What is ICD-10 code D80.4?

D80.4 is the ICD-10-CM diagnosis code for Selective deficiency of immunoglobulin M [IgM]. A condition where the body has abnormally low levels of IgM antibodies, an important early immune response protein. D80.4 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. D80.4 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. D80.4 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. D80.4 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.

Which HCC does D80.4 map to under V28?

D80.4 maps to CMS-HCC V28 HCC 115 (Specified Immunodeficiencies and White Blood Cell Disorders). The category numbers, labels, and conditions come from the CMS-HCC V28 model file for payment year 2026.

2026 ICD-10-CM D80.4: Selective deficiency

D80.4 maps to CMS-HCC V28 115. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · HCC Buddy coding tools

ICD-10-CM Code View

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Code lookupD80.4

Effective 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)

D80.4

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

Selective deficiency of immunoglobulin M [IgM]

A condition where the body has abnormally low levels of IgM antibodies, an important early immune response protein.

Buddy Insight

Selective immunoglobulin M deficiency is a rare primary immunodeficiency characterized by isolated low Immunoglobulin M levels with normal Immunoglobulin G and Immunoglobulin A.

Overview Risk Models Code Book Documentation Audit Notes Edition comparison

CMS-HCC V28

Mapped

HCC 115

Specified Immunodeficiencies ...

Code-level coefficient reference

CMS-HCC V24

Historical

Not used for standard CY2026 Medicare Advantage payment. Select a historical period to review V24.

Not used for CY2026 payment

ACA/HHS

Mapped

HCC 074

HHS-HCC 074 adult, RAF varies...

Code-level coefficient reference

ESRD/PACE

Mapped

HCC 47

Disorders of Immunity

Code-level coefficient reference

RXHCC

Mapped

HCC 99

Immune Disorders

Code-level coefficient reference

Code Book Path

Official

D80Immunodeficiency with predominantly antibody defects D80.4Selective deficiency of immunoglobulin M [IgM]

Inclusion Terms

Official

No inclusion terms are included in this display for D80.4. Check the code and parent instructions in the Code Book.

Excludes 2

Official

autoimmune disease (systemic) NOS (M35.9)Inherited from D50-D89
certain conditions originating in the perinatal period (P00-P96)Inherited from D50-D89
complications of pregnancy, childbirth and the puerperium (O00-O9A)Inherited from D50-D89
congenital malformations, deformations and chromosomal abnormalities (Q00-Q99)Inherited from D50-D89
endocrine, nutritional and metabolic diseases (E00-E88)Inherited from D50-D89
human immunodeficiency virus [HIV] disease (B20)Inherited from D50-D89
injury, poisoning and certain other consequences of external causes (S00-T88)Inherited from D50-D89
neoplasms (C00-D49)Inherited from D50-D89
symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)Inherited from D50-D89

Related Codes

Official

D80.0Hereditary hypogammaglobulinemia D80.1Nonfamilial hypogammaglobulinemia D80.2Selective deficiency of immunoglobulin A [IgA]D80.3Selective deficiency of immunoglobulin G [IgG] subclasses D80.5Immunodeficiency with increased immunoglobulin M [IgM]

Includes

Official

defects in the complement systemInherited from D80-D89
immunodeficiency disorders, except human immunodeficiency virus [HIV] diseaseInherited from D80-D89
sarcoidosisInherited from D80-D89

Excludes 1

Official

autoimmune disease (systemic) NOS (M35.9)Inherited from D80-D89
functional disorders of polymorphonuclear neutrophils (D71-)Inherited from D80-D89
human immunodeficiency virus [HIV] disease (B20)Inherited from D80-D89

Code First

Official

No Code First sequencing instructions are included in this display for D80.4. Check the code and parent instructions in the Code Book.

Use Additional

Official

No Use Additional Code instructions are included in this display for D80.4. Check the code and parent instructions in the Code Book.

Code Also

Official

No Code Also instructions are included in this display for D80.4. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance

Documentation must include quantitative Immunoglobulin M levels demonstrating significant reduction below age-appropriate reference ranges, normal Immunoglobulin G and Immunoglobulin A levels to confirm selectivity, clinical manifestations including frequency and types of infections, and management plan.

Document any associated conditions such as autoimmune disease or malignancy that may cause secondary Immunoglobulin M deficiency.

MEAT Support

HCC Buddy guidance

Document any associated conditions such as autoimmune disease or malignancy that may cause secondary Immunoglobulin M deficiency.

Audit Caution

HCC Buddy guidance

Do not confuse with hyper-Immunoglobulin M syndrome (D80.5), which has elevated Immunoglobulin M with deficient class-switching.

Ensure Immunoglobulin M deficiency is not secondary to another condition (medications, lymphoproliferative disease) that should be coded as the primary diagnosis.

Low Immunoglobulin M alone without clinical significance may not warrant coding.

Common Mistakes

HCC Buddy guidance

D80.5 (immunodeficiency with increased Immunoglobulin M, which is the opposite pattern with elevated Immunoglobulin M and low other classes), D80.2 (selective Immunoglobulin A deficiency, different immunoglobulin class), D80.3 (selective Immunoglobulin G subclass deficiency), D80.9 (unspecified antibody deficiency when the specific class is not documented).

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is D80.4 an HCC code?

Yes. D80.4 (Selective deficiency of immunoglobulin M [IgM]) maps to HCC 115, Specified Immunodeficiencies and White Blood Cell Disorders under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.565. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.

Coder answer: D80.4 is billable and maps to V28 HCC 115, Specified Immunodeficiencies and White Blood Cell Disorders. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code: D80.4
Description: Selective deficiency of immunoglobulin M [IgM]
HCC (V28): HCC 115 — Specified Immunodeficiencies and White Blood Cell Disorders
RAF reference coefficient: 0.565
Billable: Yes
Payment year: 2026

HCC Category Mapping

V28HCC 115, Specified Immunodeficiencies and White Blood Cell Disorders

0.565

ESRDHCC 47, Disorders of Immunity

Not separately weighted

RxHCCHCC 99, Immune Disorders

Not separately weighted

These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. Weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.

Work D80.4 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT review for D80.4

For D80.4, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.

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

Coder workflow notes

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What This Code Means

D80.4 is the ICD-10-CM diagnosis code for selective deficiency of immunoglobulin m [igm]. A condition where the body has abnormally low levels of IgM antibodies, an important early immune response protein. D80.4 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, D80.4 maps to Specified Immunodeficiencies and White Blood Cell Disorders (HCC 115) with a source-labeled community, non-dual, aged reference coefficient of 0.565. No V24 mapping is shown for D80.4; use the applicable model and payment year when reviewing the V28 mapping. For CY2026 non-PACE Medicare Advantage, CMS uses 100% of the 2024 CMS-HCC model (V28). PACE uses a separate model blend. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.

IgM deficiency may increase susceptibility to certain infections, particularly encapsulated bacteria. For D80.4, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule. 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, source-labeled coefficient references, and MEAT documentation criteria for D80.4 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•IgM deficiency may increase susceptibility to certain infections, particularly encapsulated bacteria
•Document any associated infections or clinical complications

Clinical Significance

Selective immunoglobulin M deficiency is a rare primary immunodeficiency characterized by isolated low Immunoglobulin M levels with normal Immunoglobulin G and Immunoglobulin A. Since Immunoglobulin M is the first antibody produced during an initial immune response, deficiency increases vulnerability to bloodstream infections with encapsulated organisms such as Streptococcus pneumoniae and Neisseria meningitidis.

Documentation Requirements

✓Documentation must include quantitative Immunoglobulin M levels demonstrating significant reduction below age-appropriate reference ranges, normal Immunoglobulin G and Immunoglobulin A levels to confirm selectivity, clinical manifestations including frequency and types of infections, and management plan.
✓Document any associated conditions such as autoimmune disease or malignancy that may cause secondary Immunoglobulin M deficiency.

Commonly Confused Codes

•D80.5 (immunodeficiency with increased Immunoglobulin M, which is the opposite pattern with elevated Immunoglobulin M and low other classes), D80.2 (selective Immunoglobulin A deficiency, different immunoglobulin class), D80.3 (selective Immunoglobulin G subclass deficiency), D80.9 (unspecified antibody deficiency when the specific class is not documented).