Iron Deficiency and FGF23 Regulation in CKD and HF

Iron is a key part of our red blood cells which bring oxygen to our body's tissues. Without iron, our blood cannot carry oxygen. The body normally gets iron through diet and it also re-uses iron from old red blood cells. When iron stores are low, patients get iron deficiency anemia. This can happen because patients lose more red blood cells and iron than the body can replace, the body does not do a good job at absorbing iron from the diet, or the body is able to absorb iron but patients are not getting enough iron from their diets. Many patients with chronic diseases such as CKD and CHF also have iron deficiency anemia. Iron deficiency may also cause a hormone in the body named FGF23 to rise. FGF23 is a hormone that is made in bone and has an important role in the heart and kidney. When the kidneys are not working properly, as in CKD, or when the heart is not pumping correctly, as in CHF, FGF23 levels in the blood go up. Many patients with CKD or CHF also have low levels of iron. In these cases, FGF23 levels may rise even more. Too much FGF23 in the blood may lead to an increased risk of heart problems and accelerate loss of kidney function. The best way to control FGF23 levels in the blood in CKD and CHF is not known. The investigators are conducting a 6-week iron deficiency anemia study on healthy individuals,individuals with CKD, and individuals with CHF to find out if treating iron deficiency anemia with intravenous iron sucrose therapy can safely and successfully lower FGF23 levels. Iron sucrose has been shown to lower FGF23 in animal models. The short term effects of iron sucrose on FGF23 levels in CKD and CHF are not known.