The amount of a 3',5'-cyclic-AMP phosphodiesterase 4C when measured in blood serum. The trait is Ontology of Biological Attributes entry OBA_2042821 (level of cAMP-specific 3',5'-cyclic phosphodiesterase 4C in blood serum). Also known as: blood serum 3',5'-cyclic-AMP phosphodiesterase 4C amount.