2026 ICD-10-CM Diagnosis Code D89.44Hereditary alpha tryptasemia

ICD-10-CM Codes›D50–D89›D80-D89›D89

ICD-10-CM D89.44
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

D89.44 is a billable ICD-10-CM diagnosis code for hereditary alpha tryptasemia. 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. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Immunity disorders.

Code Identity

ICD-10-CM Code
D89.44
Billable Status
Yes — Valid for Submission
Code Describes
Hereditary alpha tryptasemia
Short Description
Hereditary alpha tryptasemia
Same as the full description in the CMS dataset.
Parent Code
D89.4
Mast cell activation syndrome and related disorders

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 CodeD89.44Hereditary alpha tryptasemia

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Use Additional Code

  • code, if applicable, for:
  • allergy status, other than to drugs and biological substances Z91.0
  • personal history of anaphylaxis Z87.892

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.

    • Hereditary alpha tryptasemia(syndrome)
    • Syndrome
      • hereditary alpha tryptasemia
    • Tryptasemia, hereditary alpha

Clinical ClassificationClinical

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

CCSR BLD008
Immunity disorders
Default principal diagnosis: inpatient Yes · outpatient Yes

Code History & ChangesHistory

Replacement D89.44 replaces the following previously assigned code(s):

  • D89.49 - Other mast cell activation disorder
FY 2022AddedAdded to the ICD-10-CM code setEffective October 1, 2021.
FY 2023–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About D89.44Overview

Is D89.44 (Mast cell activation syndrome and related disorders) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report hereditary alpha tryptasemia on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does D89.44 group to?

When hereditary alpha tryptasemia is the principal diagnosis on an inpatient stay, it groups to MS-DRG 814, 815, 816, with relative weights from 0.6320 to 2.1267 depending on complications. Higher weights mean higher Medicare reimbursement.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.