When screening for plasma cell disorders, the desirability of obtaining urine samples to test for uBJP has long been recognised, and included in diagnostic guidelines for more than a decade (e.g. IMWG guidelines, 2003 ). In spite of this, published audits and studies have usually indicated that less than 50% of sera that were sent to laboratories to screen for monoclonal gammopathies had an accompanying urine sample. Recent National guidelines recommend the use of SPE and sFLC analysis without the need for uBJP testing, to screen for a monoclonal protein (Section 25.7). The authors comment that poor urine compliance could have resulted in missed diagnoses if the sFLC test was not performed as an alternative. A similar conclusion was reached by Drayson et al.  who compared the characteristics of LCMM and IIMM patients at diagnosis (Section 20.1). LCMM patients had a significantly worse performance status and greater incidence of multiple lytic lesions and the authors suggest that that this might reflect a delay in diagnosis of LCMM, when no monoclonal protein can be detected by serum electrophoresis and no urine sample is provided. The authors also suggest that assessment of sFLCs may mitigate this problem.
Table 23.5 records the urine compliance from recent screening studies. Irrespective of the relative sensitivities of urine electrophoresis and sFLC analysis for monoclonal FLC detection, urine can only be examined if it is provided. Table 23.5 demonstrates that one very clear, practical advantage of using sFLC analysis is the fact that it can be performed on the same sample that is provided for SPE/sIFE analysis.
|Screening study||Number of sera||Urine compliance|
|Hill et al. (2006) ||923||40%|
|Beetham et al. (2007) ||932||52%|
|Abadie et al. (2009) ||-||35%|
|Robson et al. (2009) ||653||<5%|
|Holding et al. (2011) ||753||17%|
|McTaggart et al. (2011) ||2799||21%|
Table 23.5. Published urine compliance rates.