Growth differentiation factor 15 （GDF-15） is a polypeptide hormone belonging to the transforming growth factor β （TGF-β） superfamily. GDF-15 is highly expressed in placenta and is expressed at lower levels in kidney, pancreas, prostate and colon. Similarly to other TGF-beta family proteins, GDF-15 is synthesized as a large precursor protein that is cleaved at the dibasic cleavage site （RXXR） to release the carboxy-terminal domain. GDF-15 has been studied to have a wide range of biological functions in physiology and pathology, especially in aging, cancer, and metabolic processes.