ICD-10 Code D89.831 – Cytokine release syndrome, grade 1 (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code D89.831 – Cytokine release syndrome, grade 1
What it is
D89.831 identifies a mild, grade 1 cytokine release syndrome. Use it when documentation states CRS grade 1, usually reflecting a low-severity inflammatory reaction after immune therapy.
Clinical signs
Clinical features vary; refer to documentation. Grade 1 CRS is generally described as mild and without severe organ dysfunction, hypotension, or hypoxia.
When to use this code
Use this code when the provider documents cytokine release syndrome and specifies grade 1. It is appropriate for encounters tied to CAR-T or other immunotherapy-related CRS when the grade is clearly recorded.
If the note only says “cytokine release syndrome” without a grade, check the record before assigning D89.831. You should code the documented severity, not assume it from treatment or setting.
Do not use for
Do not use this code for higher-grade CRS or for unrelated fever, infection, or sepsis. Check documentation if the record does not clearly support grade 1 CRS.
Coding tip
Always look for the provider’s stated CRS grade; if grade 1 is not explicitly documented, query or verify before coding.