Immunodeficiency with increased immunoglobulin M [IgM]

This code represents a primary immunodeficiency disorder characterized by abnormally high levels of immunoglobulin M (IgM) and typically low or absent levels of other immunoglobulin classes (IgG, IgA). This dysregulation results from a defect in B-cell class switching, leading to recurrent bacterial infections, opportunistic infections, and autoimmune manifestations.

Use this code when documentation clearly indicates a diagnosis of Hyper-IgM syndrome, a genetic disorder affecting immune function. This diagnosis is typically supported by laboratory findings showing elevated serum IgM and decreased or absent IgG and IgA, along with a history of recurrent infections.

• Ensure the documentation explicitly states "Hyper-IgM syndrome" or "immunodeficiency with increased IgM."
• Do not confuse this with transient hyper-IgM in infants or other secondary causes of elevated IgM without a primary immunodeficiency.
• Code any associated infections or manifestations separately as secondary diagnoses.