Monoclonal gammopathy of undetermined significance (MGUS) is a disease which is characterized by the presence of a specific protein named monoclonal protein or M protein in the blood.1 M proteins are produced in the bone marrow by plasma cells. They rarely affect the health of a normal person. But there are few chances that the steady accumulation of M protein in the body can progress to the cancerous diseases like multiple myeloma, lymphoma and many more. The complications of MGUS depend on its type. So, the physician keeps a close watch on the levels of M protein in MGUS to observe the progress of the disease.


Complications Of MGUS Or Monoclonal Gammopathy Of Undetermined Significance

The complications of monoclonal gammopathy of undetermined significance depend on the type of MGUS present in the body. The disease is of benign nature, rarely complicate into cancerous diseases. It is only a 1% chance that MGUS progress to more serious condition (cancer state).


The types and complications related to them in monoclonal gammopathy of undetermined significance are-

Non-IgM MGUS- it is IgG, IgA or IgD monoclonal gammopathy of undetermined significance that is the most common type of MGUS.2 It can progress to multiple myeloma. Multiple myelomas are malignant cancers characterized by abnormal production of antibodies in the bone marrow; in this condition, abnormal antibodies namely monoclonal proteins overcrowding in the bone marrow that may replace the healthy cells of the bone marrow. These harmful antibodies may travel to different parts of the body and accumulate there leading to damages in that particular part. It may also cause damage to the kidney, bone, blood cells, etc. It may result in the accumulation of calcium with depletion of red blood cells in the body. High calcium deposition in the blood may represent symptoms like too much thirst, nausea, vomiting, indigestion, etc. Other symptoms include dizziness, fatigue or irritability, confusion, bone injuries or bone fractures and weight loss.


IgM MGUS- it is prevalent in only 15% of patients with monoclonal gammopathy of undetermined significance. It has the potential to turn into Waldenstrom macroglobulinemia. This cancerous disease is a type of non-Hodgkin Lymphoma characterized by abnormal accumulation of abnormal protein namely macroglobulin. These abnormal proteins accumulate in the bone marrow disturbing the integrity of the bone. It causes anemia in the body by destroying many healthy white blood cells. This leads to a risk of developing infections. Macroglobulin also lowers the count of platelets in the body that causes increased incidences of bleeding and bruising. This disease can also spread to the liver and spleen leading to their enlargement and pain in the abdomen. Its symptoms also include impaired vision and problems related to the nervous system.

Light Chain MGUS- this disease is a newly classified type of monoclonal gammopathy of undetermined significance in which paraproteins are released in urine leading to a condition named as Bence Jones proteinuria. This condition can proceed into more serious condition or cancerous condition such as lymphoma, light chain deposition disease or AL amyloidosis. Lymphoma is a cancerous disease of lymph nodes and the lymphatic system of the body. Its symptoms include coughing, shortness of breath, fever without infection, itching and many more.

Light Chain Deposition Disease is characterized by the building up of light chain b cells in the kidney leading kidney damage. Kidney normally reabsorbs the light chain of B cells for utilization in the body. But light chain deposition disease affects this recycling ability of the kidney and damages the kidney due to the accumulation of the light chain B cells.

AL Amyloidosis is a less severe type of cancerous disease than multiple myeloma. It is characterized by the buildup of amyloids in the bone marrow. It also accumulates in the heart and kidney leading to heart and kidney failure.


Monoclonal gammopathy of undetermined significance is a benign condition that may complicate into cancer in a few cases. These cancers are serious in nature that can cause serious illness. They include multiple myeloma, lymphoma, AL amyloidosis, light chain deposition disease, and Waldenstrom macroglobulinemia.


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Pramod Kerkar

Written, Edited or Reviewed By:


Pain Assist Inc.

Last Modified On: August 19, 2019

This article does not provide medical advice. See disclaimer


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