Anti-Streptolysin - O (ASO) Titre Test

ASO Titre Test Overview

The antistreptolysin o titer test also known as the ASO titer test is a blood test that checks your body for antibodies produced by your immune system in response to group A Streptococcus (GAS) bacteria. These bacteria can cause several infections inside your body and even cause harm to your heart and joint health if left unchecked. The ASO titre test helps study if you have had any streptococcal infections in the recent past. 

Even though this test has the potential to diagnose streptococcal infections, it is used in most cases after the infection has been treated as the ASO levels in your body can show up as long as 7 days after the infection. So, in general, this test is used to check for past streptococcal infections.

When is an ASO Titre Test Prescribed?

An ASO test is prescribed by doctors in three specific situations that are listed below.

• Monitoring the risk of rheumatic fever, which is a rare but serious risk of streptococcal infections.
• Diagnosing streptococcal infections and the conditions they can lead to such as strep throat and scarlet fever.
• To understand and study a patient’s immune history as well as to check if they have been exposed to group A Streptococcus (GAS) bacteria in the past or not.

Components of An ASO Titre Test

The normal range of antibodies in your blood can differ based on age and gender. However, the normal range is generally considered less than 200 for adults and less than 100 for children below the age of 5. Elevated levels of this antibody in your blood can indicate that you have been exposed to group A Streptococcus (GAS) bacteria in the past. It could also help diagnose conditions like strep throat and scarlet fever, which is treated using penicillin shots.

Procedure And Prerequisites

As a blood test the ASO titre test is performed by drawing blood from the veins in the arms of a patient and sending them for testing. Fasting for up to 6 hours before the test may be required for an ASO titre test as a prerequisite. You may also have to disclose the medications you are currently taking to the doctor before the test to ensure they don’t affect the test results.