The SCL-70 blood test was developed to detect a specific enzyme that acts as an antibody to the presence of scleroderma. This connective tissue disorder and similar diseases create SCL-70 antibodies that can be detected. Along with other tests, a medical provider can determine whether or not systemic sclerosis exists.
Not everyone will receive the SCL-70 blood test if scleroderma is suspected. People who do not have antinuclear antibodies will have results that are classified as useful. This blood test also has a 40% failure rate when it comes to detecting connective tissue disorders. A positive test result, however, is generally an indication that a scleroderma diagnosis is forthcoming.
What Do My Test Results Mean?
Unlike other blood tests that can generate false positives, the SCL-70 blood test is very accurate when it comes to a positive result. The antibodies are very specific to scleroderma and are very rarely present with other diseases or disorders. There are no known published cases of SCL-70 antibodies being associated with other conditions.
A medical provider will typically interview a patient with suspected scleroderma to discuss their physical symptoms. An examination will also be conducted and certain blood tests may be ordered immediately before the SCL-70 test. The examination routine typically follows what has become known as the CREST diagnosis. Here is what the acronym represents.
- Calcium that leaves deposits underneath the skin. There may or may not be the symptoms of calcium toxicity with this specific symptom.
- Raynaud phenomenon which causes the fingers and toes to become cold, turn white or blue, and even feel numb. This phenomenon can be triggered by virtually anything and is associated with other conditions as well.
- Esophageal dysfunction which may include heart burn, acid reflux issues, or problems swallowing.
- Sclerodactyly, which is a medical term for skin that is thick, shiny, and tight along the hands and fingers.
- Telangiectasia, which is a medical term for red spots that form on the skin because capillaries underneath are abnormally swollen.
Why is the CREST examination methodology practiced before the SCL-70 blood test? It is because when these symptoms are present, the test results can be up to 95% accurate in determining whether or not scleroderma is present. An ACA blood test may also be ordered to confirm the results. If there are more CREST symptoms being experienced, there is a better chance that scleroderma may be present.
When the symptoms of scleroderma are present, the SCL-70 test is negative, but the ACA blood test is positive, then a different autoimmune disorder may be affecting the body. Lupus is the most common issue associated with this set of test results, but primary biliary cirrhosis or rheumatoid arthritis may also be present.
Here’s What You Need to Know About SCL-70
Unlike other conditions, there are not any lifestyle changes that will generally affect the SCL-70 blood test results. Once antibodies are being produced, they will continue to be produced over the person’s lifetime. The concentrations of the antibodies may change over time, but in general, once a positive test is received, it will continue to happen.
Most people will never need to have this blood test ordered. Scleroderma is a rather rare disease. Because of this, the blood test requires specific equipment and training that may not be available at a local medical provider. Most blood samples are taken to a reference laboratory for results, which means it can be 3-5 business days before hearing back about a specific test.
All it takes is for one of the CREST symptoms to be present for a medical provider to consider ordering the SCL-70 blood test. Other tests may be ordered before it or a complete ENA panel may be requested instead. No test preparation is needed, but a diagnosis may not occur unless the test results and CREST symptoms are able to match themselves up.
The SCL-70 blood test is a specific test that is designed to produce specific results. Although it may not always be accurate and provide a negative result when scleroderma is present, a positive result can provide a diagnosis of this connective tissue disorder so that a treatment plan can begin.
If you are experiencing any of the CREST symptoms, then schedule an appointment with your medical provider right away. Take this guide with you to discuss what your testing and treatment options may be based on your unique medical history so that you can understand what the results will be when they come in.