So far, no changes in the blood tests of patients with ankylosing spondylitis have been found to be directly related to the disease. Some scientific studies have shown that there is a correlation between the platelet count and the width of the red blood cell distribution in patients with ankylosing spondylitis and the inflammatory activity. Of course, this is still under study and has not been widely confirmed as a guide to clinical disease. In addition, in patients with ankylosing spondylitis, if the disease is long, the inflammatory activity of the disease will cause chronic depletion of the body. In some patients, anemia may occur, and the hemoglobin, or hematocrit, may be lower than normal in the blood count.