Ontology of Biological Attributes term OBA_2045116 (level of Phosphatidylcholine (O-16:0_20:4) in blood serum) is the amount of a phosphatidylcholine O-16:0_20:4 when measured in blood serum. Also known as: blood serum phosphatidylcholine O-16:0_20:4 amount, level of phosphatidylcholine O-16:0_20:4 in blood serum.