Chronic Myeloproliferative Disorders and CML Flashcards
What are chronic myeloproliferative disorders?
Malignant clonal stem cell disorders of the bone marrow
What are the 3 types of chronic myeloproliferative disorders?
o Polycythaemia Vera (PV)
o Essential thrombocytosis (ET)
o Idiopathic myelofibrosis (IMF)
What is the dangerous disease that 10% of chronic myeloproliferative disorders can transform into?
Acute leukaemia
What is polycythaemia vera?
A type of blood cancer that causes bone marrow to make too many RBCS. These excess cells causes your blood to thicken, slowing it down.
What are the symptoms of polycythaemia vera?
Insidious onset (symptoms are obscure and come on slowly)
o Itching (aquagenic – hot baths) o Plethoric face o Headache, muzziness (due to increased viscosity of blood) o General malaise o Tinnitus o Peptic ulcer o Gout (due to increased RBC turnover) o Gangrene of toes
What is the cause of gangrene in polycythaemia vera?
due to increased risk of thrombotic events due to viscosity of blood
What are the 3 main signs of polycythaemia vera?
o Plethora (fullness of the face)
o Engorged retinal veins
o Splenomegaly
How is polycythaemia vera diagnosed?
Persistent increased Hb/haematocrit >0.5 (on 2 occasions)
What is haematocrit?
the ratio of the volume of red blood cells to the total volume of blood.
If a patient does have polycythaemia after a haematocrit test, what are the 2 next questions to find out?
- Relative or absolute polycythaemia?
2. 1ary or 2ary polycythaemia?
What is extremely important when determining the type of polycythaemia?
Detailed history and examination important!
What is relative polycythaemia?
loss of plasma volume causing an elevated haematocrit
What is absolute polycythaemia?
increase in red cell mass from any cause
What are the causes of relative polycythaemia?
Dehydration; often caused by loss of body fluids, such as through burns, dehydration, and stress.
Alcohol excess, unwell, diabetic ketoacidosis
What 4 first line tests are performed when diagnosing the type of polycythaemia?
- FBC
- Ferritin
- EPO level
- U&Es/LFT
Describe the EPO level in 2ary vs 1ary polycythaemia?
- 2ary polycythaemia driven by hypoxia (kidney makes more EPO so level is increased)
- 1ary polycythaemia; bone marrow itself is abnormal and makes more RBCs, causing EPO to be suppressed
Why is the EPO suppressed in 1ary polycythaemia?
bone marrow itself is abnormal and makes more RBCs, causing EPO to be suppressed
What is the majority of 2ary polycythaemia driven by?
Hypoxia
What are the 3 main 2nd line tests done in polycythaemia if the EPO is elevated?
- CXR
- USS abdomen
- ABG (arterial blood gas)
If an ABG shows hypoxia when investigating polycythaemia, what does this reveal?
2ary polycythaemia
What 2nd line tests are done in polycythaemia if the EPO is normal or low?
- JAK2 mutation
- Bone marrow examination
- EXON12 mutation
What is the JAK2 mutation? How can it lead to polycythaemia?
o Causes mutation in Janus kinases (JAK2) –> single point mutation
o This causes the receptor for EPO is permanently switched on, causing constant production of RBCs
o The presentation of the JAK2 mutation in peripheral blood DNA is diagnostic of a myeloproliferative disorder
What is the cause of primary polycythaemia?
Polycythaemia vera
What are the categories of causes of 2ary polycythaemia?
o Central hypoxic process o Renal disease o EPO producing tumours o Drug associated o Congenital
What are the causes of hypoxia that can lead to2ary polycythaemia?
- Chronic lung disease
- Right-to-left shunts heart disease
- Carbon monoxide poisoning
- Smoker
- High altitude
What drugs can lead to 2ary polycythaemia?
Treatment with androgen preparations (seen in bodybuilders)