ICD-10 Code D80.4 – Selective deficiency of immunoglobulin M [IgM] (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code D80.4 – Selective deficiency of immunoglobulin M [IgM]
What it is
D80.4 identifies a selective deficiency of immunoglobulin M, a primary antibody disorder. It means the patient has abnormally low IgM with other immunoglobulins not necessarily reduced.
Clinical signs
Clinical features vary; refer to documentation. Common findings include recurrent infections, especially sinopulmonary infections, and an immune workup showing isolated low IgM.
When to use this code
Use D80.4 when the provider documents selective IgM deficiency or a comparable diagnosis supported by immunology testing. It is appropriate for confirmed primary immunodeficiency cases, not for nonspecific infection complaints. If the record only notes abnormal labs without diagnosis, check documentation.
Do not use for
Do not use this code for transient low IgM, secondary hypogammaglobulinemia, or other defined antibody deficiencies. Check documentation if the low IgM is part of a broader immunodeficiency disorder.
Coding tip
Code D80.4 only when the chart clearly states selective IgM deficiency or equivalent wording.