Subsequent to the release of the CE-marked HLC kits, there have been a number of studies in which the reference intervals for the Hevylite assays have been reported. Guirtarte et al.  measured IgM HLC in blood donor sera on both the BNII and SPAPLUS instruments, and concluded that reference intervals on each instrument were similar, and comparable to the intervals in the product inserts. Katzmann et al.  published reference intervals for all Hevylite specificities on the BNII, and commented that the reference ranges were similar to those previously published by Bradwell et al. . Katzmann et al. report similar reference intervals in their most recent publication . Here they defined both 95% and 99% reference intervals for the IgG, IgA and IgM HLC ratios, and used the 99% intervals to determine clonality. The results from these studies are summarised in Tables 10.1, 10.2 and 10.3.