Streptococcal serology – ASO, Blood

Diagnostic Use

Streptococcal antibody tests are used primarily for aiding diagnosis of post streptococcal complications of ARF (Acute Rheumatic Fever) and post Streptococcal glomerulonephritis.
Timing of streptococcal serology for evidence of preceding Group A streptococcal infection is important. Streptococcal antibodies rise during the first month after infection, can plateau for 3-6 months before returning to normal levels at 6-12 months. Individual responses can be variable requiring careful consideration of results. For this reason, the importance of paired serology to demonstrate increasing antibody levels is key in informing interpretation.

Department

Microbiology - Serology

Delphic Registration Code

STRP

Constituent Tests

• Streptococcal serology – Dnase, Blood

Synonyms

ASO
Dnase

Turnaround Time

7 days

Test Code

2449

Specimen Type

• Serum

Specimen Requirements

Tube/Container Type:

Preferred

• Serum (Red Cap)

Preferred if West Coast

• SST II (Gold Cap)

Acceptable

• SST II (Gold Cap)

Preferred Sample Volume (ml)

10.0

Minimum Sample Volume (ml)

5.0

No of Samples Required

1

Paediatric Specimen Requirements

Tube/Container Type:

Preferred

• Serum (Red Cap)

Acceptable

• Serum (Red Cap)

Preferred Sample Volume (ml)

5.0

Minimum Sample Volume (ml)

2.0

Additional Specimen Information

Serum only

Aliquot Instructions

Sample Type

• Serum

Minimum Volume (ml)

0.5

Transport to Lab

Chilled (2 - 8 degrees Celsius)
If overnight - Chilled (2 - 8 degrees Celsius)

Additional Referral/Aliquot Information

Preferred aliquot serum 2 mL

Interpretation

The cutoff values for serological evidence of Group A streptococcal disease vary dependent on the individual assay used by the laboratory and population based “Normals”.   Rising antibody levels of paired serology (2-4 weeks if not initially raised) provides greater information than testing on a single presentation sample.

In the use and interpretation of Strep A antibody testing for ARF  please refer to the Aotearoa New Zealand guidelines for the prevention , diagnosis, and management of Acute Rheumatic Fever and Rheumatic Heart Disease 2024 update, and the associated upper limits of normal for serum streptococcal antibody titres used in Aotearoa for acute rheumatic fever.

 

Interpretation in conjunction with Anti-Dnase B result  should also be taken into account.

Reference Intervals

Results are reported as International Units per mL:

For reference ranges please refer to the Aotearoa New Zealand guidelines for the prevention, diagnosis, and management of Acute Rheumatic Fever and Rheumatic Heart Disease 2024 update.

https://static.info.content.health.nz/docs/health-pros/topics/diseases-conditions/rheumatic-fever/Aotearoa-New-Zealand-Guidelines-for-the-Prevention-Diagnosis-and-Management-of-Acute-Rheumatic-Fever-and-Rheumatic-Heart-Disease-Summary-Guide.pdf

 

The ASO antibody kit used in our laboratory is The Beckman Coulter OSR6194 Anti-streptolysin O assay.

The manufacturers Reference intervals are:

Adults     ≤ 200 IU/mL
Children ≤ 150 IU/mL
*NOTE: Expected values may vary with age, sex, sample type, diet and geographical location. The transferability of the above Manufacturers ranges to our own unique geographical and population makeup may not apply. For diagnostic purposes, results should always be assessed in conjunction with the patient’s medical history, clinical examinations and other findings.  Please refer to the NZ guidelines above.

 

Test Method

Beckman Latex Turbidimetric Assay

Non-Funded Test Cost

$39.51 (Exclusive of GST)

Billing Code

2449

Onset date of illness desirable.

Contact Information

Enquiry Form