GDF15 and neoplasm: Studies in ICUAW have supported a potential autocrine or paracrine effect of GDF-15 on muscle mass.13 A GDF-15 antibody has been shown to be able to prevent the muscle loss seen in mice xenografted with human tumours which secreted GDF-15 confirming its endocrine effects.30 Our data also suggest that GDF-15 mediates muscle loss in an endocrine manner, with the pulmonary vascular endothelium and plexiform lesions31 acting as the potential source of raised circulating GDF-15 levels.