2026 ICD-10-CM Diagnosis Code D84.0Lymphocyte function antigen-1 [LFA-1] defect
ICD-10-CM Codes›D50–D89›D80-D89›D84
- Billable — Valid for Submission
- Chronic Condition
D84.0 is a billable ICD-10-CM diagnosis code for lymphocyte function antigen-1 [LFA-1] defect. 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. Coders also document this condition as lymphocyte function antigen-1 defect. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Immunity disorders.
D84.0 no longer risk-adjusts for Medicare Advantage: it mapped to HCC 47 under the retired CMS-HCC V24 model through payment year 2025 but maps to no category in the live V28 model. It still risk-adjusts in the PACE (CMS-HCC V22) category 47, ESRD (V21) category 47, ESRD (V24) category 47, and RxHCC Part D (V08) category 99 for payment year 2026.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
D84.0 no longer risk-adjusts for Medicare Advantage: it maps to no payment category in the live CMS-HCC V28 model, although it still risk-adjusts in the other CMS models shown below.
Source: CMS Payment Year 2026 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Lymphocyte function antigen-1 defect
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
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.
Convert D84.0 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About D84.0Overview
What is the ICD-10 code for lymphocyte function antigen-1 [LFA-1] defect?
The ICD-10-CM code for lymphocyte function antigen-1 [LFA-1] defect is D84.0 (sometimes written as D840). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Is D84.0 (Other immunodeficiencies) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report lymphocyte function antigen-1 [LFA-1] defect on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does D84.0 group to?
When lymphocyte function antigen-1 [LFA-1] defect 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.
What is the ICD-9 equivalent of D84.0?
Under the General Equivalence Mappings, lymphocyte function antigen-1 [LFA-1] defect converts to ICD-9-CM 279.8 (immune mechanism dis NEC). The mapping is approximate, so confirm the match fits the documentation.
Does D84.0 risk-adjust for Medicare Advantage payment?
Not for Medicare Advantage. D84.0 mapped to HCC 47 in the retired CMS-HCC V24 model, which last determined payment in 2025, but it maps to no category in the live V28 model; see all codes that no longer risk-adjust. It still risk-adjusts in the PACE (CMS-HCC V22) category 47 (Disorders of Immunity), ESRD (V21) category 47 (Disorders of Immunity), ESRD (V24) category 47 (Disorders of Immunity), and RxHCC Part D (V08) category 99 (Immune Disorders).
