ICD-10 Code D80.5 – Immunodeficiency with increased immunoglobulin M [IgM] (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code D80.5 – Immunodeficiency with increased immunoglobulin M [IgM]
What it is
D80.5 identifies an inherited or acquired immunodeficiency pattern associated with elevated IgM and impaired normal antibody function. Use it when documentation specifically states increased immunoglobulin M [IgM] with immune deficiency.
Clinical signs
Clinical features vary; refer to documentation. Patients may have recurrent infections, especially bacterial infections, and evidence of abnormal humoral immunity. Support the code with provider-documented immunodeficiency and increased IgM.
When to use this code
Use D80.5 when the record clearly documents immunodeficiency with increased IgM, including a named syndrome or disorder matching that description. You may code it when the provider links recurrent infections or immune dysfunction to this specific diagnosis. If the chart only notes abnormal immunoglobulin results without a diagnosis, check documentation.
Do not use for
Do not use this code for isolated elevated IgM without immunodeficiency, or for other antibody deficiencies. Check documentation if the condition is better described by another immune disorder.
Coding tip
Confirm the provider states both immunodeficiency and increased IgM before assigning D80.5.