EPO and hyperparathyroidism: It is probably is due to the other factors that affect hemoglobin level in patients under hemodialysis such as reduced erythropoietin production in unhealthy kidneys, severe hyperparathyroidism, acute and chronic inflammatory conditions, aluminum toxicity, reduced lifespan of red blood cells, and concomitant conditions like hemoglobinopathies, hemolysis, and limited access of patients to the recombinant erythropoietin or erythropoiesis-stimulating agents (ESAs) (19).