Screening for monoclonal gammopathy of undetermined significance is contraindicated.

Incidence of multiple myeloma is about 1.8/100 000. About 3%-5% of adults >50 years of age are diagnosed with monoclonal gammopathy of undetermined significance (MGUS). The prevalence is higher if diagnosis is based on an abnormal ratio of serum free light chains. 300-500 people/10 000 get labelled with a diagnosis of this pre-malignant disorder by using faulty criterion of abnormal light chain ratio. Diagnoses based on an abnormal light chain ratio are incorrect in 96% of instances. However, a large number of people are subjected to psychological trauma and financial toxicity by subjecting them to repeated and invasive testing. If strict criteria requiring the presence of a monoclonal immunoglobulin were used, only about 10 people/10 000 may have MGUS and only one person may progress to multiple myeloma in 10 years. Even that one person gains no benefit from an 'early' diagnosis. Thus, there is only harm and no benefit from screening for MGUS.