Anti-Streptolysin O

RED, PST

Serum (gold top) tube or Lithium Heparin Plasma (green top) tube

Daily upon receipt

Birth - 16 Years:      0 - 240 IU mL
16 Years and Older: 0 - 200 IU mL

Group A ß-hemolytic streptococci (Streptococcus pyogenes) infections can lead to development of post-streptococcal complications, including rheumatic fever, acute glomerulonephitis and reactive arthritis.  Because these sequelae usually do not present until 2-3 weeks after infection when tests for streptococci are no longer positive, clinical diagnosis is aided by measuring antibody response against extracellular products of Group A streptococcus, including streptolysin O, DNAase B, hyaluronidase, NADase, and streptokinase. Antistreptolysin O (ASO) is the antibody response most often measured to provide serological evidence of recent infection of Group A streptococcus in patients suspected of having acute rheumatic fever or acute glomerulonephritis.  ASO titers are elevated in the sera of 80% to 85% of patients with rheumatic fever and in 95% of patients with acute glomerulonephritis.  ASO titers begin to rise about 1 week after infection, peak 2–4 weeks later, and then usually fall to pre-infection levels within 6–12 months.  Streptococcal infections of the upper respiratory tract generally result in strong ASO response, whereas the ASO response is attenuated following infections of the skin. Confirmation of antecedent streptococcal infection can be improved by measuring other antibody responses such as anti-DNAase B.