D89.40
✓ Billable
Mast cell activation, unspecified
ICD-10-CM · FY2026 · Diseases of the Blood and Blood-Forming Organs
Code
D89.40
System
ICD-10-CM
Billable
Yes — valid for submission
Effective
FY2026
Chapter
Diseases of the Blood and Blood-Forming Organs
Source
CMS / CDC NCHS
⚠ Verify before billing. Confirm against the current CMS/NCHS ICD-10-CM files and your payer's rules before claims submission.
Frequently asked questions
What is ICD-10 code D89.40?
ICD-10-CM code D89.40 represents Mast cell activation, unspecified. It is a billable diagnosis code in the Diseases of the Blood and Blood-Forming Organs chapter, effective October 1, 2025 – September 30, 2026.
Is D89.40 billable?
Yes. D89.40 is a valid billable ICD-10-CM code for insurance claims and clinical documentation.
What chapter is D89.40 in?
D89.40 belongs to the Diseases of the Blood and Blood-Forming Organs chapter (D50–D89) of ICD-10-CM.
Related codes in the D89 category
D89
Other disorders involving the immune mechanism, not elsewhere classified
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D89.0
Polyclonal hypergammaglobulinemia
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D89.1
Cryoglobulinemia
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D89.2
Hypergammaglobulinemia, unspecified
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D89.3
Immune reconstitution syndrome
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D89.4
Mast cell activation syndrome and related disorders
Non-billable
D89.8
Other specified disorders involving the immune mechanism, not elsewhere classified
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D89.9
Disorder involving the immune mechanism, unspecified
Billable
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