D89.831
BillableCytokine release syndrome, grade 1
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is D89.831 an HCC code?
No. D89.831 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.
This code does not map to an HCC category in any model (V28, V24, ESRD, RxHCC).
What This Code Means
D89.831 is the ICD-10-CM diagnosis code for cytokine release syndrome, grade 1. A mild immune reaction where the body releases excessive amounts of signaling proteins (cytokines) in response to treatment, typically occurring after CAR-T cell therapy or similar immunotherapies. D89.831 sits in the ICD-10-CM chapter for diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism (d50-d89), within the section covering certain disorders involving the immune mechanism (d80-d89).
D89.831 is a billable ICD-10-CM code but does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.
Always document the triggering event (CAR-T therapy, monoclonal antibody, etc.) in the medical record.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for D89.831 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Always document the triggering event (CAR-T therapy, monoclonal antibody, etc.) in the medical record
- •Grade 1 represents the mildest form; ensure the grade assignment matches clinical documentation of symptoms