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How is PNH diagnosed?

Your specialist will examine you and arrange for your 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.


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).


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.



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