Print OverviewMonoclonal gammopathy of undetermined significance (MGUS) is a condition in which an abnormal protein — known as monoclonal protein or M protein — is in your blood. This abnormal protein is formed within your bone marrow, the soft, blood-producing tissue that fills in the center of most of your bones. The disorder occurs most commonly in older men. MGUS usually causes no problems. But sometimes it can progress to more-serious diseases, including some forms of blood cancer. If you have high amounts of this protein in your blood, it's important to have regular checkups so that you can get earlier treatment if it does progress. If there's no disease progression, MGUS doesn't require treatment. Monoclonal gammopathy of undetermined significance (MGUS) care at Mayo ClinicProducts & ServicesBook: Mayo Clinic Family Health Book, 5th EditionNewsletter: Mayo Clinic Health Letter — Digital EditionShow more products from Mayo Clinic SymptomsPeople with monoclonal gammopathy generally don't experience signs or symptoms. Some people may experience a rash or nerve problems, such as numbness or tingling. MGUS is usually detected by chance when you have a blood test for another condition. Request an appointment CausesThe precise cause of MGUS isn't known. Genetic changes and environmental triggers appear to play a role. Risk factorsFactors that increase your risk of developing MGUS include: Age. The average age at diagnosis is 70 years. Race. Africans and African Americans are more likely to experience MGUS than are white people. Sex. MGUS is more common in men. Family history. You may have a higher risk of MGUS if other people in your family have the condition. ComplicationsEach year about 1% of people with MGUS go on to develop certain types of blood cancers or other serious diseases such as: Multiple myeloma Light chain amyloidosis Waldenstrom macroglobulinemia Lymphoma Other complications associated with MGUS include bone fractures, blood clots and kidney problems. By Mayo Clinic Staff Monoclonal gammopathy of undetermined significance (MGUS) care at Mayo Clinic Request an appointment Diagnosis & treatment July 22, 2021 Print Share on: FacebookTwitter Living with monoclonal gammopathy of undetermined significance (mgus)? Connect with others like you for support and answers to your questions in the Blood Cancers & Disorders support group on Mayo Clinic Connect, a patient community. Blood Cancers & Disorders Discussions MGUS and quite high Free Kappa Light Chain and Kappa Lambda Ratio 118 Replies Sat, Jun 03, 2023 chevron-right MGUS: Please, let me know I not alone 143 Replies Fri, Jun 02, 2023 chevron-right Waldenström's Macroglobulinemia 66 Replies Fri, Jun 02, 2023 chevron-right See more discussions Show references Goldman L, et al., eds. Plasma cell disorders. In: Goldman-Cecil Medicine. 25th ed. Philadelphia, Pa.: Saunders Elsevier; 2016. https://www.clinicalkey.com. Accessed April 18, 2019. Ferri FF. Monoclonal gammopathy of undetermined significance (MGUS). In: Ferri's Clinical Advisor 2019. Philadelphia, Pa.: Elsevier; 2019. https://www.clinicalkey.com. Accessed April 18, 2019. Monoclonal gammopathy of undetermined significance (MGUS). Merck Manual Professional Version. https://www.merckmanuals.com/professional/hematology-and-oncology/plasma-cell-disorders/monoclonal-gammopathy-of-undetermined-significance-mgus?query=mgus. Accessed April 18, 2019. Rajhumar SV. Diagnosis of monoclonal gammopathy of undetermined significance. https://www.uptodate.com/contents/search. Accessed April 18, 2019. Rajhumar SV. Clinical course and management of monoclonal gammopathy of undetermined significance. https://www.uptodate.com/contents/search. Accessed April 18, 2019. AskMayoExpert. Monoclonal gammopathy of undetermined significance (MGUS) (adult). Rochester, Minn.: Mayo Foundation for Medical Education and Research; 2019. Morrow ES Jr. Allscripts EPSi. Mayo Clinic, Rochester, Minn. Feb. 8, 2019. Pruthi RK (expert opinion). Mayo Clinic, Rochester, Minn. April 26, 2019. 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