level of Phosphatidylcholine (O-18:2_18:2) in blood serum (OBA_2045134, an Ontology of Biological Attributes identifier) is the amount of a Phosphatidylcholine (O-18:2_18:2) when measured in blood serum. Also known as: blood serum Phosphatidylcholine (O-18:2_18:2) amount.