Being asymptomatic, monoclonal gammopathy of undetermined significance and smoldering multiple myeloma are typically diagnosed fortuitously by detecting a myeloma protein on serum protein electrophoresis tests done for other purposes. MGUS is a relatively stable condition afflicting 3% of people aged 50 and 5% of people aged 70; it progresses to multiple myeloma at a rate of 0.5–1% cases per year; smoldering multiple myeloma does so at a rate of 10% per year for the first 5 years, but then falls off sharply to 3% per year for the next 5 years and thereafter to 1% per year.
