Monoclonal gammopathy of undetermined significance (MGUS)

While most people with monoclonal gammopathy of undetermined significance, or ‘MGUS’, will notice no effect on their general health, a small number of patients will go on to develop myeloma.

What is MGUS?

Monoclonal gammopathy of undetermined significance, or ‘MGUS’, is a benign (non-cancerous) condition. MGUS does not cause any symptoms and is usually diagnosed incidentally when tests are performed to investigate other problems. It does not require any treatment.

In MGUS, abnormal plasma cells in the bone marrow release an abnormal protein, known as paraprotein. MGUS is characterised by the presence of this abnormal protein in the blood and/or urine.

While most MGUS patients have a stable condition which has no effect on their general health, a small proportion of patients will go on to develop a cancer called myeloma. MGUS can also progress to other conditions such as Waldenström’s macroglobulinaemia, AL amyloidosis or lymphoma.

How is MGUS diagnosed and what are its symptoms?

MGUS is not associated with any symptoms, so the abnormal protein is usually discovered when tests are being performed to rule out other health issues. Once the abnormal protein is discovered, it is important to make sure that it is not due to a more serious diagnosis such as myeloma, and so further tests are likely to be carried out.

How is MGUS managed?

Current guidance recommends that MGUS is actively monitored but not treated. MGUS patients are usually checked every 3-4 months for the first year following diagnosis. The checks can then be reduced to every 6-12 months as long as no symptoms develop.

We have a free MGUS Diary for patients, where you can keep a record of your test results and learn more about how MGUS is monitored. Click on the link below to find out more.

Middle faced woman sat at desk using a computer. She has blonde hair and is wearing a white short sleeved shirt and a headset with a microphone.

Speak to one of our Myeloma Information Specialists

If you need information, emotional support, practical advice or just a listening hear, our Myeloma Information Specialists are here for you. You can call them on 0800 980 3332 (Mon – Fri, 9-5) or email them on