Understanding the ASO Blood Test Results

Understanding the ASO Blood Test Results

It’s a sore throat that feels bad for a few days, but then starts to get better. A decision is made not to go to the doctor. A few weeks later, you begin to feel some pain in the lower part of your back or you begin to develop a fever. This is when the ASO blood test is primarily used. The information it provides can tell doctors if a recent Streptococcus Group A infection is responsible for a form of kidney disease or rheumatic fever.

In some patients, the ASO blood test may be ordered with other Streptococcus group testing to identify an infection.

Because post-strep infection rates are dropping thanks to the prompt treatment of sore throats, the ASO blood test is seeing less frequent use. It is used today mostly in children who develop symptoms of kidney disease or the signs and symptoms of rheumatic fever so that the cause of those health issues can be determined.

When the ASO Blood Test Is Ordered

The ASO blood test is only ordered when a medical provider believes that a patient’s illness is being caused by a previous strep infection. The symptoms of this type of infection typically develop 2-6 weeks after a sore throat or skin infection as the bacteria which caused the infection have moved to a different location in the body.

If rheumatic fever is thought to be the issue, then patients may experience joint swelling in the ankles, elbows, knees, and wrists. It may be present in one joint only, in several joints simultaneously, or move from joint to joint. Nodules under the skin may develop, as may a rash on the skin, and in some cases the heart may become inflamed to cause shortness of breath, palpitations, and chest pain.

If kidney disease [glomerulonephritis] is suspected, then the symptoms may include fatigue and reduced energy levels. There may also be a reduced level of urine, blood in the urine, joint pain, rashes, swelling, and high blood pressure.

The ASO blood test may be ordered twice, about 2 weeks apart from one another. This will let the medical provider know whether or not the antibody levels this test can detect or rising, falling, or staying level.

What Do My ASO Blood Test Results Mean?

The ASO antibodies that this blood test can detect can begin forming as soon as 7 days after an initial Group A strep infection. The amount of antibodies that can be found in the blood will then peak at 3-6 weeks post-infection. Some antibodies can even be detected several months after the initial infection occurs.

If the ASO blood test results are negative, then this generally indicates that a patient has not had a recent strep infection. A follow-up test 1-2 weeks later may be ordered to confirm this result. Some patients with kidney infections that develop from a strep skin infection, however, may also receive a negative result.

If the ASO blood test results are positive, then this indicates that there are elevated antibody levels in the blood. In follow-up testing, if the results are higher than in the first test, then this indicates that the strep infection is not yet resolved. If the results are lower on follow-up testing, then it may indicate that the infection is resolving.

What Does This Mean For Me?

The ASO blood test results are not designed to let people know what type of disease they will experience or how severe their symptoms may be. It cannot predict whether or not complications will even arise from a recent strep infection. It simply tells you and your doctor a cause for the bothersome signs and symptoms that may be being experienced or to prepare for a future health concern.

For some individuals, corticosteroid treatments can decrease ASO antibody levels. Make sure you tell your medical provider if you are receiving these treatments if they do not know about it already.

Streptococcus can cause a lot of damage when its presence rises to the level of an infection. This is why whenever a child complains about a sore throat for more than 2-3 days, a trip to the doctor should be scheduled. Early interventions with Streptococcus infections can effectively treat health concerns, stop the bacteria from spreading, and prevent the health concerns which would trigger the ASO blood test in the first place.

Only your doctor can diagnose the conditions listed here and recommend a treatment plan. Use this guide to ask questions about your ASO results so that the most effective plan can be created to meet your health needs.