The amount of a pyrroline-5-carboxylate reductase 1, mitochondrial when measured in blood serum. The trait is level of pyrroline-5-carboxylate reductase 1, mitochondrial in blood serum (OBA_2043123, an Ontology of Biological Attributes entry). Also known as: blood serum pyrroline-5-carboxylate reductase 1, mitochondrial amount.