An autoimmune disease is a condition in which the body’s immune system mistakenly attacks healthy cells. This umbrella term encompasses a diverse group of diseases and disorders, which may affect any number of the body’s organs, tissues, and systems. Some of the most common autoimmune diseases include:
- Rheumatoid arthritis (RA)
- Type 1 diabetes
- Multiple sclerosis (MS)
- Hashimoto’s thyroiditis
- Celiac disease
The symptoms associated with these diseases can vary greatly, but often include fatigue, achiness, joint pain, swelling, skin rashes, low-grade fever, numbness, and dizziness.
Why are autoimmune diseases so difficult to diagnose?
Because symptoms tend to be quite nonspecific and can be linked to any number of conditions, diagnosing autoimmune diseases is notoriously difficult. Additionally, symptoms often flare and remit, meaning they are not always present or consistent.
Patients who suffer from one autoimmune disease are also more likely to suffer from multiple autoimmune conditions, which further complicates the diagnostic process.
According to the Autoimmune Diseases Association, it takes on average 4.6 years and nearly 5 doctors for a patient to receive a correct autoimmune disease diagnosis. This can be an incredibly frustrating process for both the physician and the patient.
What is the Antinuclear Antibody Test (ANA)?
The antinuclear antibody test (ANA) is one of the first tests that physicians use when they suspect a patient may be showing symptoms of an autoimmune disorder. True to its name, this test screens for antinuclear antibodies, which are a category of antibodies that attack the healthy proteins within the cell nucleus.
A positive ANA test result means that antinuclear antibodies were found in the patient’s blood, and that they may have an autoimmune disease. Unfortunately, this test cannot identify specifically which disease the patient has, if they do in fact have one.
Around 20% of healthy people will test positive for antinuclear antibodies, even if they do not have an autoimmune disease. This is called a “false positive,” and is more likely to occur in women older than 65, or in patients suffering from infections like mononucleosis.
A negative ANA test means that no antinuclear antibodies were detected; however, it is still possible for someone with a negative test result to have an autoimmune disease. If the patient’s symptoms continue to linger, they may require additional autoimmune testing.
Even though the ANA test cannot provide concrete answers, it is still considered to be the best starting point for diagnosing autoimmune diseases. After completing this test, physicians can order additional tests to work towards an accurate diagnosis for the patient.
What are other common tests for autoimmune diseases?
Depending on the results of the ANA test and the symptoms expressed by the patient, physicians can place orders for additional tests. Some of the most common autoimmune tests include:
- Extractable nuclear antigen (ENA) panel—common follow-up to a positive ANA test
- Anti-double-stranded DNA (anti-dsDNA)—used to diagnose lupus
- Anticentromere antibody (ACA)—used to diagnose scleroderma
- Anti-RNP—used to diagnose a variety of systemic rheumatic diseases
- Anti-Sjogren’s SSA and SSB—used to diagnose Sjogren’s Syndrome
- Anti-CCP—used to diagnose rheumatoid arthritis
- Anti-Jo-1—used to diagnose various idiopathic inflammatory myopathies
If you suspect that you may be suffering from an autoimmune disease, the first step is to consult with your physician and schedule laboratory testing. Depending on your symptoms and initial test results, you may be referred to a specialist, such as a rheumatologist.