level of Phosphatidylcholine (16:0_20:4) in blood serum (OBA_2045076, an Ontology of Biological Attributes identifier) is the amount of a PC(16:0_20:4) when measured in blood serum. Also known as: blood serum PC(16:0_20:4) amount, level of PC(16:0_20:4) in blood serum.