Platelet donors may donate up to 24 times a year with a minimum interval between
donations of 14 days.
How long does a platelet donation take?
A platelet donation takes up to 90 minutes. You will be asked to undergo a Donor
Health Check (as with blood donation) first and encouraged to have a short rest
and drink afterwards. You can expect to the whole process to take up to 2 hours.
Are the donor eligibility criteria the same for platelet and blood donors?
Eligibility criteria in terms of age and health are the same for blood and platelet donors, but for platelet donation we need to assess your height and weight ratio to check your blood volume - for more information click here to see the matrix. There is one additional medication rule: you cannot donate platelets if you have taken aspirin, aspirin-containing medications, piroxicam or nonsteroidal anti-inflammatory drugs, such as Ibuprofen in the last 48 hours. This is because these drugs affect the potency and performance of your platelets.
Once I start donating platelets, can I still donate blood?
Once you join the platelet panel, we ask you to give platelets only. This helps
us maintain our supply of platelets to patients by having a panel of committed donors
on whom we can call. If you wish to return to donating blood after donating platelets,
then you will need to wait 4 weeks before donating blood.
What if I change my mind about donating platelets?
You can change your mind at any time. If you do decide that platelet donation is
not for you, we hope that you will continue to give blood donations.
Is platelet donation safe?
Yes. Platelet donations are performed in a highly-controlled, sterile environment
by professionally trained staff. All platelet collection equipment is sterilized
and equipment that is in contact with the donor's blood is used only once, eliminating
the possibility of transmitting any viral infection.
Selected platelet donations - why are you special?
1. What are selected platelet donations - why are you special?
Some donors have a feature of their donation which is rare and difficult to find in the population of eligible donors.
In the case of certain donors they have a special tissue type which is often used to select ('match') platelets for transfusion
in patients where regular platelet transfusions haven't worked. Some parts of your tissue type is identical so less variable,
meaning your donation can be used to match against more patients, we call this homozygous. We refer to these donors as
'high-value' and you may have received a letter about this or hear this phrase used when you donate.
2. What is a tissue type?
Your 'tissue type' is also known as your HLA type. It is one of the ways that your body's defence system identifies the
differences between your own cells and foreign cells.
3. What is HLA (Human Leucocyte Antigen)
Antigens are proteins, often found on the surface of cells. Antibodies are formed by the body when it recognises a
'foreign' antigen. This is part of the body’s defence mechanism against 'foreign invaders'. These antibodies will destroy 'foreign'
antigens and the cells they are on. The surface of almost all cells including white blood cells and platelets (but not red cells)
carry a set of antigens called Human Leucocyte Antigens (HLA).
Your HLA antigens are determined by the HLA genes you inherit from your parents. There are a number of these HLA genes in
various combinations that make up your HLA type, consequently there are thousands of different HLA types in the population.
Some HLA types are found in populations throughout the world whilst others are found more commonly in particular ethnic groups.
The majority of people have 4 different HLA antigens which make up the tissue type on their platelet but some people have only
2 or 3 antigens. Platelets from donors with 2 or 3 antigens will match many more patients than those with 4 antigens and for some
patients only platelets with 2 antigens are suitable.
4. Who needs selected (HLA matched) platelet donations?
Patients who require multiple platelet transfusions, such as people with leukaemia, those on long term chemotherapy or with
platelet disorders, may develop antibodies to platelets that have different tissue types (HLA) to their own. This means that the
patient’s antibodies will destroy any platelets that are different from their own, as a consequence the platelet transfusion is
'rejected' and the transfused platelets are destroyed.
When a patient has developed HLA antibodies, we have to select donors who have an HLA type that matches the patient's own HLA
type and that is not seen as ‘foreign’ to the patients immune system.
Not everybody develops antibodies and the reasons why this happens are not always understood but patients who receive more
platelet transfusions are more likely to develop antibodies. The majority of patients don’t have antibodies that destroy platelets
and so don't need to be matched.
Patients often need platelets unexpectedly and at short notice. The life of a platelet is very short and some patients often
need platelets every day or every other day in order to prevent serious bleeding. We must maintain a stock of platelets with a
variety of HLA types at all times to ensure we can provide them for patients whenever they are needed.
5. Why is HLA type important?
When a patient has a platelet transfusion the transfused cells may be seen as foreign and produce antibodies against the HLA type.
In patients that have repeated transfusions the likelihood of producing antibodies increases.
If a patient makes antibodies to an HLA type then platelets have to be selected (or matched) so they are similar to the patients
HLA so the antibodies will not recognise them as foreign. If the transfusion isn't matched then the platelets will be destroyed
by the patient’s antibodies before they have a chance to work by stopping or preventing bleeding.
Finding a perfect HLA match is not always possible for some patients for a number of reasons. In these cases we select the
best match we have. Donors who have an HLA type that is homozygous will match more people and therefore their platelets are more
likely to be selected for these patients.
6. What does homozygous mean?
You may here the term homozygous used in relation to special donors, this refers to people who have inherited the same HLA
antigens from both parents and so they have a double dose of that anitgen instead of 2 different antigens, as a result your HLA
type is less variable. HLA selected platelets from homozygous donors are less likely to trigger antibody production after
transfusion, or be attacked by antibodies that already exist in the patient.
7. Why is homozygous "high value"
Homozygous donors are rare and although different homozygote tissue types will occur at different frequencies on average only
1 in 200 donors are homozygous.
8. What does this mean for me?
If you are found to be either homozygous or half-homozygous then your donations are extremely useful for certain patients. It has
no implication to you directly as everybody has an HLA type. We just wanted you to know how your donations are especially
needed. We hope you are able to continue donating as an apheresis platelet donor as often as you are able. Thank you for your
continuing support in helping us supply your life-saving platelets to hospitals.
Please ask a nurse when you next donate.