From the Guidelines
Small MGUS is a premalignant condition that requires regular monitoring without specific treatment, with a low risk of progression to multiple myeloma or related conditions, approximately 1% per year, as indicated by studies such as 1. The condition is characterized by the presence of a small amount of monoclonal protein in the blood without evidence of multiple myeloma or related disorders.
- Patients with IgG MGUS less than 15 g/L, normal free light chain ratio, and non-IgM type have a low risk of progression to multiple myeloma or related conditions.
- No medications or interventions are needed for small MGUS itself, but patients should be educated about symptoms that warrant immediate medical attention, such as bone pain, unexplained fatigue, recurrent infections, or symptoms of hypercalcemia.
- The condition results from abnormal plasma cell proliferation in the bone marrow producing monoclonal immunoglobulins, but at levels insufficient to cause organ damage or meet criteria for malignancy.
- Lifetime monitoring is important as approximately 1% of cases per year will progress to more serious conditions, and patients should have follow-up appointments every 6-12 months with serum protein electrophoresis, complete blood count, calcium levels, and kidney function tests, as recommended by 1 and 1.
- A baseline BM examination or skeletal radiography is not routinely indicated if the clinical evaluation, complete blood count, serum creatinine and calcium values suggest MGUS, but a BM is required if the patient has unexplained anemia, renal insufficiency, hypercalcemia, or bone lesions, as stated in 1 and 1.
From the Research
Definition and Prevalence of MGUS
- Monoclonal Gammopathy of Undetermined Significance (MGUS) is defined as a serum M protein level of less than 3 g/dL, less than 10% clonal plasma cells in the bone marrow, and the absence of end-organ damage 2.
- The prevalence of MGUS is 3.2% in the white population but is approximately twice that high in the black population 2.
- MGUS is found in approximately 3% of persons > 70 years of age and in about 1% of those > 50 years old 3.
Risk of Progression
- MGUS may progress to multiple myeloma, AL amyloidosis, Waldenström macroglobulinemia, or lymphoma 2, 3.
- The risk of progression is approximately 1% per year, but the risk continues even after more than 25 years of observation 2, 3.
- Risk factors for progression include the size of the serum M protein, the type of serum M protein, the number of plasma cells in the bone marrow, and the serum free light chain ratio 2, 3.
Management and Monitoring
- Patients with MGUS must be followed up for their lifetime 2, 3.
- Regular monitoring is necessary to detect potential progression to a malignant condition 4, 5.
- Patients with MGUS can be risk-stratified on the basis of the amount and type of their monoclonal protein as well as whether they have an abnormal light-chain ratio 4.
Clinical Significance
- MGUS may be associated with many disorders, including lymphoproliferative diseases, leukemia, von Willebrand's disease, connective tissue diseases, and neurologic disorders 3.
- A fraction of patients with MGUS develop clinical manifestations related to the monoclonal gammopathy despite not fulfilling criteria of multiple myeloma or other lymphoproliferative disorder, constituting an emerging clinical issue coined as monoclonal gammopathy of clinical significance (MGCS) 6.