Diagnosis
How is polycythaemia vera diagnosed?
Further tests are however needed to confirm a diagnosis of PV. The decisive factors in the blood count are the haematocrit and haemoglobin levels. To further clarify or confirm the diagnosis, examination of the bone marrow and genetic testing for relevant mutations are generally carried out. Imaging procedures such as ultrasound are also important to assess any enlargement of organs (e.g. the spleen).
When evaluating the level of risk to the patient, the assessment of cardiovascular risk and physical examination are likewise significant factors.
• Medical history
- Previous symptoms?
- Existing risk factors for complications with blood vessels?
- Existing heart or lung disease?
• Physical examination
- Size of spleen and liver?
- Indicators for circulatory disturbances?
- Indicators for heart or lung disease?
• Blood tests (laboratory values)
- Blood count: haematocrit level, number of the different blood cells, determination of haemoglobin levels
- Clotting parameters
- Iron levels
- Liver values
- Inflammation parameters and any other parameters
• Examination of organs
- Ultrasound of abdomen (liver, spleen)
- Cardiac function (ECG)
- Pulmonary function
• Bone marrow aspiration
- Microscopic examination of the bone marrow extracted
• Check for the presence of a mutation in the JAK2 gene, with testing of the blood or bone marrow
The blood test measures the haematocrit level and the individual number of the three different types of blood cells: red and white blood cells and platelets.
With polycythaemia vera all 3 cell lines are basically elevated, but the actual extent varies between patients and is not always clear at the initial stage.
The decisive factors for diagnosis are the haematocrit level and the number of red blood cells with their haemoglobin content.
It is however necessary to monitor cell numbers at regular intervals as they can change over the course of the disease and so affect the treatment required. Other key values that may be associated with the disease are for example iron levels and certain liver values.
A bone marrow examination is essential if a patient’s blood test results are borderline or unclear. In addition, examination of the bone marrow is the only way of determining whether its transformation to connective tissue has possibly already taken place in a patient with PV (secondary myelofibrosis). A bone marrow test is likewise also helpful in reliably distinguishing polycythaemia vera from other diseases categorised as similar in nature (essential thrombocythaemia, myelofibrosis), in which changes to the blood cells also occur. To examine the bone marrow, the doctor first administers a local anaesthetic
and then uses a special needle to remove a tissue sample from inside a bone, generally the pelvic bone. This tissue sample is dyed and examined under the microscope by a specialist. It normally results in a clear-cut diagnosis.
Blood samples can be used to perform a molecular biological test for genetic mutations.
A JAK2 mutation is found in 98% of all patents affected by polycythaemia vera².
It does not however just occur in such patients but also in those with the other two MPN diseases, albeit to a far lesser extent.
ˮThe JAK2 mutation (Janus kinase 2) is identified by special laboratories using molecular biological (genetic) methods. They often merely check whether the mutation is present, in other words yes or no. If required however, they can also perform differentiated measurement, i.e. determining the quantity of altered JAK compared to the normal quantity. This allows estimates to be made regarding the risk of certain diseases developing, e.g. the risk of thrombosis or bleeding.“
SUMMARY
The diagnosis of PV is confirmed subject to the following criteria (according to WHO 2022)¹
• Blood count:
Haematocrit level of at least 48% for women and at least 49% for men or
haemoglobin of at least 16.0 g/dl for women and at least 16.5 g/dl for men
• Bone marrow examination:
Increase in all three cell lines that is not age-appropriate (red and white blood cells, platelets) with characteristic changes in the appearance of the cells
• Genetic testing:
Presence of mutations in the JAK2 gen
PV is a chronic disease that generally needs to be treated throughout a patient’s life.
As its progression varies between patients, it is important to assess the situation of each person individually.