APL symptoms and tests

The main symptoms of APL happen because someone does not have enough healthy blood cells.

Symptoms of APL can include:

• bruising easily
• bleeding easily or for longer.  This can include things such as bleeding gums, frequent nose bleeds or heavier menstrual periods.
• blood clots – you may experience symptoms such a painful or swollen leg and difficulty breathing
• blood in your poo - this could look black and tarry or bright red
• headaches, being sick or problems with your vision due to a blood clot or bleeding in your brain
• more infections or infections that are more severe or last longer
• tiredness or breathlessness because of a low level of red blood cells (anaemia)
• confusion, difficulty speaking or problems with your movement due to bleeding in your brain.

You may also have some weight loss.

It is important to tell your GP straight away if you have symptoms, you are worried about.  They’ll usually arrange for you to have a blood test.

Your GP will usually refer you to specialist for further tests and you may be admitted to a hospital urgently.

Your doctors can diagnose APL with tests looking at your blood, bone marrow and genes.

What you need to know:

• Tests to diagnose APL include blood tests, a bone marrow biopsy and genetic tests.
• Genetic tests confirm a diagnosis of APL as APL is caused by a faulty gene. It is important to note that APL cannot be passed on to children.
• APL needs to be treated urgently so treatment will usually start before a diagnosis is confirmed.

Your GP will usually arrange for you to have a blood test if you have APL symptoms. They may then refer you to a specialist called a haematologist if they think that you may have APL.

A full blood count (FBC) is usually one of the tests you will have. You may also have other blood tests. We have more information about blood tests.

It’s not normally possible to diagnose APL with just a blood test. There may be leukaemia cells in your bone marrow that aren’t in your blood yet. Your bone marrow is a spongy tissue found inside some of your bones, where the body makes blood cells.

Your doctors will usually take a bone marrow sample (a biopsy) to look at under a microscope to check for leukaemia cells.

Find out more about having a bone marrow biopsy.

Although the results of a full blood count and bone marrow biopsy may suggest that you have APL, your doctors will need to run a more tests on your blood and bone marrow samples to confirm a diagnosis.

These tests look at your genes are known as genetic tests. They look for specific changes in the chromosomes and genes in your abnormal blood cells. These tests help your doctors confirm a diagnosis of APL. They also help your hospital team to work out the best treatment for you.

If your doctor suspects that you have APL, you will usually start treatment before you’ve had all the tests and before your diagnosis is confirmed. This is to lower your risk of serious complications like bleeding.

APL can affect the way your blood clots and increase the risk of bleeding and blood clots. This means regular clotting tests are important. You’ll usually have these at least once a day in the early phases of your treatment.

Bleeding can become life-threatening if it’s not treated straight away, so your hospital team will monitor you closely for this. You may need daily transfusions with blood substances such as platelets or plasma to lower your risk of bleeding.

You’ll have a general health check to assess how you’re likely to cope with the side effects of APL treatment. This will involve a range of tests to check your heart, liver and kidney function. You may also be screened for other conditions. Understanding your general health helps your doctors to plan your treatment.

Ask your hospital team to explain why you’re having a certain test and what the results mean.

Your white blood cell count at diagnosis helps your hospital team decide which treatment is best for you. This will help them determine what they call your risk and help them choose the right treatment for you.

APL is categorised as low risk or high risk. If your white blood cell count is high, this is considered high-risk APL. Having a high risk does not mean that treatment will be less effective. Risk only helps your hospital team to decide how to treat you.

This information is accredited with the PIF TICK, the UK's only quality mark for trusted health information.

Last review February 2026. Next full review due February 2029. We may make factual updates to the information between reviews.

Thank you to Professor Steven Knapper and Carla Fitzpatrick, Clinical Educator for Haematology, for checking the clinical accuracy of this APL information.