal - very high
diagnosis criteria?
all 3 major
or
2 major and 1 minor
major parts of diagnosis criteria
- haemoglobin:
>16.5 male
>16 female
OR
haematocrit
>49% male
>48% female
0.35-0.45 - bone marrow tri-lineage proliferation with pleomorphic mature megakaryocyte
- presence of JAK2 mutation
minor point of diagnostic criteria
subnormal serum erythropoiten level
treatement
- aspirin 75mg daily (prevent clotting in spent phase and improve symtpoms)
- venesection on 2 occassions to reduce blood volume
- hydroxycarbamide 500mg daily - lowers blood cell production
- aim to keep haematocrit <0.45
- annual cardiovascular risk assessment
- ruxolitinib - JAK2 inhibitor - also relieve symtpoms
using treatments, what level do we want to keep the haematocrit at?
<0.45 - 45% of blood is meant to be rbc
key presentations
- itching worsenned by hot water bc of increased basophills and mast cells (more histamine)
- blurred vision
- fatigue, headache, dizziness
- eurthromegalia - burning in face hands and feet
- abdominal discomfort
- HTN
- haematosplenomegaly
- inc of uric acid - gout and kidney stones
more prone to blood clots
- pe
- dvt
- stroke
prognosis
if left untreated - survival of approx 8 months
JAK2 gene
- JAK2 is released by the kidneys when more rbc are needed in the blood
- it then acts on the haemtapoitic stem cells encouraging them to produce more
- once there is enough in the blood, it then unbinds and the kidneys don’t produce it
- when there’s a mutation with the JAK2 gene it is constantly bound to the haematopoitic stem cell
- meaning it therefore constantly is producing RBC
FBC + other test results
- high haem
- high haematopoitic
- high wbc
- high platelet
decreased erythropoitin (if jak2)
some may have high or normal levels
bone marrow examination + biopsy - signs of fibrosis
genetic testing
phlebotomy
removed from vein every few months
common cause of secondary polycythaemia?
anabolic steroid abuse - gym goers
