ICD-10 Code D89.835 – Cytokine release syndrome, grade 5 (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code D89.835 – Cytokine release syndrome, grade 5
What it is
D89.835 identifies the most severe form of cytokine release syndrome, a systemic inflammatory reaction that can follow certain immune therapies. It indicates a grade 5 event, meaning the condition is fatal.
Clinical signs
Clinical features vary; refer to documentation. Grade 5 implies death attributable to cytokine release syndrome, usually after a documented severe inflammatory response.
When to use this code
Use this code when the record clearly states cytokine release syndrome, grade 5, or documents death due to this condition. You should code it only when the provider links the fatal outcome to cytokine release syndrome. Check documentation for the triggering therapy and clinical attribution if needed.
Do not use for
Do not use this code for nonfatal cytokine release syndrome, lower grades, or nonspecific inflammatory reactions. If the chart does not confirm grade 5 or fatality, check documentation.
Coding tip
Always verify that the provider explicitly documents grade 5 and the causal relationship before assigning D89.835.