IgD is mainly found on the surface of B cells and may help regulate B-cell function. IgD likely serves as an early B-cell antigen receptor; however, the function of the circulating IgD is largely unknown. IgD functions to activate some lymphocytes.
Normal value: ≤15.3 mg/dL.
Use
Diagnosis of rare IgD myelomas (greatly increased)
Interpretation
Increased In
Monoclonal
IgD multiple myeloma
MGUS
Polyclonal
Chronic infection (moderately)
Autoimmune disease
Acute viral hepatitis
COPD
After allogeneic bone marrow transplantation
Decreased In
Hereditary deficiencies
Acquired immunodeficiency
Non-IgD myeloma
Infancy, early childhood
Limitations
An elevated IgD need to be identified as monoclonal or polyclonal by immunofixation method.