Carbohydrate Antigen 19.9 or the Cancer Antigen 19.9 is a protein on the top of cells. The normal range of CA 19.9 in the blood of a healthy individual is 0-37 U/mL.. This test is done to measures the level of antigens in the serum. Methods for testing the presence of CA 19-9 and the results vary from lab to lab. It is advised that you have the tests done by the same method and if possible in the same laboratory. It is also noted that an elevated CA 19.9 level cannot always signifies pancreatic cancer.