Antideoxyribonuclease-B Titer

Test Description

Deoxyribonuclease B is an antigen produced by group A streptococci. When the

body is confronted by this antigen, it produces antibodies against the antigen. The

antideoxyribonuclease-B test is designed to detect these antibodies. If the antibodies

are present, the person has had a streptococcal infection. The anti-DNase B

level increases after the person has recovered from the infection. This test is considered

more sensitive than the antistreptolysin-O (ASO) test. When both tests are

consistently performed on blood samples, 95% of the streptococcal infections can

be identified. The test is particularly useful in the diagnosis of rheumatic fever and

post-streptococcal glomerulonephritis, both sequelae of infections involving group-A

beta-hemolytic streptococci.

Normal Values

Adult:                                        <85 Todd U/mL

Child age 7 and older:               <170 Todd U/mL

Child younger than age7:          <60 Todd U/mL

Possible Meanings of Abnormal Values

Increased 

Acute rheumatic fever

Poststreptococcal glomerulonephritis

Pyodermic skin infection

Contributing Factors to Abnormal Values

• Hemolysis of the blood sample may alter test results.

• Drugs that may decrease results: antibiotics.

Interventions/Implications

Pretest 

• Explain to the patient the purpose of the test and the need for a blood sample to be drawn.

• No fasting is required before the test.

Procedure

• A 7-mL blood sample is drawn in a red-top collection tube.

• Gloves are worn throughout the procedure.

Posttest

• Apply pressure at venipuncture site. Apply dressing, periodically assessing for continued

  bleeding.

• Label the specimen and transport it to the laboratory.

• Report abnormal findings to the primary care provider

Clinical alert                

For the most reliable results, the Anti-DNase-B test should be performed in conjunction

with the ASO test.

Antidiuretic