GDF15 and myelodysplastic syndrome: Indeed, the GDF-15 levels reported in thalassemic patients are consistently higher (up to more than 100,000 pg/ml) than those found in our MDS series (mean levels near 4,500 pg/ml), and in vitro studies have shown that significant hepcidin suppression requires very high levels, i.e. no less than 5,000 pg/ml, being still incomplete at the highest dose of 100,000 pg/ml [10].