What Tests Do Kidney Donors Have to Take Before Transplant?
If you are interested in becoming a living kidney donor, you will need to undergo several tests before you are approved for donation surgery.
Some tests are to determine if you are healthy enough to become a donor, and some are to see whether your kidney is a good match for the person you want your kidney to go to. You’ll also meet with a number of specialists to make sure you’re fully informed about the process and have all the resources you need.
Initial Donor Testing
Once you have registered with the National Kidney Registry as a kidney donor and completed your medical history, you will need to complete your pre-workup labs, which includes blood tests and urine tests. Blood tests determine your overall health, especially the health of your kidneys and liver. Urine tests check the health of your kidneys.
Blood tests may include:
- Complete metabolic panel, which measures 14 different substances in your blood and shows how well the kidneys are functioning
- Liver function panel, which checks for injury, infection or disease in the liver
- Lipid panel, which measures your cholesterol levels and risk of cardiovascular disease
- Hemoglobin A1c, which measures blood sugar levels
- Complete blood count, which measures your overall health and detects disorders including anemia, infection and leukemia
- PT/PTT/INR (partial thromboplastin/partial thromboplastin time/international normalized ratio), which measures blood clotting
- Testing for viruses including HIV, syphilis, CMV, EBV, West Nile virus, tuberculosis, and hepatitis
To complete these tests, your transplant center may send you a testing kit in the mail. If so, you will need to take your testing kit to a phlebotomist to have your blood drawn. The phlebotomist will follow the detailed directions provided in the kit and will make all the blood draws required, as well as pack up the kit and mail it back for processing. If your transplant center does not offer mailed testing kits, you will do your pre-workup labs at your transplant center.
Kidney Matching Tests
If you want to donate to someone specific, you will need to undergo testing to determine if you are a good kidney match for your intended recipient. A “match” between a living kidney donor and a potential transplant recipient refers to the biological compatibility between the two people. There are three types of tests to determine compatibility.
Blood Type Testing
There are four basic blood types—O, A, B and AB—and the blood types of the donor and recipient must be compatible in order for a transplant to be successful.
| Donors with blood type: | Are blood type compatible with recipients with blood type: |
|---|---|
| O | O, A, B or AB |
| A | A or AB |
| B | B or AB |
| AB | AB |
Tissue Typing
Tissue typing, which is also called HLA (human leukocyte antigen) typing or antigen typing, is based on comparing six antigens, with a match score from zero out of six (a perfect match, which usually occurs only between certain siblings is a six out of six). The NKR also uses a more advanced matching process involving eplet mismatch analysis, which has proven to be a more precise measurement of a donor-recipient match compared to antigen matching.
Crossmatching
Crossmatching is a test designed to identify whether the intended recipient is “sensitized,” which means they have antibodies that will attack foreign tissue—the donated kidney—potentially causing the body to reject the transplant.
With the crossmatch test, blood samples from the potential donor and intended recipient are mixed to see how the recipient’s antibodies react with those of the potential donor. If the recipient’s antibodies attack the donor’s, the test is positive, which means the two have failed the crossmatch test and are not compatible. If the recipient’s antibodies do not react to the donor’s, the test is negative and the donor-recipient pair has passed the crossmatch test.
If you are an altruistic or Good Samaritan donor without a specific intended recipient for your donation, your transplant center will do a full genetic profile, which is entered into the NKR system. Once a recipient has been identified, then a crossmatch test is performed.
Additional Tests
In addition to the initial blood tests, several other tests will be required, including:
- Urinalysis to check for microalbumin/creatinine ratio
- 24-hour urine collection for creatinine clearance, total protein and microalbumin
- EKG to make sure your heart is in good condition, possibly followed by an echocardiogram, stress test and 24-hour blood pressure monitor
- Chest X-ray to look for lung or heart problems
- CT scan or MRI of your kidneys to ensure both kidneys are normal and healthy
- Renal scan if your kidneys are not the same size
- Pregnancy test for women of childbearing age
- PSA (prostate-specific antigen) test for men over 50
All required additional tests are done in-house at the transplant center, which also covers all the costs of the testing. Based on your evaluation, additional bloodwork and testing may be deemed necessary.
Required Wellness Tests
Most pre-donation testing will be conducted by the centers, but there are a few tests and procedures you will need to take care of on your own before you can be approved as a donor.
All women will need to have an updated Pap smear according to the current guidelines, and women over 45 should have a current mammogram. Men and women over 50 need to have a colonoscopy. All three of these procedures are considered preventative and are therefore 100% covered by most medical insurance policies. You may schedule these at your convenience with your own doctor, either before you apply to become a donor or once you are already registered.
Every center handles testing differently, and there are variations including which tests are required and how the testing is done. Your living donor coordinator will explain which tests are needed in your specific case, and answer any questions you have about the testing and evaluation process.
In addition to your living donor coordinator, you will also meet with several medical professionals and experts who will explain various aspects of your donation experience and will be able to answer questions and address concerns. These professionals include a transplant nephrologist, surgeon, donor advocate, donor social worker, pharmacist, nutritionist and financial coordinator.
Testing time also varies widely between centers. Some centers, such as Donor Care Network Centers of Excellence, commit to performing all workup testing in one day to avoid the inconvenience of making multiple trips to a transplant center. Other centers space testing out over weeks or months. Please check with your center to determine their specific testing protocol.