2026 ICD-10-CM Diagnosis Code D89.839Cytokine release syndrome, grade unspecified

ICD-10-CM Codes›D50–D89›D80-D89›D89

ICD-10-CM D89.839
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

D89.839 is a billable ICD-10-CM diagnosis code for cytokine release syndrome, grade unspecified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 814 through 816. The code is not accepted as a principal diagnosis by the Medicare Code Editor. Coders also document this condition as acute intoxication. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Immunity disorders.

Code Identity

ICD-10-CM Code
D89.839
Billable Status
Yes — Valid for Submission
Code Describes
Cytokine release syndrome, grade unspecified
Short Description
Cytokine release syndrome, grade unspecified
Same as the full description in the CMS dataset.
Parent Code
D89.83
Cytokine release syndrome

Code Classification

ChapterD50–D89Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism
SectionD80-D89Certain disorders involving the immune mechanism
CategoryD89Other disorders involving the immune mechanism, not elsewhere classified
This CodeD89.839Cytokine release syndrome, grade unspecified

Code EditsBilling

Medicare Code Editor checks that affect claim validity for D89.839.

Unacceptable principal diagnosis
There are selected codes that describe a circumstance which influences an individual's health status but not a current illness or injury, or codes that are not specific manifestations but may be due to an underlying cause. These codes are considered unacceptable as a principal diagnosis.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acute intoxication
  • Cytokine release syndrome
  • Cytokine release syndrome due to chimeric antigen receptor T-cell immunotherapy
  • Immune system complication of procedure

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Syndrome
      • cytokine release

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR BLD008
Immunity disorders
Default principal diagnosis: inpatient No · outpatient Yes

Clinical InformationClinical

  • Cytokine Release Syndrome

    a severe immune reaction characterized by excessive release of cytokines. symptoms include dyspnea; fever; headache; hypotension; nausea; rash; tachycardia; hypoxia; hyperferritinemia, and multiple organ failure. it is associated with viral infections, sepsis; autoimmune diseases and a variety of factors used in immunotherapy.

Code History & ChangesHistory

Replacement D89.839 replaces the following previously assigned code(s):

  • D89.89 - Oth disrd involving the immune mechanism, NEC
FY 2021AddedAdded to the ICD-10-CM code setEffective October 1, 2020.
FY 2022–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About D89.839Overview

Is D89.839 (Cytokine release syndrome) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report cytokine release syndrome, grade unspecified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does D89.839 group to?

On inpatient claims, cytokine release syndrome, grade unspecified maps to MS-DRG 814, 815, 816, with relative weights from 0.6320 to 2.1267 depending on complications. Higher weights mean higher Medicare reimbursement.

Can D89.839 be a principal diagnosis?

No. The Medicare Code Editor rejects this code as a principal diagnosis because cytokine release syndrome, grade unspecified describes a circumstance that influences health status rather than a current illness. Report it as a secondary diagnosis.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.