The amount of a PC(15:0_18:2) when measured in blood serum. The trait is level of Phosphatidylcholine (15:0_18:2) in blood serum (OBA_2045065, an Ontology of Biological Attributes term). Also known as: blood serum PC(15:0_18:2) amount, level of PC(15:0_18:2) in blood serum.