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Health Information and Tools > Kidney Transplant > Living Kidney Donation > Testing >  Blood Pressure, Blood Typing, and Blood Tests
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Living Kidney Donation

First stage of testing for donation

Blood pressure testing

You will be asked to have at least 3 blood pressure readings done by a medical professional.

You may also be asked to do 24 hour blood pressure monitoring. This test makes sure that you don’t have high blood pressure, which can damage the kidneys. During the test, you’ll wear a blood pressure cuff all day while you do your usual activities. As part of the test, you’ll have to write down what you do during the 24 hours.

Blood typing

Knowing your blood type (group) is an important early step to match a donor and recipient.

What blood groups can be matched (are compatible)?

There are 4 different blood types: O, A, B, and AB. If the donor and recipient have different blood types, living donation may not be possible for this person. The recipient’s blood type could have antibodies against the donor’s blood type. This will make the recipient’s body reject the kidney. You may want to look at the Kidney Paired Donation as an option.

Another way to group blood type is by the Rh factor. If you have this marker (antigen) you’re Rh positive (+), if you don’t, you’re Rh negative (-). Unlike with blood donation and transfusions, the Rh factor doesn’t have to be the same for you to donate a kidney.

This table shows the donor and recipient blood types that can be matched:

Donor’s blood type Recipient’s blood type
O O, A, B, or AB
A A or AB
B B or AB
AB AB

Tissue typing

This is a blood test that looks for antigens called human leukocyte antigens (HLA). Your blood is tested to see if your genetic make-up is close to the recipient’s. A person gets genes from both their mother and father. Blood relatives like parents and siblings may have a similar genetic make-up. The lab looks at the HLA antigens and tries to see how close the match is between you and the recipient. This doesn’t need to be a perfect match, but it’s better to have a good match for a more successful outcome.

An antigen is a small substance like a protein or molecule that makes the body form antibodies against it. An antigen causes an immune response in the body.

Crossmatch

​​​The crossmatch checks if the recipient’s immune system may react to your donated kidney. Recipient and donor blood is tested to see if there would be a reaction.

A negative crossmatch means there’s no reaction between your blood and the recipient’s blood. This means they are compatible and there’s a lower chance the kidney will be rejected.​​​

In most cases, a positive crossmatch means that your blood and the recipient’s blood don’t match or are not compatible, and your kidney is likely to be rejected by the recipient.​​​

​​​This blood test is done during your evaluation and again within 1 month of your surgery to make sure that the result hasn’t changed.

​​​If you and your recipient are not compatible but you still want to donate your kidney, you might consider the Kidney Paired Donation (KPD) Program. The donor evaluation stays the same.​

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