D89.40Billable
Mast cell activation, unspecified
- Chapter
- 3. Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism
- Category
- D89
- Effective date
- October 1, 2026
Related codes in category D89
D89Oth disorders involving the immune mechanism, NECD89.0Polyclonal hypergammaglobulinemiaYesD89.1CryoglobulinemiaYesD89.2Hypergammaglobulinemia, unspecifiedYesD89.3Immune reconstitution syndromeYesD89.4Mast cell activation syndrome and related disordersD89.41Monoclonal mast cell activation syndromeYesD89.42Idiopathic mast cell activation syndromeYesD89.43Secondary mast cell activationYesD89.44Hereditary alpha tryptasemiaYesD89.49Other mast cell activation disorderYesD89.8Oth disrd involving the immune mechanism, NEC
Frequently asked questions
What is ICD-10 code D89.40?
D89.40 is an ICD-10-CM diagnosis code for Mast cell activation, unspecified.
Is D89.40 a billable code?
Yes. D89.40 is billable and specific enough to be used on a claim.
What ICD-10-CM chapter is D89.40 in?
D89.40 falls under Chapter 3: Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism.
When did D89.40 become effective?
D89.40 has been effective since October 1, 2026, per the CMS/CDC ICD-10-CM annual release.
What other codes are related to D89.40?
D89.40 belongs to category D89, which includes 12 other codes — see the related codes list on this page.
ICD-10-CM data maintained by CDC/CMS (public domain). Always verify codes with authoritative sources before making coding or billing decisions.