Albertine Donker

TSAT/Hepcidin Ratio discriminates TMPRSS6 -related Anemia from IDA 283 8 unexplained IDA controls responsiveness to oral or parenteral iron was assessed. Thirteen out of 18 patients responded to iron supplementation, suggesting IDA not related to inappropriately increased serum hepcidin levels relative to body iron related to a TMPRSS6 defect. In 3 out of 18 patients no iron therapy was given because of spontaneous Hb normalization without treatment, gastrointestinal side-effects after iron supplementation in the past and refusal of iron therapy. In all IDA controls, iron therapy was initiated after blood withdrawal for assessment of the TSAT/hepcidin ratio. Comparison of baseline characteristics. At the time of TSAT/hepcidin assessment, IRIDA patients had a median age 29 years (range 1-58 years), which was significantly younger than the IDA controls, who had a median age of 62 years (range 18-90 years, p =0.000, 2-sided Mann-Whitney U test). Women were equally represented in both groups ( p =0.797, 2-sided Chi-Square test. In IRIDA patients, data on BMI and eGFR were not available, but we anticipated that the proportion of IRIDA patients with overweight or obesity and impaired eGFR is lower because of the younger age compared to the IDA controls. In the IRIDA group MCV was significantly lower and ferritin significantly higher in comparison to the IDA group (p=0.010, 2-sided Mann-Whitney U test). Table 1A. Clinical, biochemical and genetic characteristics of patients with TMPRSS6- related IRIDA Patient characteristics N Median or count Range or percentage Age at presentation with anemia, years 21 10 0-57 Age at time of assessment for IRIDA and TSAT/ hepcidin determination, years 20 29 1-58 Women 21 16 76 Systemic disease (i.e. diabetes mellitus) 21 1 5 Hb, g/dL a 20 11.5 6.4-13.8 MCV, fL a 20 60.5 52.0-87.0 Ferritin, µg/L a 20 93 23.0-934 TSAT, % a 21 6.1 1.9-20.0 CRP, mg/L 15 <0.5 0.5-8.0 TMPRSS defect • Bi-allelec • Mono-allelic 21 11 10 11 10 52 48 a at time of assessment of diagnosis of IRIDA and determination of TSAT/hepcidin ratio, after iron treatment had been given