What does Positive Anti-streptolysin O titre (ASO) blood test means?

What is ASO?
It is abbreviated to (Anti-streptolysin O), which is the name given to antibodies against streptolysin O from bacteria classes of group A, C and G streptococci, it is Bacteria are able to disintegrate blood cells and make big troubles in the patient’s body.
Why my ASO level is elevated in blood test results?
The main cause rising ASO titre in ASOT test is the tonsillitis disease especially for children of ages under 15 years old, but ASO level in blood can be elevated by many other diseases as post post-streptococcal complications such as:
Ear infection
Guttate psoriasis
Peritonsillar abscess
Rheumatic fever
Scarlet fever
1- Rheumatic fever complications
A noncontagious acute fever marked by inflammation and pain in the joints. it chiefly affects young people and also it is caused by a streptococcal infection.
Blood test results of patients may be as follow:
RF test: greater than 30 unit (normal up to 30 U)
ASO titre: 200 – 400 mg/dl, medical significance may be for IgG antibodies, meant by old infection or immunized persons too.
CRP test: greater than 24 mg/dl, medical significance of positive CRP results in patient’s serum indicate severity of inflammation.
ESR first hour, 2nd Hour: >40, >80 respectively
Symptoms results from High ASO titer in the blood for RA patients:
· Fever
· Joint swelling and pain in more than one joint, especially in the ankles, knees, elbows and wrists, sometimes moving from one joint to another
· Small, painless nodules under the skin
· Rapid, jerky movements (Sydenham’s chorea)
· Skin rash
· Sometimes the heart can become inflamed (carditis); this may not produce any symptoms but also may lead to shortness of breath, heart palpitations, or chest pain.
2- Complication of Glomerulonephritis
It is a cute inflammation of the kidney, typically caused by an immune response, ASOT test show positive result for patients with nephritic syndrome, which due to post-streptococcal complications (sequelae) an inflammation to glomerules of the kidney cause the High ASO titer.
Glomerulonephritis solely occur after repeated infection with streptococcus bacteria as post-streptococcal complications as mentioned.
Lab test results for nephritic syndrome patients:
Serum ASOT test: 200 – 400 unit
Serum CRP tests: > 12, but not so high
ESR: elevated
RF: Negative
Urine: Over count RBC and Pus, and Presence of Albumin (+++) and Cellular casts
Symptoms shown after nephritis:
Fatigue, decreased energy
Decreased urine output
Bloody urine
Joint pain
Swelling (edema)
High blood pressure
3- Complications due to Strep throat
Also called Streptococcal pharyngitis, It is an infection of the throat caused by hemolytic streptococci and marked by fever and inflammation of the tonsils, medically called tonsillitis, also diseases lie that as Sore throat, Group A streptococcal infection, Fever, Tonsil inflammation, and Sinus infection.
4- Strep infection results in high ASO titre
It is a genus of spherical gram-positive bacteria belonging to the phylum firmicutes and the lactic acid bacteria group.
Infected persons with Strep throat usually feel such symptoms below:
· loss of appetite
· abnormal taste
· Headache
· Nausea
And Patients appear on signs such as
· feel sick about: 2 to 5 days after infection
· fever from next day of sick felling
· feel swollen, tender glands in your neck with red sore throat with white patches
5- Complication accompany the Scarlet fever
It is an infectious bacterial disease affecting esp. children, and young aged people.
Easy and simple guidance steps should be follow when your ASOT blood test show high values

  1. If ASO test under 200 mg/dl, low concentration which means normal level: means person has not had a recent strep infection, to confirm test results repeat ASO test after 10 – 15 days because ASO levels peak at about 4 to 6 weeks after the infection.
  2. if ASO test is positive and elevated greater than or equal to 400 mg/dl, it is likely the person to has recent infection and should be treated.
  3. after medication course, carry ASO test again to be negative, and confirmatory test called anti-DNase B test. If negative, then the body is completely cured.
  4. ASO titre test have high accuracy but to be assured of Streptococcal infection, a throat swab can be tested (cultured), results come after 2 – 4 days after culturing the sample.

More Case studies of Positive and abnormal Anti-streptolysin O titre results
What is Strep throat treatment and how to lowering ASO levels?
Tonsillitis and streptococcal infection cause inflammation to tonsils may be treated naturally by Drink warm liquids and Gargle several times a day with warm salt water (1/2 tsp of salt in 1 cup water). Or by take antibiotics as Penicillin or amoxicillin for more than a week.
for more testing panels and medical information:
Can my ASO result be false?
What does the reference range means?
Can High ASO titre cause heart disease?

Dr.Megan Ralf

A Medical laboratory Scientist who devoted his life to medical and laboratory sciences, writes his everyday expertise dealing with various pathological conditions through laboratory diagnosis of different body fluids, also participating in many workshops for first aids, infection control, and urgent care. Also Dr Megan Ralf coaching many medical teams.

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