Albertine Donker

TSAT/Hepcidin Ratio discriminates TMPRSS6 -related Anemia from IDA 285 8 TSAT/hepcidin ratio siginificantly differs between IRIDA and IDA The TSAT/hepcidin ratio was significantly lower in IRIDA patients (median 0.7 %/nM, range 0.1-9.1 %/nM) than in IDA controls (median 16.7 %/nM, range 8.0-44.0 %/nM, p =0.000) ( Table 2, Figure 1 ). Furthermore, we divided the IRIDA group in mono-allelic and bi-allelic affected cases, since patients with a pathogenic mono-allelic TMPRSS6 defect tend to have lower hepcidin levels compared to bi-allelic affected patients according to our previous observations. 11 Indeed, the TSAT/hepcidin ratio was statistically lower in the mono- allelic affected group, median 0.5 %/nM (range 0.1-1.0 %/nM) versus median 1.4 %/ nM (range 0.3-9.1 %/nM, p =0.003) in the bi-allelic affected group. For both bi-allelic and mono-allelic IRIDA patients the TSAT/hepcidin ratio was significantly lower than in IDA controls ( p =0.000 and p =0.000 respectively ). For comparison of our results with previously published results by Heeney et al 13 , who uses non-standardized hepcidin values, we also converted our data to the TSAT/log 10 (hepcidin). However, using this ratio for much lower standardized hepcidin values, after log transformation the ability to discriminate between IRIDA and IDA disappeared.