Oncology & Hematology Coding Alert

Question: What kind of support is needed to report D84.821? Do I need to see an immunosuppressant in the meds list? Does the provider need to tell me the drug?

AAPC Forum Participant

Answer: According to AHA ICD-10 Coding Clinic Vol 7, No. 4 (2020), ICD-10-CM introduced the following codes in 2020 for the following reasons:

• D84.821 (Immunodeficiency due to drugs) documents “immunodeficiency due to medications that interfere with the immune system,” such as “immunosuppressants, corticosteroids and chemotherapy.”
• D84.822 (Immunodeficiency due to external causes) documents “immunodeficiency caused by external factors such as exposure to radiation therapy or due to bone marrow transplant.”
• D84.81 (Immunodeficiency due to conditions classified elsewhere) documents “an immunocompromised state due to a specific medical condition such as HIV, AIDS, certain cancers and genetic disorders ….”

Following this logic, you can see that supporting documentation for D84.821 would be evidence of prescribed chemotherapy or immunosuppressants, while D84.822 would require evidence of the patient undergoing radiation therapy or having received a bone marrow transplant. And you would use D84.81 as a secondary code alongside a medically appropriate ICD-10-CM code for the underlying condition.

The Coding Clinic also goes on to say you can assign “multiple codes … to show immunodeficiency due to multiple causes (e.g., cancer and antineoplastic medication).”