Cytokine release syndrome, grade 4

This code signifies a severe, life-threatening systemic inflammatory response characterized by widespread cytokine activation, leading to significant organ dysfunction. It is a common and serious complication of immunotherapies, particularly CAR T-cell therapy, but can also occur with other treatments or conditions.

Apply this code when documentation explicitly states "cytokine release syndrome, grade 4" or provides clinical indicators consistent with a severe, life-threatening presentation requiring intensive care, such as mechanical ventilation, vasopressor support, or multi-organ failure. This grade is typically determined using established grading scales (e.g., ASTCT, CTCAE).

• Ensure the medical record clearly specifies "grade 4" CRS; do not assume the grade based on treatment or severity alone.
• Code any associated organ failures or complications separately, as they are not inherent to the CRS code itself.
• Consider sequencing this code as a principal diagnosis if it is the primary reason for admission or encounter, especially in the context of immunotherapy complications.