A compound attribute that is the ratio of amount of carbonic anhydrase 13 (human) in blood to amount of peptidyl-prolyl cis-trans isomerase B (human) in blood. The trait is Ontology of Biological Attributes term OBA_2055721 (CA13/PPIB protein level ratio in blood). Also known as: the ratio of amount of carbonic anhydrase 13 (human) in blood to amount of peptidyl-prolyl cis-trans isomerase B (human) in blood.