Polycythaemia Flashcards
Define Polycythaemia?
An increase in haemoglobin concentration above the upper limit of normal for a person’s age and sex
How is Polycythaemia classified?
Relative Polycythaemia = Normal red cell mass but low plasma volume
Absolute (True) Polycythaemia = increased red cell mass
What is the aetiology of Polycythaemia Rubra Vera?
Characterised by clonal proliferation of myeloid cells
They have varied morphologic maturity and haematopoietic efficiency
Mutations in JAK2 tyrosine kinase are involved
What are the two types of Secondary Polycythaemia?
Appropriate increase in erythropoietin
Inappropriate inrease in erythropoietin
What is the aetiology of Secondary Polycythaemia where there is an Appropriate increase in erythropoietin?
Due to chronic hypoxia (e.g. chronic lung disease, living at high altitude)
This leads to upregulation of erythropoiesis
What are the causes of Secondary Polycythaemia where there is an Inappropriate increase in erythropoietin?
Renal (carcinoma, cysts, hydronephrosis) Hepatocellular carcinoma Fibroids Cerebellar Haemangioblastoma Secondary polycythaemia may be due to erythropoietin abuse by athletes
What is the aetiology of Relative Polycythaemia?
Dehydration (e.g. diuretics, burns, enteropathy)
Gaisbock’s Syndrome
What is Gaisbock’s Syndrome?
Occurs in young male smokers with hypertension, which results in a decrease in plasma volume and an apparent increase in red cell count
What is the epidemiology of Polycythaemia?
Annual UK incidence: 1.5/100,000
Peak age: 45-60 years
What are the presenting symptoms of Polycythaemia?
Headaches Dyspnoea Tinnitus Blurred Vision Pruritis after hot bath Night Sweats Thrombosis (DVT, Stroke) Pain from peptic ulcer disease Angina Gout Choreiform movements
What are the signs of Polycythaemia on physical examination?
Plethoric complexion (red, ruddy)
Scratch marks from itching
Conjuctival suffusion (redness of the conjuctiva)
Retinal venous engorgement
Hypertension
Splenomegaly (in 75% of cases)
Signs of underlying aetiology in secondary polycythaemia
What investigations do we do for general Polycythaemia?
Investigations required for diagnosis
Isotope Dilution Techniques
What investigation do we do for diagnosis of Polycythaemia and what do we see?
FBC:
- High Hb
- High Haematocrit
- Low MCV
What are Isotope Dilution Techniques and why do we do it for Polycythaemia?
Allows confirmation of plasma volume and red cell mass
Distinguishes between relative and absolute polycythaemia
What investigations do we do for Polycythaemia Rubra Vera?
High WCC High Platelets Low Serum EPO JAK2 mutation Bone marrow trephine and biopsy shows erythroid hyperplasia and raised megakaryocytes