In rheumatic fever, the value of anti-streptolysin O (ASO) generally needs to be at least greater than 400. Since this is a disease closely related to streptococcal infection, the ASO level often rises significantly during the active stage of the disease. Of course, diagnosis cannot rely solely on this one indicator. It also needs to be judged based on the patient's typical clinical symptoms and relevant evidence of streptococcal infection. Therefore, a throat swab culture is also required.In addition, rheumatic fever is mainly a pediatric-related disorder, commonly seen in school-age children and adolescents. It often causes joint inflammation, carditis, and related lesions in the skin, brain, blood vessels, etc.