The ASO antibody may be found in the blood weeks or months after the strep infection has gone away.
A negative test result means you have likely not had a recent strep infection. The healthcare provider may repeat the test again in 2 - 4 weeks. Sometimes a test that was first negative will come back positive.
Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
What abnormal results mean
An abnormal or positive test means you recently had a strep infection, even if you had no symptoms.
The ASO test may stay positive (sometimes called detectable) for 2 to 4 months afterward you are first infected.
What the risks are
Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight but may include:
Fainting or feeling light-headed
Hematoma (blood accumulating under the skin)
Infection (a slight risk any time the skin is broken)
Bisno AL, Stevens DL. Streptococcus pyogenes. In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2009:chap 198.
Bisno AL. Nonsuppurative poststreptococcal sequelae: Rheumatic fever and glomerulonephritis. In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2009:chap 199.
Comeau D, Heaton K, Gordon A. Rheumatology and musculoskeletal problems. In: Rakel RE, ed. Textbook of Family Medicine. 8th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 32.
Linda J. Vorvick, MD, Medical Director and Director of Didactic Curriculum, MEDEX Northwest Division of Physician Assistant Studies, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.