Chapter 32

When the monoclonal IgM concentration is low, accurate quantification by SPE or capillary zone electrophoresis (CZE) may be difficult. In such cases, IgM HLC may provide a more reliable quantitative assessment (Figure 32.6) [716][717]. Hevylite analysis may also be useful in cases where monoclonal proteins form multimers or co-migrate with other serum protein peaks (Section 17.4) [127].

Boyle et al. [901] assessed the diagnostic sensitivity of IgM HLC in 78 WM patients at presentation and showed that IgMκ/IgMλ HLC ratios were abnormal in all cases, including 12/78 patients with SPE bands that were non-quantifiable and 4/78 patients with total IgM concentrations within the normal range (Figure 32.7). Similar findings were reported by Koulieris et al. [680] who reported a diagnostic sensitivity for IgM Hevylite in WM of 97%.