Pathology/Lab Coding Alert

If you don't know "typing" from "crossmatch," you'll have a hard time picking the right code when your lab performs human leukocyte antigen (HLA) testing for transplant patients. Get a clear snapshot of the testing that leads to transplant by reading the following guidance:

The surface of almost every cell has protein molecules called human leukocyte antigens (HLA) that the body uses to distinguish itself from foreign invaders. Testing to identify these molecules (markers) is called "HLA typing."

"The most successful tissue transplants often occur when the donor and recipient have an increase of key HLA markers in common," explains Diana Voorhees, MA, CLS, MT (ASCP) SH, CLCP, principal with DV and Associates Inc. in Salt Lake City.

That's why the first step in searching for a transplant donor is HLA typing of the recipient and potential donor. Correlating the results of the donor/recipient tests is called "HLA matching." "Depending upon the results of low resolution or preliminary typing, labs will perform additional typing or high resolution testing," Voorhees says.

Read "Welcome 86825-82826 -- Serology Isn't the Only HLA Crossmatch" in this issue to see how you should choose between codes in the range 86812-86817 (HLA typing ...) or 83891-83912 (Molecular diagnostics ...) to report these tests.

You'll rarely see a "perfect match" of HLA antigens, but immunosuppressive medication can often help  overcome the variation for a successful transplant.That is, unless the recipient has too many previously formed antibodies to the donor's HLA. "Previous pregnancies, transplants, blood transfusions, or infections could be the source of these antibodies," Voorhees says.

If knowing the HLA type is not enough to predict a successful transplant, what else can lab tests reveal? Compatibility testing, called "crossmatch," will ferret outthe donor antigen/recipient antibody reactions that could be a transplant deal breaker.

Think of the crossmatch as a mini-transplant test. By mixing donor/recipient blood and monitoring cell death, the lab test can serve as a predictive tool for transplant success as follows:

• A positive crossmatch means that the recipient cells killed off donor blood -- not good.

• A negative crossmatch means that the recipient doesn't have antibodies against the donor's HLA -- that's good. See how to code these tests using 86805-86808 -- (Lymphocytotoxicity assay, visual crossmatch ...) and new codes 86825 and +86826 (Human leukocyte antigen [HLA] crossmatch, non-cytotoxic [e.g., using flow cytometry]) when you read "Welcome 86825-82826 -- Serology Isn't the Only HLA Crossmatch" in this issue.