What is ICD-10 code D80.5?

D80.5 is the ICD-10-CM diagnosis code for Immunodeficiency with increased immunoglobulin M [IgM]. A condition where the body has abnormally high levels of IgM antibodies combined with deficiency of other antibody types. D80.5 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. D80.5 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. D80.5 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. D80.5 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

What is the V28 vs V24 difference for D80.5?

CMS phased in the V28 risk adjustment model over payment years 2024 (33%), 2025 (67%), and 2026 (100%), replacing V24. V28 consolidates HCC categories, removes some lower-acuity conditions, and recalibrates RAF weights across the entire model. For D80.5, V28 maps to Disorders of Immunity, Neutropenia at RAF 0.369 while V24 mapped to Disorders of Immunity at RAF 0.472. Both models can still appear in legacy data and in payer-specific lookback periods.

What should coders know when reporting D80.5?

This represents a specific immunodeficiency pattern with elevated IgM; document other deficient immunoglobulins Note any associated infections, autoimmune features, or lymphoid hyperplasia Because D80.5 maps to a payment HCC, the documentation must also satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's risk adjustment score.

D80.5 ICD-10 Code: Immunodeficiency with increased

ICD-10-CM Code View

HCC Buddy Code Card

Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.

Code lookupD80.5Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism (D50-D89) / Certain disorders involving the immune mechanism (D80-D89)

D80.5

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Immunodeficiency with increased immunoglobulin M [IgM]

A condition where the body has abnormally high levels of IgM antibodies combined with deficiency of other antibody types.

Buddy Insight

CMS-HCC V28

Mapped

HCC 115

Disorders of Immunity, Neutro...

RAF 0.369

CMS-HCC V24

Mapped

HCC 47

Disorders of Immunity

RAF 0.472

ACA/HHS

Not risk-adjusted for this model/period.

RAF 0

ESRD/PACE

Mapped

HCC 47

Disorders of Immunity

RAF 0.0

RXHCC

Mapped

HCC 99

Immunodeficiencies

RAF 0.0

Code Trumping

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Code Book Path

Official

D80Immunodeficiency with predominantly antibody defects

D80.5Immunodeficiency with increased immunoglobulin M [IgM]

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for D80.5 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for D80.5 in this effective period.

Related Child Codes

Official

D80.0Hereditary hypogammaglobulinemia

D80.1Nonfamilial hypogammaglobulinemia

D80.2Selective deficiency of immunoglobulin A [IgA]

D80.3Selective deficiency of immunoglobulin G [IgG] subclasses

D80.4Selective deficiency of immunoglobulin M [IgM]

Includes

Official

ICD-10-CM does not list Includes notes for D80.5 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for D80.5 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for D80.5 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for D80.5 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for D80.5 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Documentation must include quantitative immunoglobulin levels showing elevated Immunoglobulin M with reduced Immunoglobulin G and Immunoglobulin A, genetic testing results if available (CD40 ligand or activation-induced cytidine deaminase mutations), clinical manifestations including infection history, neutropenia if present, and treatment including immunoglobulin replacement therapy and prophylactic antimicrobials.

MEAT Support

HCC Buddy guidance

Audit Caution

HCC Buddy guidance

The hallmark of this condition is the inverse pattern: HIGH Immunoglobulin M with LOW Immunoglobulin G and Immunoglobulin A. Do not confuse with D80.4 (selective Immunoglobulin M deficiency) which has the opposite immunoglobulin profile. Elevated Immunoglobulin M can also occur in chronic infections and autoimmune diseases

ensure the elevation is due to a class-switching defect rather than reactive polyclonal Immunoglobulin M elevation.

Common Mistakes

HCC Buddy guidance

D80.4 (selective Immunoglobulin M deficiency which has LOW Immunoglobulin M, the opposite pattern), D80.0 (hereditary hypogammaglobulinemia which has all immunoglobulins low), D81.2 (severe combined immunodeficiency with B-cell numbers preserved but different mechanism), D83.0 (common variable immunodeficiency with B-cell abnormalities, a different entity).

Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.

Is D80.5 an HCC code?

Yes. D80.5 maps to Disorders of Immunity, Neutropenia under the CMS-HCC V28 risk adjustment model (and Disorders of Immunity under V24).

HCC Category Mapping

V28HCC 115, Disorders of Immunity, Neutropenia

0.369

V24HCC 47, Disorders of Immunity

0.472

ESRDHCC 47, Disorders of Immunity

0.000

RxHCCHCC 99, Immunodeficiencies

0.000

RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.

MEAT Criteria for D80.5

For D80.5to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically, it has to be re-documented and supported each calendar year.

MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
EEvaluate: test results, medication response, or physical findings reviewed by the provider
AAssess: explicit mention in the assessment or plan with acknowledgment of status
TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis

Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed D80.5 during that encounter, not just copy-forwarded from a problem list.

What This Code Means

D80.5 is the ICD-10-CM diagnosis code for immunodeficiency with increased immunoglobulin m [igm]. A condition where the body has abnormally high levels of IgM antibodies combined with deficiency of other antibody types. D80.5 sits in the ICD-10-CM chapter for diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism (d50-d89), within the section covering certain disorders involving the immune mechanism (d80-d89).

Under the CMS-HCC V28 risk adjustment model, D80.5 maps to Disorders of Immunity, Neutropenia (HCC 115) with a community, non-dual, aged base RAF weight of 0.369. Under the older CMS-HCC V24 model, D80.5 maps to Disorders of Immunity (HCC 47) with a community, non-dual, aged base RAF weight of 0.472. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.

This represents a specific immunodeficiency pattern with elevated IgM; document other deficient immunoglobulins. Because D80.5 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.

HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for D80.5 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•This represents a specific immunodeficiency pattern with elevated IgM; document other deficient immunoglobulins
•Note any associated infections, autoimmune features, or lymphoid hyperplasia

Clinical Significance

Immunodeficiency with increased immunoglobulin M, also known as hyper-Immunoglobulin M syndrome, is a primary immunodeficiency caused by defective immunoglobulin class switching, resulting in elevated Immunoglobulin M but severely deficient Immunoglobulin G and Immunoglobulin A. Patients are highly susceptible to opportunistic infections including Pneumocystis jirovecii pneumonia, Cryptosporidium enteritis, and recurrent bacterial infections.

Documentation Requirements

✓Documentation must include quantitative immunoglobulin levels showing elevated Immunoglobulin M with reduced Immunoglobulin G and Immunoglobulin A, genetic testing results if available (CD40 ligand or activation-induced cytidine deaminase mutations), clinical manifestations including infection history, neutropenia if present, and treatment including immunoglobulin replacement therapy and prophylactic antimicrobials.

Commonly Confused Codes

•D80.4 (selective Immunoglobulin M deficiency which has LOW Immunoglobulin M, the opposite pattern), D80.0 (hereditary hypogammaglobulinemia which has all immunoglobulins low), D81.2 (severe combined immunodeficiency with B-cell numbers preserved but different mechanism), D83.0 (common variable immunodeficiency with B-cell abnormalities, a different entity).