The antinuclear antibody (ANA) blood test identifies a specific protein in the bloodstream. It can help guide the diagnosis of certain conditions. Doctors often use it to rule out lupus or other autoimmune disorders.
The immune system produces antibodies that fight unwanted invaders to keep the body healthy. However, this network of cells, organs, and proteins sometimes incorrectly identifies the person’s own tissue as a threat and attacks it.
A doctor can test for ANAs in the blood. If these proteins are present, a person may have an autoimmune disease, such as lupus.
When using the ANA test to make a diagnosis, a doctor will consider a range of other factors, including the person’s medical history and symptoms.
In this article, we describe what to expect when receiving the ANA blood test and explain when the test is necessary.
This test measures the levels of ANAs in the blood, and a positive result can point to an autoimmune disease.
What are ANAs?
In general, antibodies are proteins that instruct immune cells to target and attack foreign cells and particles.
The cells of the immune system usually respond to antibodies, and this allows them to distinguish between particles that belong to the body and others that may cause harm.
However, some antibodies trigger the immune system to attack the body’s own tissue. These are called autoantibodies, and they are the basis of autoimmune diseases.
ANAs are antibodies that cause the immune system to attack the nuclei, or processing centers, of the body’s own cells and tissues. The nucleus of a cell contains its genetic material.
ANAs and autoimmune conditions
A person with a high level of ANAs
- systemic lupus erythematosus, or lupus
- Sjögren’s disease, in which the immune system attacks the salivary and tear glands, leading to dryness in the mouth and eyes
- systemic sclerosis, or scleroderma, which causes thickening of the skin alongside other potential issues
- mixed connective tissue disease, such as lupus or systemic sclerosis, in which a number of autoimmune problems occur together
- Raynaud’s phenomenon, in which the autoimmune process affects the blood flow and causes the extremities, such as the fingers, to change color in cold temperatures
An ANA test will usually give a positive result in a person with lupus, which is an autoimmune disease. The American College of Rheumatology reports that more than 95% of people with lupus test positive for ANA. As a result, doctors consider the test to be highly sensitive for this condition, and a negative ANA test is often confirmation that an individual does not have lupus.
However, not everyone with a positive ANA result has lupus. A person can have ANAs in the bloodstream without having an autoimmune disorder.
Therefore, as part of the diagnosis, a doctor will also need to consider a person’s symptoms and perform a physical examination.
The symptoms of lupus vary in type and severity, and they can be intermittent.
A person can experience symptoms that
- Muscle and joint pain: This pain most commonly affects the:
- upper arms
- Fatigue: Lupus often causes extreme tiredness and a loss of energy.
- Memory problems: People with lupus may experience forgetfulness and confusion.
- Skin rash: The rash that characterizes lupus usually affects the face, hands, and feet.
On the face, the rash often appears across the nose and cheeks. Medical professionals refer to this as a butterfly rash. It can present differently on black skin.
A lupus rash is often sensitive to the sun, so taking protective steps, such as applying sunscreen, is important.
A healthcare professional will take a blood sample using a needle and syringe or vial, typically via a vein in the arm. The needle puncture will usually be quick and only mildly painful, but it may leave a tiny wound.
A person will likely be able to return to their regular activities after giving the blood sample.
Getting ready for the ANA blood test
A person does not need to prepare, such as by avoiding food or drink, before giving the blood sample. However, it is important to speak with the doctor to confirm this ahead of time. The doctor may also have requested other blood tests that do require fasting.
Several medications can affect ANA levels. It is important to make the healthcare professional aware of any current medications before they take the sample.
The steps that follow a positive result depend on the person’s overall health. Their symptoms will help determine the cause of the ANA levels.
If the result accompanies a set of symptoms and a medical history that confirm an autoimmune disorder diagnosis, the doctor will advise the individual about how to manage the condition.
Lupus: Next steps
If the ANA test confirms a diagnosis of lupus, drug treatments may include pain relievers called nonsteroidal anti-inflammatory drugs. Examples of these include ibuprofen and naproxen.
Other medications that can help manage lupus symptoms
- hydroxychloroquine or chloroquine, for reducing inflammation
- corticosteroids, which can also lessen inflammation
- immunosuppressive drugs
People with lupus can have full, active lives with the appropriate medical management.
The ANA test is a highly sensitive but nonspecific test that can help rule out autoimmune conditions such as lupus.
A doctor administers the test in a very similar way to other blood tests, and the person does not need to make special preparations.
Although doctors often use the test to confirm a diagnosis of lupus, it can sometimes provide false-negative or false-positive results.
Confirming any diagnosis requires a doctor to gain a thorough understanding of a person’s symptoms and medical history.