A 10-year-old girl develops subcutaneous nodules over the skin of her arms and torso 3 weeks after a bout of acute pharyngitis. She manifests choreiform movements and begins to complain of pain in her knees and hips, particularly with movement. A friction rub is heard on auscultation of her chest. An abnormality detected by which of the following serum laboratory findings is most characteristic of the disease affecting this girl?
Acute rheumatic fever can involve any or all layers of the heart. Because rheumatic fever follows a group A streptococcal infections, the antihyaluronidase, anti-DNase, and anti-streptolysin O (ASO) titers are often elevated. The strains of group A streptococci that lead to acute rheumatic fever are less likely to cause glomerulonephritis, so an elevated creatinine level is unlikely. The ANA level could be elevated in systemic lupus erythematosus, which is most likely to produce serous pericarditis. A positive rapid plasma reagin test suggests syphilis, but the clinical features here are not those of syphilis, and cardiovascular syphilis is one form of tertiary syphilis that develops decades after the initial infection. Cardiac troponins are markers for ischemic myocardial injury. Although their levels may be elevated because of the acute myocarditis that occurs in rheumatic fever, this change is not a characteristic of rheumatic heart disease.
Anti-streptolysin O antibody titer
Antinuclear antibody titer
Creatinine level
Rapid plasma reagin test
C.V.S