Overview of Anti Streptolysin O Titer
What is Anti Streptolysin O Titer?
Preparation for Anti Streptolysin O Titer
- No special preparation required
Why Get Tested for Anti Streptolysin O Titer?
The ASO Titer Test is performed:
· To help determine if conditions like rheumatic fever or glomerulonephritis have occurred as complications of a Streptococcus infection
· To determine the presence of a Streptococcus infection in case the patient has received antibiotics
Understand more about Anti Streptolysin O Titer
Streptococcus pyogenes or Group A Streptococcus is a bacteria which causes a number of infections like throat infections, skin infections like pyoderma, etc. These infections are easily recognizable and treated with the help of antibiotics. However, if the Streptococcus infection is left untreated or improperly treated, it may lead to complications like rheumatic fever, glomerulonephritis, scarlet fever, heart and kidney damage, joint inflammation, swelling etc.
Symptoms caused by an infection of Group A Streptococcus bacteria are caused mainly due to a toxin called Streptolysin O which is secreted by these bacteria. The body produces antibodies against Streptolysin O called Antistreptolysin O (ASO). ASO antibodies are produced by the body a week to a month after an infection. Levels peak after about 3 to 5 weeks after the condition develops, after which they slowly taper off as the condition resolves. Increase in ASO levels is greater in case of throat infections than in skin infections. The ASO Titer Test is performed to measure the levels of ASO in blood to help diagnose a Streptococcus infection and complications which may have arisen from the infection.
What Results of Anti Streptolysin O Titer mean?
Normal ASO level:
Children (up to 12 years of age): Below 150 IU/ml
Adults (above 12 years of age): Below 200 IU/ml
Higher than normal ASO levels indicates an infection of Streptococcus bacteria.
Low ASO titer indicates no recent infection which is confirmed if the low levels persist in the subsequent test performed after 10 to 15 days. Other tests like Anti-DNase B Test can also be performed.
Higher than normal ASO titer levels and continuously rising ASO titer in subsequent tests indicates a recent and ongoing infection.
High ASO levels which decline subsequently indicate a Streptococcus infection which is resolving or being cured.
A positive result in the ASO test (Higher than normal ASO levels) confirms a past Streptococcal infection. A positive result can thus help in the diagnosis of conditions like Poststreptococcal Glomerulonephritis (PSGN), Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcus (PANDAS), and rheumatic fever.
Note: ASO Test results may be negative (within normal range) in upto 20% of patients suffering from Acute Rheumatic Fever (ARF). Other tests may be performed to confirm the condition in these cases.
Patient Concerns about Anti Streptolysin O Titer
Frequently Asked Questions about Anti Streptolysin O Titer