Clinical conditions known to influence circulating hepcidin levels. Clinically relevant conditions include CKD,^11,16  RBC transfusions,²⁷  iron administration,^28.29  replete iron stores,¹ TMPRSS6 variants,^30,31  infections/inflammatory disorders,^32-34  ineffective erythropoiesis,^3,49  hypoxia,^35,36  administration of erythropoietic stimulating agents,³⁷  chronic liver diseases,³⁸  alcohol abuse,³⁹  HCV,⁴⁰  hemochromatosis-related mutations,^1,28,41,42  and administration of the sex hormones testosterone⁴³  and estrogens.^44,45  CKD, chronic kidney disease; GFR, glomerular filtration rate; HCV, hepatitis C virus; HH, hereditary hemochromatosis; IDA, iron deficiency anemia; RBC, red blood cell; TMPRSS6 (transmembrane protease serine 6), the gene encoding for matriptase-2.