Donner Sang Compter

Blood groups

In 1900, Austrian scientist Karl Landsteiner identified the ABO blood group system which consists of the 4 main blood types: A, B, O and AB, each being either rhesus positive (RhD+) or negative (RhD-).

Our blood type is hence determined by the 2 main antigens it contains; ABO and Rh, which combine to create the 8 blood types: O+, O-, A+, A-, B+, B-, AB+ and AB-.

The ABO system has associated anti-A and anti-B antibodies, antibodies being the body's natural defense against foreign antigens. These antibodies are found in the plasma of individuals according to their own blood type, and define, alongside one’s antigens, who they can give to and receive blood from. 

Note:

The O- blood type is called the universal donor, able to give to all blood types and the AB+ one the universal recipient, able to receive from everyone.

Nowadays however, the policy of hospitals around the country consists of transfusing a patient with blood from his own type, to minimize the risks encountered during blood transfusions, no matter how minimal they are.

Here’s a table chart summarizing the different possible combinations.

If your blood type is:

You can give to:

You can receive from:

O Positive

O+, A+, B+, AB+

O+, O-

A Positive

A+, AB+

A+, A-, O+, O-

B Positive

B+, AB+

B+, B-, O+, O-

AB Positive

AB+ Only

All blood types

O Negative

All blood types

O- only

A Negative

A-, A+, AB-, AB+

A-, O-

B Negative

B-, B+, AB-, AB+

B-, O-

AB Negative

AB-, AB+

AB-, A-, B-, O-

Blood components

Blood can be divided into red cells, white cells, platelets and plasma.

Following is a brief summary about their roles and use in donations.

Red blood cells:

  • Also known as erythrocytes.
  • Distribute the oxygen to our body tissues.
  • Carry the carbon dioxide back to our lungs.
  • Contain the iron protein.
  • Are regenerated every 120 days.

Red blood cell transfusions are used in cases where the patient has lost a lot of blood, like in trauma or surgery or childbirth but also in cases of severe anemia when the bone marrow does not produce enough of them in chemotherapy, leukemia and thalassemia.

The red cells are filtered to be separated from the white blood cells, and when well preserved, have a lifespan of 35-42 days from the day the donation was made.

White blood cells:

  • Also known as leukocytes.
  • Fight infections.
  • Part of our body's defense system.

White cell transfusions are rare, but could be needed for patients suffering from life threatening infections and whose natural defense mechanisms don't respond well to antibiotics.

Platelets:

  • Also known as thrombocytes.
  • Help the blood to clot.

Platelets transfusions are frequent among cancer patients and road accidents’ victims.

Plasma:

  • A yellow fluid that carries all the blood cells.
  • Contains the coagulation factors and immunoglobulins.

Plasma transfusions are used in conjunction with RBC transfusions, and among those who present with deficiencies in some coagulation factors.

Safety

Even though donating and receiving blood is an extremely safe procedure, there are always potential risks that need to be assessed and managed with regards to the patients and the donors.

Safety does not begin and end at the blood banks and hospitals, patients and donors have an important role to play as well.

The Donor Health Checklist (DHC) is designed to minimize the risk by spotting potential problems for donors and patients.

The DHC is our first line of defense, it is very important that you refresh your memory with it every time you want to donate as the safety rules or your personal circumstances may have changed. And of course, back in the labs the donations are tested to pick up any dangerous infections. Even with all these tests, we fail to detect some infections (especially if they are very recent) and this is why the DHC questionnaire is vital to us in order to spot a potential risk.

Tests on your blood

You may have noticed that each time you give blood samples are taken as well: these samples are used to complete some safety tests that are mandatory on every single blood donation whether this is your first donation or just one of the many you have given over the years. These tests play a very important role in ensuring a safe blood supply to patients, as they test for your blood group as well as infections that can be passed from donor to patient via a blood transfusion.

The tests that are conducted most often are the following:

Syphilis
Syphilis is caused by an organism called Treponema pallidum. Syphilis is usually a sexually transmitted disease which if untreated, can be serious. This disease is fully treatable with penicillin.

The tests we use look for antibodies, which can often be found in a person's blood long after the infection has gone. A positive test for syphilis usually relates to an infection in the past, but if the test is positive we are not able to use your blood.

Hepatitis B Virus (HBV):
This virus infects the liver; it can cause inflammation of the liver (hepatitis) and liver damage. Hepatitis B is very common in some parts of the world where it is often transmitted from mother to child at birth or in infancy. Most donors we identify have an association with those places and appear to have been infected since childhood or early life.

Our test looks for a substance called hepatitis B surface antigen, which is part of the 'coat' of the virus. If we find this substance in a donor's blood then further tests are performed to confirm the result. Most of the donors we identify are long - term carriers of the virus who feel completely well. Acute hepatitis B infection is uncommon in blood donors. Occasionally we get a positive result because the donor has recently had an immunization against hepatitis B and not because infection is present.

Human Immunodeficiency Virus (HIV):
This virus causes Acquired Immune Deficiency Syndrome (AIDS). Once an individual becomes infected with HIV then the virus remains in the body and eventually causes destruction of the immune system. It is mainly transmitted sexually, or from mother to baby, or by intravenous drug use. A person who has HIV does not necessarily have AIDS.

Our test looks for antibodies to the virus, but unlike many other infections the presence of the antibody shows that the virus is present, and not that the infection is in the past.

Hepatitis C Virus (HCV):
This virus infects the liver and can cause inflammation and liver damage. It is commonly transmitted by intravenous drug use. We have two kinds of test; a test for antibodies and a test for the virus. The test for virus is an extra safety test and can tell us whether a donor with antibodies is infected or not. Most of the donors we identify are long-term carriers of the virus who feel completely well.

Human T-Lymphotropic Virus (HTLV):
This virus infects white cells called T-lymphocytes, and can cause a neurological disorder called Tropical Spastic Paraparesis (or HTLV Associated Myelopathy) and Adult T cell Leukemia. It is relatively common in some populations and is thought to be transmitted mainly from mother to child at birth and by breast-feeding.

The test is for antibodies and a positive test means the individual is infected with the virus. Comparatively few infected individuals become ill and most carriers feel completely well.

Supplementary Tests:

These tests are not performed on every donation. Whether or not they are done depends on the donor's individual circumstances, in particular with reference to travel. Supplementary tests are also done to provide specifically tested blood for particular types of patient.

Malaria
Malaria is caused by a parasitic infection transmitted by the bites of Anopheles mosquitoes. The infection causes fever and is a major cause of death in some parts of the world. The test is for antibodies to the malaria parasite. A positive result does not necessarily mean that the individual has active malaria, merely that they have had malaria at some time in the past. The antibodies can disappear over time, so donors with a positive malaria antibody test are not necessarily unable to give blood in the future.

T Cruisi
This is a parasite called Trypanosoma cruzi. The parasite is found in certain parts of Central and South America and is transmitted to humans by biting insects or from mother to baby at the time of birth. Long-term carriers of the parasite are at risk of illness (also called Chagas Disease), due to destruction of the muscles in the heart and intestines. 
Not all carriers become ill.

Our tests look for antibodies, to the infection. A donor's place of birth and travel history determines whether the test is required.

Cytomegalovirus (CMV):
This is a very common virus which causes a mild 'flu-like' illness. Individuals in good health make a full recovery and are usually unaware of having been ill. We test for antibodies and a positive test indicates that the individual has had CMV infection and may still be carrying the virus. Having antibodies to CMV is of no significance to the health of the donor.

For those patients with a poor immune system, (bone marrow recipients or small babies) the presence of CMV in the blood given to them can cause a life-threatening illness. However, CMV positive blood is safe to give to other patients not at risk, so donors are not informed of a positive result.

Skin-Piercing
Until recently if you had had skinpiercing of any kind, you had to wait 12 months before giving blood. We have now introduced an extra supplementary test that means that we can now take donations 6 months after skin-piercing.

The test looks for evidence of past hepatitis B infection. Donors with positive test results will probably have to stop donating. If you fall into this group we will give you more detailed specific advice depending on your individual results.

False Reactions
All laboratory tests can produce 'false alarms', the technical term for this is a 'false reaction'. This is a positive result (usually a weak reaction) in the screening test, which, on confirmatory testing is shown to be negative. False reactions are a recognized complication of all biological tests and are perfectly normal. They are of no significance for the health of the donor.

Hemoglobin and Iron

To help keep up your hemoglobin levels, please read the following information:

Your Hemoglobin check

Every time you come to give blood or platelets your hemoglobin levels are checked. Hemoglobin, or 'Hb', is a protein found in the red blood cells that carries oxygen around your body and gives blood its red color.

Hemoglobin levels vary from one person to another. Men usually have higher levels than women. We want to be sure that your hemoglobin will not drop below normal after you have donated; if you donate platelets you lose a certain number of red cells each time, and after a number of donations your iron stores and Hb can drop.

Why might Hemoglobin levels be too low to Donate?

  • Variation between people - some of us just normally have a low level of hemoglobin.
  • Iron - we all need iron to make hemoglobin. If your iron stores are low, the hemoglobin may fall below normal (or below the donation level).

More About Iron.

Iron is very important because it helps your body produce hemoglobin. You give away a lot of iron when you donate blood, and so it is even more important for blood donors to eat plenty of iron-containing foods.

Where does Iron come from?

As iron is found in a variety of foods, you can usually get enough from a balanced diet. The major sources of iron are meat and meat-based foods; cereals and cereal products and vegetables.

What can I do to boost my Iron levels?

Iron is not easily absorbed by the body so we all need a regular supply of it. Try to eat a well-balanced diet. Also, every day try to eat three portions of food that are good sources of iron. Reducing the amount of snacks and sugary foods which contain very little iron will also help. These foods are good sources of iron:

  • Lean red meat, turkey and chicken.
  • Fish
  • Eggs.
  • Breakfast cereals - some cereals are fortified with iron.
  • Pulses and beans - in particular canned baked beans, chickpeas and lentils.
  • Nuts (including peanut butter).
  • Brown rice.
  • Bread - especially whole meal or brown breads.
  • Leafy green vegetables - especially curly kale, watercress, broccoli and spinach
  • Dried fruit - in particular apricots, raisins and prunes

The amount of animal fat in your diet should be kept low. So when eating meat, try to choose lean meat. It is also best to grill steam, roast or microwave food rather than fry it.

Vitamin C

Vitamin C (sometimes called ascorbic acid) helps you to absorb more iron. So to get the most from the food you eat, have vitamin C rich foods with meals: for example fresh fruits and vegetables or drinks such as fresh orange juice.

A note about tea! Tea may reduce the absorption of iron from foods. Avoid drinking tea just before, after or with meals.

What if I am a Vegetarian or Vegan?

Although iron from non-meat sources is more difficult for the body to absorb, people following a well balanced diet should be able to get enough iron in their diet.

Do I need to take Iron tablets?

Most people should be able to get all the iron they need by eating a varied and balanced diet and should not need to take iron supplements or tablets. Iron tablets should only be taken if your doctor has advised you to take them.