FAM3B/GUCA2A protein level ratio in blood (OBA_2055352, an Ontology of Biological Attributes term) can be described as follows. A compound attribute that is the ratio of amount of protein FAM3B (human) in blood to amount of guanylin (human) in blood. Also known as: the ratio of amount of protein FAM3B (human) in blood to amount of guanylin (human) in blood.