D89.839 ICD-10-CM Code: Cytokine release syndrome, grade unspecified
HCC Buddy Code Card
Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.
FY 2026 Apr update / Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism (D50-D89) / Certain disorders involving the immune mechanism (D80-D89)
D89.839
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceCytokine release syndrome, grade unspecified
A cytokine release syndrome reaction has occurred, but the severity grade (1-5) has not been specified in the medical documentation.
CMS-HCC V28
N/A—
Not mapped
CMS-HCC V24
N/A—
Not mapped
ACA/HHS
N/A—
Not mapped
ESRD/PACE
N/A—
Not mapped
RXHCC
N/A—
Not mapped
Code Book Path
Inclusion Terms
OfficialICD-10-CM does not list inclusion terms for D89.839 in this effective period.
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for D89.839 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for D89.839 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for D89.839 in this effective period.
Code First
Official- underlying cause, such as:
- complications following infusion, transfusion and therapeutic injection (T80.89-)
- complications of transplanted organs and tissue (T86.-)
Use Additional
Official- code for adverse effect, if applicable, to identify immune checkpoint inhibitors and immunostimulant drugs (T45.AX5)
Code Also
OfficialICD-10-CM does not list Code Also instructions for D89.839 in this effective period.
Buddy Documentation Tip
Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.
Is D89.839 an HCC code?
No. D89.839 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.
- Code
- D89.839
- Description
- Cytokine release syndrome, grade unspecified
- HCC (V28)
- No CMS-HCC V28 mapping
- RAF
- —
- Billable
- Yes
- Payment year
- 2026
Coder workflow notes
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This code does not map to an HCC category in any model (V28, V24, ESRD, RxHCC).
What This Code Means
D89.839 is the ICD-10-CM diagnosis code for cytokine release syndrome, grade unspecified. A cytokine release syndrome reaction has occurred, but the severity grade (1-5) has not been specified in the medical documentation. D89.839 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).
D89.839 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.
Query the provider to determine the appropriate grade based on clinical presentation and symptoms.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for D89.839 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Query the provider to determine the appropriate grade based on clinical presentation and symptoms
- •This code should be temporary; assign a specific grade code once clinical severity is determined