Keryx Biopharmaceuticals, Inc. is a biopharmaceutical company. The Company is focused on the development of products for the treatment of renal diseases. Its lead product Auryxia (ferric citrate), an oral, absorbable iron-based compound, received marketing approval from the United States Food and Drug Administration (FDA), for the control of serum phosphorus levels in patients with chronic kidney disease (CKD) on dialysis. The approval of Auryxia was based on data from its Phase III registration program, in which Auryxia effectively reduced serum phosphorus levels to well within the National Kidney Foundation Kidney Disease Outcomes Quality Initiative (KDOQI) guidelines range of 3.5 to 5.5 mg/dL. In addition to the effects on serum phosphorus levels, Auryxia's pharmacodynamic properties resulted in increased ferritin, iron and transferrin saturation (TSAT).