A compound attribute that is the ratio of amount of tumor necrosis factor receptor superfamily member 13B (human) in blood to amount of tumor necrosis factor ligand superfamily member 13B (human) in blood. The trait is TNFRSF13B/TNFSF13B protein level ratio in blood (OBA_2052987, an Ontology of Biological Attributes entry). Also known as: the ratio of amount of tumor necrosis factor receptor superfamily member 13B (human) in blood to amount of tumor necrosis factor ligand superfamily member 13B (human) in blood.