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Monoclonal Gammopathies

Monoclonal gammopathies are conditions in which abnormal proteins are found in the blood.

Illustration of blood components
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These proteins develop from a small number of plasma cells in the bone marrow.

Plasma cells make up just 1 percent of bone marrow cells. Their main function is to fight off infection.

The most common condition linked with these abnormal proteins is monoclonal gammopathy of undetermined significance (MGUS). It is not cancer. But people with MGUS have an increased risk of developing serious diseases of the bone marrow and blood.

Symptoms and diagnosis

MGUS typically causes no symptoms. In fact, monoclonal protein in the blood is often found by accident when doing other routine blood work. This is called an incidental finding.

After an incidental finding of abnormal proteins, more testing is needed. A screening of the blood and sometimes the urine is recommended. This is generally done with a lab procedure called electrophoresis. Depending on the results of those tests, more testing to look for a suspected or confirmed condition may be done. 

Most people who have abnormal proteins in their blood will never progress to a more serious condition. In some instances, however, these illnesses can develop:

  • Multiple myeloma

  • Non-Hodgkin lymphoma

  • Plasma cell leukemia

  • Primary amyloidosis

  • Solitary plasmacytoma

  • Waldenstrom's macroglobulinemia

Symptoms of monoclonal gammopathies differ among these conditions, but can include:

  • Anemia, or low red blood cells counts

  • Fatigue, or tiredness

  • Weakness

  • Pain in the bones or soft tissues

  • Tingling or numbness in the feet or the hands

  • Infection that keeps coming back

  • Increased bruising

  • Bleeding

  • Weight loss

  • Headache

  • Vision problems

  • Swelling

  • Mental changes

Risk factors and causes

The chance of developing MGUS increases with age, but it is not common.

The exact cause of MGUS is unknown. Infection, autoimmune conditions, and the environment have been considered as possible contributors to MGUS, but research so far has not found a clear connection. Experts do know that the abnormal proteins don't seem to occur as a result of any particular diet or from eating dietary proteins. There is no risk of monoclonal gammopathies in first-degree family members, so screening of siblings and children is not needed.

Prognosis and follow-up

Because MGUS is not harmful, it doesn't need to be treated. A diagnosis of MGUS in the absence of other symptoms usually does not warrant the need for more testing. But because MGUS may transition to a more serious condition, monitoring is necessary throughout your life in order to identify problems as early as possible. This usually includes regular physical exams and blood work.