How muscle wasting conditions are diagnosed

Symptoms of a muscle wasting condition may appear at birth, during childhood, or at an older age. This often depends on the condition, but the age symptoms start can also vary between people with the same condition.

Speak to your GP if you’re worried about any symptoms in you/your child. These may include:

• Muscle weakness, tiredness or pain
• Seeming clumsy or falling over often
• Struggling to run, jump, or get up from the floor or a chair
• Finding it hard to walk or climb stairs
• Difficulty lifting things or holding your arms up
• Delayed motor milestones in babies or young children – for example, not sitting, crawling, or walking at the expected age

Your GP will ask about any symptoms. They may undertake an examination to check how you/your child move, looking for signs of muscle weakness, and testing your reflexes.

Give the GP as much information as you can about the symptoms and when you first noticed them. It’s important to tell them if you/your child have a family history of a muscle wasting condition. This is because many muscle wasting conditions are inherited and can run in families.

If your GP thinks it might be a muscle wasting condition, they will make a referral to a specialist. This may be a doctor who specialises in genetics (geneticist) or muscles and nerves (neurologist).

The specialist will carry out an examination and will ask about symptoms and family history. They may also offer some of the tests described on this page.

For some people, diagnosis can take a long time. This can be difficult but we’re here to support you.

Your doctor will offer tests to help diagnose a muscle wasting condition. They will explain which tests you/your child may have and how they can help with diagnosis. Speak to your doctor if you have any questions about what the tests involve.

CK test 

This may include a blood test to check for a protein called creatine kinase (CK). This is called a CK or CPK test.

CK is normally found in your muscles. If muscles are damaged, CK can pass into the blood. Some muscle wasting conditions cause raised CK levels in the blood, but not all. Exercise, some medicines, and other health conditions can also cause higher levels of CK.

Muscle wasting conditions cannot be diagnosed with a CK test alone, other tests will also be needed, such as a genetic test.

Genetic testing

Genetic testing uses a blood sample. The test looks for changes in short sections of DNA, known as genes. Your doctor may test for single genes that cause a certain muscle wasting condition. Or they may test for a group of genes (a panel) that are linked to some muscle wasting conditions. For example, the Limb Girdle Muscular Dystrophy Panel tests for several types of the condition at once. These tests can take a long time, especially when a panel is used.

Knowing which gene is changed, and what type of change it is, can help diagnose a muscle wasting condition.

Sometimes, symptoms, family history, or CK test results can suggest which condition you/your child might have. Your doctor can test for changes in the gene that causes that condition. For example, if they think it may be Duchenne muscular dystrophy, they will look for changes in the dystrophin gene.

Your doctor may do other tests first if they need more information about which genes to test. For example, they may offer a muscle biopsy or an MRI scan.

Genetic testing can help you/your child get the right management and support. Your doctor may make a referral to a genetic counsellor before or after tests. A genetic counsellor is a health professional who provides support, information and advice about genetic conditions. They can help with understanding how a condition is inherited and how it may affect other members of the family.

Magnetic Resonance Imaging (MRI)

An MRI is a scan that takes pictures of muscle, fat, and bone inside the body. It can show where muscle has been damaged or replaced by fat. Some muscle wasting conditions show certain patterns of muscle and fat, which can help with diagnosis. You may find it helpful to ask your doctor to talk you through your/your child’s MRI images, to help you understand what it shows.

Your doctor may use an MRI scan with other test results to diagnose a muscle wasting condition. It can also help show which muscles are best for biopsy.

Muscle biopsy

A biopsy involves taking a sample of muscle through a small cut or with a hollow needle. This is usually from your leg or arm. An injection of local anaesthetic will be given, which numbs the relevant area. This means you/your child will not feel the biopsy being taken.

After the biopsy, a doctor will use a microscope to look for any changes in the muscle sample. They will also test for muscle proteins that are missing or changed. The results may show whether you/your child have a muscle wasting condition.

Biopsies are used less often now that genetic testing has become more common. But they can be helpful if genetic testing has not shown which condition you have.

Muscle and nerve tests

Your doctor may offer muscle or nerve tests.

Electromyography (EMG) is a test where a small needle is gently placed into your muscles to check their electrical activity. Nerve conduction tests use small sticky patches on your skin to send mild electrical signals and see how fast your nerves respond. The doctor looks at the activity when you’re resting and when you’re moving.

The tests cannot tell which condition you have. But they can show whether the muscles and nerves are working as they should, which helps doctors understand where the problem is coming from.

If you/your child receive a diagnosis, your healthcare team will work with you to plan how best to manage your/your child’s condition and support wellbeing. This might include managing symptoms, accessing therapies, and getting advice on living well with a condition.

We have a list of conditions with detailed information on specific muscle wasting conditions.

You can also contact us anytime for information, support, and to connect with others who understand what you’re going through.

Sometimes, even after many tests, a specific diagnosis may not be found. This can happen because some muscle wasting conditions are very rare or hard to identify. We know this can be difficult and frustrating. It does not mean that your symptoms are not real, and help is still available.

If you/your child have a muscle wasting condition, but do not have a specific diagnosis yet, it may help to carry our undiagnosed muscle wasting condition alert card. This wallet-sized card explains that you have a muscle wasting condition and includes key information to help healthcare professionals provide safe, appropriate care in an emergency. You can order or download it from our alert card page.

If you’re unsure what to do next or need support, you can get in touch with us for advice and information.