The amount of a PE(16:0_20:4) when measured in blood serum. The trait is level of Phosphatidylethanolamine (16:0_20:4) in blood serum (Ontology of Biological Attributes term OBA_2045137). Also known as: blood serum PE(16:0_20:4) amount, level of PE(16:0_20:4) in blood serum.