When you have symptoms such as fever, chest pain, fatigue and shortness of breath that suggest rheumatic fever, or symptoms such as accumulation of fluid (edema) and dark urine that are associated with glomerulonephritis, especially when you recently may have had a group A streptococcal infection that was not diagnosed and treated appropriately; may be done along with or following an antistreptolysin O (ASO) test
A blood sample drawn from a vein
Anti-DNase B (antideoxyribonuclease-B antibody) is one of the most common of several antibodies that are produced by the body's immune system in response to an infection with group A Streptococcus (strep infection). The anti-DNase B test measures the amount of this antibody in the blood. It is typically done with or following an antistreptolysin O (ASO) test, another test to detect antibody to a streptococcal antigen.
Group A Streptococcus (Streptococcus pyogenes), is the bacterium that causes strep throat and a variety of other infections, including skin infections (pyoderma, impetigo, cellulitis). In most cases, strep infections are diagnosed and successfully treated with antibiotics.
Sometimes a strep infection does not cause identifiable symptoms, goes untreated, or is treated ineffectively, and complications (sequelae), namely rheumatic fever and glomerulonephritis, can develop, especially in young children. These secondary conditions are uncommon in the U.S. because of routine strep testing and antibiotic treatment, but they do occur.
- Rheumatic fever is a delayed immune response in which the body produces antibodies directed against itself (autoimmune). This can cause serious damage to heart valves and lead to symptoms such as swelling and pain in several joints, heart inflammation (carditis), skin nodules, rapid, jerky movements (Sydenham chorea), and skin rash.
- Post-streptococcal glomerulonephritis, a condition affecting the kidneys, can develop a week or two after a strep infection. Your body produces antibodies to fight the strep infection, but these antibodies can eventually be deposited in the glomeruli, which are small, looping blood vessels within the kidneys that continually filter the blood. This can cause inflammation and kidney damage, affecting kidney function.
How is the test used?
The anti-DNase B test may be used to confirm that a recent strep infection with group A Streptococcus is the cause glomerulonephritis (a form of kidney disease) or rheumatic fever. The test may be used in conjunction with an ASO, another test used to detect prior strep infections.
Since complications resulting from strep infections have dropped in the U.S., so has use of the ASO test and anti-DNase B test.
When is it ordered?
The anti-DNase and ASO test are ordered when you have signs and symptoms that a healthcare practitioner suspects may be due to complications caused by a recent strep infection, including rheumatic fever and post-streptococcal glomerulonephritis.
Some signs and symptoms of rheumatic fever may include:
- 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 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
Some signs and symptoms of glomerulonephritis may include:
- Fatigue, decreased energy
- Producing less urine
- Bloody urine
- Joint pain
- Fluid accumulations and swelling (edema)
- High blood pressure
However, these symptoms can be seen in other conditions.
Anti-DNase B testing may be performed twice, with samples collected about two weeks apart, for acute and convalescent titers. This is done to determine if the antibody level is rising, falling, or remaining the same.
What does the test result mean?
Anti-DNase B and ASO test results may be interpreted together. Anti-DNase B and ASO antibodies are produced about a week to a month after a strep infection. The amount of anti-DNase B antibody (titer) peaks about 4 to 6 weeks after the illness and may remain elevated for several months. They typically remain elevated longer than ASO antibody titers.
Negative anti-DNase B and ASO tests or very low titers means that it is unlikely you had a recent strep infection. This is especially true if a sample taken 10 to 14 days later is also negative. Your signs and symptoms are likely due to a cause other than a recent strep infection.
A small percentage (10-15%) of those who have a complication related to a recent strep infection will not have an elevated ASO titer. This is especially true with glomerulonephritis that develops after a skin strep infection. These people may, however, have an elevated anti-DNase B titer and/or an elevation in another streptococcal antibody such as an elevated antihyaluronidase titer.
Elevated or rising antibody titers of anti-DNase or ASO means that it is likely you had a recent strep infection.
If your have signs and symptoms of rheumatic fever or glomerulonephritis, an elevated anti-DNase B and/or ASO titer can help confirm the diagnosis.
Is there anything else I should know?
The anti-DNase B test may be ordered along with another streptococcal antibody test, such as an antihyaluronidase, especially if the ASO test is negative. A small percentage (10-15%) of people with a post-streptococcal complication will not have an elevated ASO but may have an elevated anti-DNase B or antihyaluronidase titer. This is especially true with glomerulonephritis linked to a recent skin strep infection.
Can an anti-DNase B or an ASO be used to diagnose strep throat?
No. A rapid strep test and/or throat culture are the best methods to diagnose strep throat. It is important that strep throat be promptly identified and treated to avoid complications and to avoid passing the infection on to others.
Can I develop rheumatic fever or glomerulonephritis at the same time as my strep throat?
If I am diagnosed with strep, will an anti-DNase B or ASO always be performed?
Like the rapid strep test, can the anti-DNase B test be performed in my doctor's office?