2026 ICD-10-CM Diagnosis Code D81.31Severe combined immunodeficiency due to adenosine deaminase deficiency

ICD-10-CM Codes›D50–D89›D80-D89›D81

ICD-10-CM D81.31
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

D81.31 is a billable ICD-10-CM diagnosis code for severe combined immunodeficiency due to adenosine deaminase deficiency. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). Coders also document this condition as SCID due to absent adenosine deaminase. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Immunity disorders and Other specified and unspecified nutritional and metabolic disorders.

Code Identity

ICD-10-CM Code
D81.31
Billable Status
Yes — Valid for Submission
Code Describes
Severe combined immunodeficiency due to adenosine deaminase deficiency
Short Description
Severe combined immunodef due to adenosine deaminase defic
Parent Code
D81.3
Adenosine deaminase [ADA] deficiency

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
CategoryD81Combined immunodeficiencies
This CodeD81.31Severe combined immunodeficiency due to adenosine deaminase deficiency

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • SCID due to absent adenosine deaminase
  • SCID due to absent lymphoid stem cells

Tabular List NotesGuidance

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

Inclusion Terms

  • ADA deficiency with SCID
  • Adenosine deaminase ADA deficiency with severe combined immunodeficiency

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.

    • Deficiency, deficient
      • adenosine deaminase (ADA)
        • with severe combined immunodeficiency (SCID)
    • Immunodeficiency
      • severe combined (SCID)
        • due to adenosine deaminase deficiency

Clinical ClassificationClinical

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

CCSR BLD008
Immunity disorders
Default principal diagnosis: inpatient Yes · outpatient Yes
CCSR END016
Other specified and unspecified nutritional and metabolic disorders
Default principal diagnosis: inpatient No · outpatient No

Patient EducationClinical

Immune System and Disorders

Your immune system is a complex network of cells, tissues, and organs. Together they help the body fight infections and other diseases.

The full article covers:

  • What is the immune system?
  • What are the parts of the immune system?
  • How does the immune system work?
  • What are the types of immunity?
  • What can go wrong with the immune system?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Code History & ChangesHistory

Replacement D81.31 replaces the following previously assigned code(s):

  • D81.3 - Adenosine deaminase [ADA] deficiency
FY 2020AddedAdded to the ICD-10-CM code setEffective October 1, 2019.
FY 2021–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About D81.31Overview

Is D81.31 (Adenosine deaminase [ADA] deficiency) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report severe combined immunodeficiency due to adenosine deaminase deficiency on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

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.