Does Blood Type Matter for Kidney Transplant?
Blood type is an important factor in kidney transplantation. The blood types of the kidney donor and the transplant recipient must be compatible to prevent the recipient’s body from rejecting the donated kidney.
There are four main blood types: A, B, AB and O. Each blood type is characterized by the presence or absence of specific antigens on the surface of red blood cells. The name of a blood type indicates which antigens are present. These antigens can trigger an immune response if incompatible blood types are mixed.
All blood types can be either positive or negative, but while negative and positive matter in blood transfusions, they are not a factor in transplantation. The most common blood type is O (45% of the population has this blood type), followed by A (40%), B (11%) and AB (4%).
Of the kidney patients currently on the waitlist for a kidney from a deceased donor, 54% have blood type O, 27% have blood type A, 16% have blood type B and 3% have blood type AB.
Blood Compatibility for Donors
| Donors with blood type: | Can donate a kidney to recipients with blood type: |
|---|---|
| O | O, A, B or AB |
| A | A or AB |
| B | B or AB |
| AB | AB |
Blood Compatibility for Recipients
| Kidney patients with blood type: | Can receive a kidney from donors with blood type: |
|---|---|
| O | O |
| A | A or O |
| B | B or O |
| AB | A, B, AB or O |
There are two important things to know about blood type and kidney transplantation:
- Blood type is just the first step in determining compatibility between a kidney donor and a transplant recipient. The next factor that influences compatibility is a blood test for tissue typing. Tissue typing involves screening your blood for specific antigens (called Human Leukocyte Antigens) that are present on white blood cells that can react with another person’s blood. Tissue typing involves screening both the donor and the recipient’s blood individually. It’s fairly common for a donor and recipient to have compatible blood types but still be deemed incompatible for a kidney transplant. The closer the match of the HLA antigens, the better the outcomes are for kidney transplantation. This is because the recipient is less likely to develop antibodies against their donor’s HLA antigens. Fortunately, there is an easy way around this problem: the National Kidney Registry’s Voucher Program.
- If a donor and recipient are considered incompatible, the donor can still donate on behalf of the recipient. The National Kidney Registry’s Voucher Program allows incompatible donor-recipient pairs to enter the NKR’s large pool of donors to find the best possible match for both the donor and the recipient. When the donor donates, their kidney goes to a well-matched recipient and a voucher is generated for the donor’s intended recipient. When the recipient is ready for transplant, they redeem their voucher and are prioritized to receive the best possible match from a kidney donor in the NKR pool.
Because the NKR is able to find the best match for each recipient from among its donor pool, which is the largest in the world, there is no need for a donor to be a kidney transplant blood type match for the person they want to donate a kidney to. In fact, in most cases, even if a donor is a good match for their intended recipient, they can find an even better match by entering the Voucher Program