Anti-DNase B blood test
Strep throat - anti-DNase B test; Antideoxyribonuclease B titer; ADN-B test
Anti-DNase B is a blood test to look for antibodies to a substance (protein) produced by group A streptococcus. This is the bacteria that cause strep throat.
When used together with the ASO titer test, more than 90% of past streptococcal infections can be identified.
Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. Preparation may vary depending on the specific test.
How the Test is Performed
How to Prepare for the Test
No special preparation is necessary.
How the Test will Feel
When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging sensation. Afterward, there may be some throbbing or a slight bruise. This soon goes away.
Why the Test is Performed
This test is most often done to tell if you have previously had a strep infection and if you might have rheumatic fever or kidney problems (glomerulonephritis) due to that infection.
Normal Results
A negative test is normal. Some people have low concentrations of antibodies, but they have not had a recent strep infection. Therefore, normal values in different age groups are:
- Adults: less than 85 units/milliliter (mL)
- School-age children: less than 170 units/mL
- Preschool children: less than 60 units/mL
Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different specimens. Talk to your health care provider about the meaning of your specific test results.
What Abnormal Results Mean
Increased levels of DNase B levels indicate exposure to group A streptococcus.
Risks
There is little risk involved with having your blood taken. Veins and arteries vary in size from one person to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.
Other risks:
- Excessive bleeding
- Fainting or feeling lightheaded
- Multiple punctures to locate veins
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
Considerations
References
Bryant AE, Stevens DL. Streptococcus pyogenes. In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 197.
Version Info
Last reviewed on: 5/19/2023
Reviewed by: Jatin M. Vyas, MD, PhD, Associate Professor in Medicine, Harvard Medical School; Associate in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
