How is FCS diagnosed and treated?

How is FCS diagnosed?

FCS can be diagnosed with blood samples. These will be a creamy colour when blood triglycerides are very high, and triglycerides levels are usually over about 10mmol/litre in people with FCS.

These days, more and more people are being diagnosed using a genetic test. These tests looks for faults in the genes that code for lipoprotein lipase and the proteins that work with it.  

When is FCS usually diagnosed? 

Most people with FCS are diagnosed as babies or young children, before the age of 10. This is because they have symptoms such as tummy pain, pancreatitis and fat-filled spots on the skin. For other people, the symptoms appear later so they’re diagnosed later, in their 20s, 30s and 40s.

Some women only show symptoms during pregnancy, when blood fats naturally rise. During pregnancy, if you have FCS, your blood fats will rise even higher.

Because FCS is so rare, some people don't get a diagnosis until they are teenagers or adults, even if the symptoms start in childhood. Sometimes people live with the symptoms for years, and sometimes people are misdiagnosed.

Learn about FCS, its causes and symptoms


Treatments for FCS

Medicines for FCS

The medicines which are usually used to lower blood fats, such as statins and fibrates, don’t help with FCS. That’s because they depend on lipoprotein lipase working properly.

There are some medications available but they only have a small effect. New medicines for FCS are being researched and developed at the moment.


Volanesorsen is a new treatment which can be used alongside a very low fat diet to lower triglycerides in the blood. You take it as an injection.

Volanesorsen works by lowering the levels of a protein in your blood called Apo-CIII. This protein normally raises triglycerides in a number of ways, including stopping lipoprotein lipase from working properly, mean triglycerides can't be cleared from your blood properly. 

Living with FCS

Dealing with your diagnosis

FCS can have a big effect on your life. Getting a diagnosis and living with the symptoms can be hard. Some people say they feel very low, anxious or depressed.

People with FCS will often have episodes of pain and pancreatitis throughout their lives even if they stick to a low fat diet. These episodes can come on without warning, and pancreatitis can leave you tired or fatigued for a long time afterwards.

It’s important to acknowledge how FCS affects you and how you feel about it. This is a big part of accepting it and being able to move forwards with your life.

Understanding your condition

One of the best things you can do to look after yourself is to get a really good understanding of how FCS affects you, what you can and can’t eat, and anything else you can do to look after yourself. It can give you the motivation and knowledge to choose and stick to the foods that will keep you healthy. 

Eating a very low fat diet

A low fat diet is the key to living with FCS and keeps the chances of pain and pancreatitis as low as possible. It can be very challenging because food is such a big part of our lives, and our social lives too.

Get practical information about eating for FCS 

Looking after yourself 

As well as eating a low fat diet, taking care of your body in other ways will lower the risk of diabetes, heart disease and other conditions. Keeping to a healthy weight, being physically active, avoiding alcohol and avoiding smoking will all help to keep your blood fats and blood pressure healthy.

Working with your doctor

Because FCS is so rare, most consultants only ever see a few people with it. You are the expert on your own body, and with time you will become an expert in FCS and how it affects you. Work with your specialist doctor to find the diet and treatments that work best for you. 

You are not alone 

FCS is very rare. Only around 55-110 people in England have it.  This means people don’t understand it which can feel very isolating, especially when combined with having to eat different things.

The truth is you are not alone. There are other people with FCS and other conditions which affect what you can eat. There are also people you can talk to help you deal with your condition and the changes you need to make.

  • Speak to your specialist doctor or nurse. They are experienced in working with people with blood fat conditions and can talk to you about what it’s like for you and things that can help.
  • See a counsellor, therapist or coach. This can give you the chance to speak to someone about how your condition is affecting you and find strategies to deal with it. Some people find Cognitive Behavioural Therapy (CBT) helpful.

    Speak to your GP about what’s available on the NHS or visit the British Association for Counselling and Psychotherapy.


Getting advice for women

FCS affects women differently to men because of the differences in our hormones. If you are female, speak to your specialist doctor about any medicines which might not be suitable for you, such as contraceptions and hormone replacement therapy (HRT). Also let them know if you are planning to get pregnant, as this can raise your blood fats further. 

If your child has FCS

If your child has FCS, they will probably be referred to a pediatrician (a doctor who specialises in working with children) with knowledge of blood fat conditions. They will be able to talk to you about how to keep your child healthy throughout their lives.  

Learn about eating a very low fat diet for FCS


Raising awareness

At HEART UK we are calling on the government and NHS to improve awareness of FCS and improve access to services and support; including dietetic, emotional and mental health support.

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