EPO and chronic kidney disease: Anemia is believed to be caused by a combination of erythropoietic stress induced by elevated advanced glycation end products, oxidative stress, endothelial dysfunction, decreased levels of erythropoietin (EPO) due to chronic kidney disease, and medications such as metformin, angiotensin receptor blockers (ARBs), and angiotensin-converting enzyme inhibitors (ACEis) [13,14].