Health Encyclopedia

Monoclonal Gammopathies

What are monoclonal gammopathies?

Monoclonal gammopathies are conditions in which abnormal proteins are found in the blood. These proteins grow from a small number of plasma cells in the bone marrow. Plasma cells make up just a small number of bone marrow cells. Their main job 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 a greater risk of getting serious diseases of the bone marrow and blood. 

What causes monoclonal gammopathies?

The exact cause of MGUS is not known. Infection, immune system problems, and the environment may play a role. But, research has not found a clear connection yet. Experts do know that the abnormal proteins are not a result of any certain diet or from eating dietary proteins.

What are the risk factors for monoclonal gammopathies?

The chance of getting MGUS grows with age, but it is not common. There is no risk of monoclonal gammopathies in first-degree family members. This means screening of siblings and children is not needed.

What are the symptoms of monoclonal gammopathies?

MGUS most often causes no symptoms. In fact, monoclonal protein in the blood is often found by accident when doing other routine blood work.

Most people who have abnormal proteins in their blood will never get worse. In some cases, but, these illnesses can develop:

  • Multiple myeloma
  • Non-Hodgkin lymphoma
  • Plasma cell leukemia
  • Primary amyloidosis
  • Solitary plasmacytoma
  • Waldenstrom’s macroglobulinemia

Symptoms of monoclonal gammopathies vary 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

How are monoclonal gammopathies diagnosed?

Once abnormal proteins are found in the blood, more testing is needed. A screening of the blood and sometimes the urine is recommended. This is often done with a lab procedure called electrophoresis. This test separates proteins based on their size and other factors. Depending on the results of those tests, more testing may be done. 

How are monoclonal gammopathies treated?

Because MGUS is not harmful, it doesn’t need to be treated. A diagnosis of MGUS without any other symptoms usually does not call for more testing. But because MGUS may lead to a more serious condition, you’ll need checkups throughout your life. This usually includes regular physical exams and blood work. This will help find problems as early as possible.

Key points

Monoclonal gammopathies are conditions in which abnormal proteins are found in the blood. The most common condition linked with these abnormal proteins is MGUS.

  • It is not cancer.
  • The exact cause of MGUS is unknown.
  • People with MGUS have an increased risk of getting serious diseases of the bone marrow and blood.
  • The chance of getting MGUS increases with age.
  • MGUS most often causes no symptoms.
  • Diagnosis is often done with a lab test called electrophoresis.
  • Because MGUS is not harmful, it doesn’t need to be treated.
  • MGUS may lead to a more serious condition so checkups are needed throughout your life to find problems as early as possible.

Next steps

Tips to help you get the most from a visit to your health care provider:

  • Before your visit, write down questions you want answered.
  • Bring someone with you to help you ask questions and remember what your provider tells you.
  • At the visit, write down the names of new medicines, treatments, or tests, and any new instructions your provider gives you.
  • If you have a follow-up appointment, write down the date, time, and purpose for that visit.
  • Know how you can contact your provider if you have questions.


Medical Reviewers:

  • Sohrabi, Farrokh, MD
  • Ziegler, Olivia Walton, MS, PA-C