Pathology/Lab Coding Alert

Question: The lab I code for does HLA typing and compatibility testing. Could you please explain the different types of tests and what they’re for?

Illinois Subscriber

Answer: Labs perform testing for human leukocyte antigens (HLA) for clinical situations such as identifying a suitable transplant donor.

Most cells have surface proteins, called HLA, which help the body distinguish itself from foreign invading cells. For a transplant patient, receiving tissue that doesn’t look like a foreign invader from a donor is the key to avoiding transplant rejection.

The first test labs typically perform is HLA “typing” to characterize the antigens present on patient and donor cells.

The lab might carry this out using serology tests, such as the following:

• 86812 (HLA typing; A, B, or C (e.g., A10, B7, B27), single antigen)
• 86813 (... A, B, or C, multiple antigens)
• 86816 (... DR/DQ, single antigen)
• 86817 (... DR/DQ, multiple antigens)

Or the lab might use molecular methods for the HLA typing, which you would report with appropriate codes from the range 81370-81383 (HLA Class I [and/or] Class II typing …)

Match: If the transplant donor and recipient have similar results for key HLA antigens, they might be a match. But if the recipient has previously developed antibodies against donor antigens (through a prior pregnancy or blood transfusion, for instance), it could be a problem. To evaluate this hazard, labs may perform HLA antibody testing.

Ab: For HLA antibody testing, the lab may perform a serology test such as 86807 or 86808 (Serum screening for cytotoxic percent reactive antibody (PRA) …) or an immunology test from the range 86828-86835 (Antibody to human leukocyte antigens (HLA), solid phase assays (eg, microspheres or beads, ELISA, flow cytometry) …).

Compatibility: If a donor is still in the running after those tests, the final transplant hurdle is the compatibility test, or crossmatch. The lab may perform a cytotoxicity test, such as 86805-86806 (Lymphocytotoxicity assay, visual crossmatch …) or 86807-86808 (Serum screening for cytotoxic percent reactive antibody (PRA) …), which involves mixing donor and recipient blood and monitoring cell death. Or the lab may perform a method such as 86825 and +86826 (Human leukocyte antigen (HLA) crossmatch, non-cytotoxic (e.g., using flow cytometry) …).

For any case, you’ll need to be aware of the lab orders and test procedures in order to select the proper code(s).