It is also higher in individuals with IgA paraprotein compared to individuals with IgG paraprotein. The paraprotein can be an intact immunoglobulin, only light chains (light-chain myeloma, light-chain deposition disease, or amyloid light-chain amyloidosis), or rarely found only as heavy chains (heavy-chain disease).
Paraproteins can be detected in the serum and can also be excreted into the urine. Sometimes, if the paraprotein is only light chain (light-chain disease), then this is detected in the urine alone and not in the serum. The serum may paradoxically exhibit only hypogammaglobulinemia. It is important to note that the presence of paraprotein in serum, urine, or both indicates monoclonal gammopathy and not necessarily the presence of multiple myeloma in a patient. Multiple myeloma is one of the causes of monoclonal gammopathy.