All Blood types are needed, but as the case of Lucy Hill demonstrates, it is important to know your blood type!

Global support to give blood to a critically ill graduate in Thailand has prompted people to wise up about their blood type.

Lucy Hill, 21, from Bury, Greater Manchester, was seriously injured when her moped was in collision with a car in Chiang Mai and was desperately in need of rare A negative blood. Fewer than one per cent of Thai people have ‘negative’ blood types, making it difficult for medics to find a match.

Lucy has now had a potentially lifesaving blood transfusion and operation. Hundreds of westerners holidaying in Thailand came forward to donate blood after a social media appeal went viral.

People who are rare blood types are encouraged to carry this information on them, either in a medical locket or in a purse. But a lot of people do not know their blood type and wouldn’t be able to tell medics this vital information in an emergency - or know if they could help someone by donating their blood. So here’s what you need to know about blood groups.

What blood group are you?

Ask your doctor, he may have this information. If not a simple blood test will tell you. There are four main blood groups that are defined by the ABO system:

  • Blood group A has A antigens on the red blood cells with anti-B antibodies in the plasma
  • Blood group B has B antigens with anti-A antibodies in the plasma
  • blood group O has no antigens but both anti-A and anti-B antibodies in the plasma
  • Blood group AB has both A and B antigens but no antibodies

The most common blood group is ‘O’ - with almost half of the UK population being in this blood group. If a person receives blood from the wrong blood group it can be life threatening. Group A blood must never be given to a person with group B blood. Group O red bloods cell don’t have any A or B antigens and therefore can be given to a person in any other blood group.

The Rh system

Sometimes red blood cells have another antigen, a protein known as the RhD antigen. If you have the RhD antigen, your blood group is RhD positive and if you don’t, your blood group is RhD negative. This means that you can be one of eight blood groups.

  • A RhD positive (A+)
  • A RhD negative (A-)
  • B RhD positive (B+)
  • B RhD negative (B-)
  • O RhD positive (O+)
  • O RhD negative (O-)
  • AB RhD positive (AB+)
  • AB RhD negative (AB-)

Around 85% of the population is RhD positive, with 36% of the population having a blood group of O positive (O+). O negative (O-) blood can be safely given to anyone in most cases, and it is often used in emergencies when the blood type of a person isn’t known straight away. This blood is safe for most people because it doesn’t have any A, B or RhD antigens on the surface of the cells and it is compatible with every other blood group.

Giving blood

Most people are able to give blood, but only 4% actually do. You can donate blood if you:

  • Have a good overall level of health
  • Are 17 to 66 years of age (if it's your first time)
  • Weigh at least 50kg (7st 12lb)

Find your nearest Blood Donor Centre in England and North Wales and book an appointment online. You can also call 0300 123 23 23 to book an appointment. Blood group O is the most common blood group in the UK