Growth/differentiation factor 15 is a protein that in humans is encoded by the GDF15 gene. GDF15 was first identified as Macrophage inhibitory cytokine-1 or MIC-1. It is a protein belonging to the transforming growth factor beta superfamily. Under normal conditions, GDF15 is expressed in low concentrations in most organs and upregulated because of injury of organs such as liver, kidney, heart and lung. GDF15 has shown to be a strong prognostic protein in patients with different diseases such as heart diseases and cancer. In cardiovascular tissues it is shown that GDF-15 concentrations increase in response to atherosclerosis, ischemia/reperfusion-injury and heart failure. In patients with coronary artery disease (CAD), GDF-15 is shown to be associated with adverse outcome such as mortality, myocardial infarction, stroke and with bleeding. However, elevated GDF15 levels in diseases such as cancer and heart disease may be the result of inflammation caused by these diseases. Note that GDF15 is necessary for surviving both bacterial and viral infections, as well as sepsis. The protective effects of GDF15 were largely independent of pathogen control or the magnitude of inflammatory response, suggesting a role in disease tolerance.