Urine provision remains an important issue in the serum versus urine debate; lack of urine with diagnostic serum samples has repeatedly been reported (Section 23.5). Even once a diagnosis of monoclonal gammopathy has been confirmed, problems with urine provision continue. In a study of 496 newly diagnosed monoclonal gammopathy patients by Holding et al. , only 30% of serum samples had a matched urine sample provided within 7 days; this increased to 57% within 90 days. Foster et al.  reviewed laboratory test usage to monitor 4591 MM patients followed at community clinics across the United States. At baseline, 58.1% received a sFLC test and 79.2% received an SPE test but only 27.7% received a UPE test. In the subgroup of patients with LCMM, 84.8% were followed with sFLC while only 15.2% were followed by UPE. The authors conclude that despite 24-hour urine tests being included in IMWG guidelines, they are often not performed in routine clinical practice, which may reflect the impracticalities of urine collection and storage.
Overall, the annual UK National Pathology Benchmarking Review for 2007/2008 reported that the number of UPE tests performed was much lower than serum protein electrophoresis (SPE), comprising only 14% of SPE requests (298,392) . Recent National guidelines omit the use of urine BJP testing to screen for a monoclonal protein because of poor compliance, and the potential to miss diagnoses (Section 25.7). The authors of a screening study carried out at New Cross Hospital, Wolverhampton, UK, reported an extremely poor provision of matched urine samples (<5%) and concluded that “the debate over the relative merits of the sFLC assay versus uBJP analysis borders on the irrelevant” .