The light chain is also called the “Bence Jones protein,” named for the doctor Henry Bence Jones who studied its characteristics. Unattached, “free” light chains enter the blood and are excreted rapidly in the urine. In many myeloma patients, the coordinated process of making and attaching light chains and heavy chains fails in the malignant plasma cells. When the whole immunoglobulin is present in the urine, it is usually at a low level. Thus, it is most often present in the blood but not in the urine. This whole (intact) immunoglobulin, made of the four chains, is usually too large to pass through the kidney. There are two types of light chains, referred to as “kappa (k)” and “lambda (λ).” Some of these patients can be followed with a newer blood test that measures serum free light chains, which are a small fragment of the larger intact M protein.Īn intact immunoglobulin (Ig) molecule is composed of two larger pieces (heavy chains) and two smaller pieces (light chains) that are attached to each other. There are five types of heavy chains, and each type is represented by a specific letter: IgG, IgA, IgD, IgE and IgM. Monoclonal protein (M protein) levels can be measured in blood and/or urine samples, and these levels generally correlate with the extent of the myeloma.Ī small number of patients with myeloma have either “oligosecretory disease,” in which the detectable level of monoclonal protein is low, or “nonsecretory disease,” in which no monoclonal protein can be detected. In myeloma, large amounts of a single antibody are noted as a “monoclonal immunoglobulin spike” or “monoclonal spike” (M spike), indicating that the protein came from cells that originally started as single, malignant cell. In healthy individuals, plasma cells produce proteins called “polyclonal immunoglobulins.” These are a collection of antibodies that protect the body against all kinds of different invading viruses, bacteria or other infectious agents (antigens). Monoclonal Immunoglobulins (M Protein) and Light Chains (Bence Jones Protein) One or more focal lesions found on MRI studies (at least 5 mm in size).Ratio of involved/uninvolved serum free light chain ratio ≥ 100 (involved free light chain levels must be ≥ 100 mg/L).Clonal plasma cells in the bone marrow ≥ 60% with or without CRAB.Bone lesions-one or more osteolytic lesions found on x-ray, CT or PET‑CT scans.Anemia-hemoglobin concentration of > 2 g/dL below the lower limit of normal, or a hemoglobin concentration of Renal dysfunction-creatinine clearance 177 μmol/L (> 2 mg/dL).Calcium elevation-serum calcium > 0.25 mmol/L (> 1mg/dL) higher than the upper limit of normal or > 2.75 mmol/L (> 11 mg/dL).Evidence of end-organ damage that can be attributed to the disease: (CRAB criteria).Any one or more of the following myeloma-defining events:.Malignant plasma cells in the bone marrow ≥ 10% or presence of bony or extramedullary plasmacytoma, confirmed by biopsy.Revised International Myeloma Working Group (IMWG) Criteria for the Diagnosis of Multiple Myelomaīoth of the following criteria must be met: If there are not CRAB signs and/or symptoms, 60% plasma cells in the bone marrow indicates a diagnosis.Evidence of end-organ damage as defined by the CRAB criteria.Monoclonal proteins can be either intact monoclonal immunoglobulins or immunoglobulin light chains (Bence Jones proteins) found in the blood and/or urine.Unusually large amounts of monoclonal protein (called an “M spike”).Malignant plasma cells: Plasma cell level of >10% in a bone marrow biopsy sample.The diagnosis of myeloma depends on three main findings: A bone marrow biopsy to remove a small amount of bone filled with marrow.A bone marrow aspiration to remove a liquid marrow sample.Bone marrow testing involves two steps usually done at the same time in a doctor's office or a hospital: These include an elevated protein level, anemia and abnormalities in kidney function or calcium levels.īone Marrow Tests. Your doctor tests your bone marrow to look for malignant plasma cells. The results of blood tests that accompany periodic medical examinations may indicate the need for further evaluation for myeloma. Obtaining a precise diagnosis will help the doctor to: The Trish Greene Back to School ProgramĪn accurate diagnosis is one of the most important aspects of a person’s medical care.
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