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Diagnosis
How is PNH diagnosed?
Your specialist will examine you and arrange for you to have a urine test to check for haemoglobin in your urine. They can also do blood tests to assess your general health including a full blood count (FBC) to check if you are anaemic. They can also do kidney and liver function tests.
To confirm you have PNH, your doctor will send a sample of your blood to a specialist laboratory to check whether it contains any PNH blood cells using a test called “flow cytometry”. This shows the percentage of red and white PNH cells in your blood. It is more accurate for white blood cells during or just after you have had an episode of haemolysis or a blood transfusion.
Tests used in the treatment of PNH
Abdominal ultrasound scan
This scan of the abdomen checks for blood clots affecting the liver which can sometimes occur without symptoms.
Bone marrow examination
This is a test to evaluate the overall bone marrow function. This test involves a large needle being inserted into the rear pelvic bone to extract a sample of bone marrow. This test can be uncomfortable and sometimes painful, however pain relief can be provided.
CT scan
This test involves lying on a bed whilst a radioactive liquid is inserted into a vein in the arm. Photos of the chest are then taken in order to look at internal organs and also to rule out any blood clots.
D- dimer
This is a laboratory test to identify if someone has a blood clot.
Echocardiogram
This is an ultrasound scan of the heart which investigates the possibility of raised blood pressure in the lungs. If the blood pressure in the lungs is raised this could be caused by a possible blood clot.
Flow cytometry
This blood test is a commonly used to identify the proportion of PNH blood cells (red cells and white cells).
Video: Understanding the Role of Flow cytometry in PNH and Aplastic Anaemia watch Here
The standard way to diagnose PNH is by flow cytometry analysis of circulating red blood cells or granulocytes (a type of white blood cell) from a blood sample. The same test, if abnormal, can tell us something about the cause of bone marrow failure in some patients with aplastic anemia. A different type of flow cytometry test, typically done on bone marrow, can give some indication whether such patients are tending towards myelodysplasia instead.
Dr. David Araten (New York University) discusses the importance of flow cytometry in relation to PNH and aplastic anemia. He also talks about the latest research in flow cytometry in patients and other research that is currently on the horizon.
Full Blood Count (FBC)
These are routine blood tests which capture important measurements for PNH patients such as haemoglobin (HB), red blood cells (RBC), white cells and platelets
Kidney Function Test
As PNH can cause kidney problems, PNH patients should have their kidney function measured by blood tests.
Lactate dehydrogenase (LDH)
LDH is tested frequently in PNH patients. It gives an idea of how much haemolysis is occurring in the body. This is a common measurement used in clinical trials for new drugs to treat PNH to understand how effective they are.