The amount of a heparan sulfate glucosamine 3-O-sulfotransferase 4 when measured in blood serum. The trait is Ontology of Biological Attributes id OBA_2041933 (level of heparan sulfate glucosamine 3-O-sulfotransferase 4 in blood serum). Also known as: blood serum heparan sulfate glucosamine 3-O-sulfotransferase 4 amount.