ASOT Blood Test | London Blood Tests |

Detect recent streptococcal infection with the Antistreptolysin O Titre (ASOT) blood test for £88. UKAS-accredited testing, GP review optional.

The Antistreptolysin O Titre (ASOT) Blood Test measures antibodies produced in response to Group A Streptococcusinfection. It is commonly used to investigate recent or past streptococcal infections and related complications such as rheumatic fever and post-streptococcal glomerulonephritis. Testing is performed in a UKAS-accredited laboratory, with an optional GP consultation.

What is an Antistreptolysin O Titre (ASOT) Test?

Antistreptolysin O (ASO) is an antibody produced by the immune system following infection with Group A beta-haemolytic Streptococcus, the bacteria responsible for conditions such as strep throat, scarlet fever, and skin infections.

ASOT testing does not detect the bacteria itself, but rather the immune response to it. Antibody levels typically rise 1–3 weeks after infection, peak at around 3–5 weeks, and then gradually decline over several months.

The ASOT test is particularly useful when complications are suspected after a streptococcal infection has resolved, helping clinicians confirm recent exposure.

At London Blood Tests, ASOT is measured using validated immunoassay techniques aligned with UK infectious disease standards.

Benefits of the ASOT Test

1. Confirms Recent Streptococcal Infection
   Detects immune response even after symptoms have resolved.
2. Supports Diagnosis of Post-Strep Complications
   Essential for investigating rheumatic fever and kidney inflammation.
3. Useful When Swab Tests Are Negative
   Helps confirm infection retrospectively.
4. Assists Autoimmune & Inflammatory Investigations
   Identifies streptococcal triggers for immune-mediated conditions.
5. Non-Invasive & Simple
   Requires only a standard blood sample.
6. Clinically Relevant for Children and Adults
   Used in both paediatric and adult medicine.
7. Optional GP Consultation for Interpretation
   Results can be reviewed with a GP to guide further testing.

Why Do I Need an ASOT Blood Test?

You may benefit from an ASOT test if you have symptoms or conditions that may follow a streptococcal infection, including:

• Persistent joint pain or swelling
• Fever with no clear cause
• Skin rashes
• Blood or protein in urine
• Fatigue following a recent sore throat
• Suspected rheumatic fever

Testing is commonly recommended if:

• Symptoms appear weeks after a throat or skin infection
• Streptococcal infection was suspected but not confirmed
• There is concern about immune-related complications

Because streptococcal complications can be serious, early confirmation supports prompt management.

How the Test Works

In-Clinic Testing at London Blood Tests

1. Book Your Appointment
• Book online or by phone at your chosen clinic.
• No fasting required.
2. Pre-Test Review
• Inform the clinician about recent sore throat, fever, or skin infection.
3. Sample Collection
• A trained phlebotomist collects a venous blood sample.
• Takes 5–10 minutes.
4. Laboratory Analysis
• Sample analysed in a UKAS-accredited laboratory.
5. Quality Control
• Results verified before release.
6. Results Delivery
• Results typically available within 5–10 business days.
7. Optional GP Consultation
• Review results and clinical implications with a GP.

At-Home Blood Draw (Home or Hotel Phlebotomy – UK-Wide)

1. Book Your Visit
• Arrange a phlebotomist home or hotel visit.
2. Professional Collection
• Certified phlebotomist collects your blood sample.
3. Secure Transport
• Sample couriered same day to the laboratory.
4. Laboratory Testing
• Analysis identical to clinic testing.
5. Results & Follow-Up
• Results delivered online, GP review optional.

Your ASOT Test Results – Explained

ASOT results are reported in IU/mL.

Typical UK reference guidance:

• Adults: < 200 IU/mL
• Children: < 150 IU/mL (may vary by age)

Interpretation:

• Normal ASOT: no recent streptococcal infection
• Raised ASOT: recent or past streptococcal infection
• Very high or rising titres: suggest recent infection or ongoing immune response

Sometimes, paired samples taken weeks apart are used to confirm rising titres.