Ever wondered what happens to your blood after you’ve donated? We found out
If you’ve ever given blood, you’ve probably eaten a biscuit straight after and then gone about your day.
But what happens to your blood after it’s been removed from your body is truly fascinating.
Metro went behind the scenes at a blood manufacturing site in Colindale, north London, one of three such places across the UK.
We followed the journey donations go on, through freezers, high-tech machines, and across countries, all in order to save lives.
In the lab, scientists work around the clock to extract the ‘liquid gold’ in a little-known process vital to the future of the NHS.
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As many as 2,000 bags of whole blood arrive at the doors of NHS Blood and Transplant’s Colindale hub every day.
The race is then on to process the packs within 27 hours of donation to maintain the quality of the final products.
One of these is red blood cells, which are used to treat people who have suffered blood loss, trauma and surgery.
But 55 per cent of our blood is a yellowish fluid called plasma.
Dubbed ‘liquid gold’, it contains vital antibodies that can be made into medicines that save and improve lives. But that is a few steps away.
Your 470ml bag of blood is firstly strung up and filtered to remove the white blood cells, which fight infections and foreign invaders.
Staff – often working throughout the night – then place the filtered blood into a large spinning machine called a centrifuge.
Once your bag is spun around, you’ll suddenly see the yellow plasma has separated from the red blood cells.
A fancy press is used to pump these two products into different bags.
Those red cells are then stored at 4C until test results – taken when you give blood and analysed in Bristol – confirm the blood is safe to give to hospitals.
When your blood is used, you’ll get a text saying which hospital your blood went to.
Your plasma, on the hand, needs to be blast frozen in a rapid freezer, reaching -20C in one hour.
Some of those bags of plasma are also sent to hospitals to help treat severe bleeding.
But the other bags of plasma get a whole lot chillier, as they are destined to be made into crucial new medicines.
Plasma is used to produce – long word incoming – immunoglobulins, which treat more than 50 devastating autoimmune conditions, as well as albumins, which treat severe burns and traumatic injuries.
More than 17,000 people rely on immunoglobulins every year.
Up until 2021, there was a 25-year ban on plasma from Brits being used to create these medicines because of concerns around ‘mad cow’s disease’, or Creutzfeldt Jakob Disease.
In March last year – four years after that ban was lifted – the first immunoglobulins from a UK donor went into the arms of an NHS patient.
But the health service doesn’t yet have the tech to process our plasma into these small vials of medicine, so they have to be shipped to Europe instead.
So while the bags of plasma wait to leave the UK, they are kept at a bone-chilling -40C, which requires industrial-sized coats and gloves to stop workers – and the odd journalist – from being frozen stiff.
Once the removal van arrives, staff at the Colindale hub have just minutes to move boxes of plasma into mobile freezers, which will drive them out of London.
Thousands of vulnerable NHS patients have now received life-saving medicines made from British-donated plasma since March 2025.
Despite this success, the UK is still more than 75% reliant on immunoglobulin from other countries.
Jan Majkowski, who is Plasma Performance and Efficient Lead at the Colindale site and showed Metro around, said: ‘Plasma is instrumental to the process of blood donation and blood services.
‘The fractions of plasma are invaluable. They are critical in treating rare diseases and common diseases like haemophilia and immune diseases.
‘The only support for these people is to receive these plasma transfusions.’
NHSBT say they still need more donations to make the health service more self-sufficient.
It is an important part of the government’s 10 Year Health Plan ambition to build an NHS that is resilient to shocks by reducing the UK’s dependence on imported medicines.
It will also be crucial to the around 17,000 NHS patients who rely on plasma-derived immunoglobulin every year.
There are even plasma-only donation centres, located in Birmingham, Reading and Twickenham, which means donors can come back every two weeks instead of the normal four for blood donors.
Your bag of plasma also has other purposes too.
Sometimes it will be thawed for more than 16 hours to form vital clotting factors, which are separated from the plasma and used to treat bleeding disorders like haemophilia.
The Colindale blood hub can take fragments in our blood – called platelets – and combine them for use in cancer treatments and surgical procedures.
These platelets have to be kept on constantly moving agitators to keep them viable.
As many as 800,000 people donate blood every year, but more are still needed.
NHSBT analysis revealed last year that there is an annual shortfall of over 200,000 donors to meet growing demand.
The NHS urgently needs more donors of Black heritage, because they are more likely to have the Ro blood subtype which is vital for treating sickle cell disorder.
Sickle cell is most common amongst people from Black African, Black Caribbean and Mixed heritage.
Get in touch with our news team by emailing us at webnews@metro.co.uk.
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