At a Glance

Why Get Tested?

To detect the presence of anticentromere antibodies; to help diagnose limited cutaneous scleroderma, a subtype of scleroderma, also known as systemic sclerosis, a rare connective tissue disorder that is generally classified as an autoimmune disorder

When To Get Tested?

When you have one or more symptoms that suggest CREST syndrome; when you have a positive result on an antinuclear antibody (ANA) test

Sample Required?

A blood sample drawn from a vein in your arm

Test Preparation Needed?

None

What is being tested?

The anticentromere antibody (ACA) is an autoantibody, a protein produced by the immune system that mistakenly targets the body’s own tissues. ACA is one of several antinuclear antibodies. It targets the centromere, a component of the chromosomes (structures in the nucleus) found in all nucleated cells in our bodies except red blood cells. The ACA test detects and measures the amount of anticentromere antibody found in blood to help diagnose a form of scleroderma.

Scleroderma (also known as systemic sclerosis) is a group of rare connective tissue disorders. There are two distinct subtypes of systemic sclerosis that are defined based on how much of the skin is affected:

  • Diffuse cutaneous systemic sclerosis that affects the entire body
  • Limited cutaneous systemic sclerosis that is typically associated with one or more symptoms that are known collectively as CREST syndrome

CREST syndrome symptoms include:

  • Calcinosis – calcium deposits under the skin
  • Raynaud phenomenon – episodes of decreased blood flow to fingers and toes, causing them to turn white and blue
  • Esophageal dysfunction – difficulty swallowing, acid reflux, and heartburn
  • Sclerodactyly – tight, thick, shiny skin on the hands and fingers
  • Telangiectasia – red spots on skin due to swollen capillaries

Other signs that may be considered in scleroderma include fingertip lesions, abnormal capillaries in the skin just below the fingernails, high blood pressure in the lungs (pulmonary arterial hypertension) and/or scarring of the lungs (interstitial lung disease).

ACA is found in about 60-80% of people who have limited cutaneous scleroderma while only about 5% of patients with diffuse scleroderma have ACA. ACA can be present in up to 95% of people who have CREST syndrome.

Common Questions

How is the test used?

The anticentromere antibody (ACA) test is primarily ordered to help diagnose the autoimmune disorder limited cutaneous scleroderma, a form of systemic scleroderma, and CREST syndrome. The test may be used to distinguish between this and other conditions with similar symptoms.

An ACA test may be ordered along with other tests for autoantibodies, including ANA (antinuclear antibody) testing. ACA testing may be used to provide your healthcare practitioner with additional information if an ANA test is positive, especially if the test produces a certain pattern characteristic of particular antibodies.

An ACA test may be ordered along with a Scl-70 (anti-topoisomerase I) test. Scl-70 is another autoantibody that may be present with scleroderma. An anti-RNA polymerase III autoantibody (ARA) test may also be ordered in the diagnosis of systemic sclerosis. These autoimmune antibody tests could be performed as part of an Extractable Nuclear Antigen (ENA) antibody panel, or other antibody panels for autoimmune disorders and/or systemic sclerosis.

When is it ordered?

The ACA test may be ordered when you have a positive result on an ANA test and/or one or more of the symptoms associated with CREST. These symptoms include:

  • Calcinosis – calcium deposits under the skin
  • Raynaud phenomenon – episodes of decreased blood flow to fingers and toes, causing them to turn white and blue
  • Esophageal dysfunction – difficulty swallowing, acid reflux, and heartburn
  • Sclerodactyly – tight, thick, shiny skin on the hands and fingers
  • Telangiectasia – red spots on skin due to swollen capillaries

What does the test result mean?

If a your ACA result is positive, indicating you have anti-centromere antibodies in your blood, and you have symptoms of CREST, then it is likely that you have limited cutaneous scleroderma. ACA is found in about 60-80% of people who have limited cutaneous scleroderma and can be present in up to 95% of those who have CREST syndrome. Around 5-7% of ACA positive patients develop diffuse cutaneous scleroderma.

If your ACA result is negative, then it is likely that your symptoms are due to another condition. However, it is possible, though rare, that you have limited cutaneous scleroderma and do not produce anticentromere antibodies, resulting in a negative ACA test.

Is there anything else I should know?

ACA can be positive in some other autoimmune disorders, such as lupus, rheumatoid arthritis, or primary biliary cirrhosis.

Typically, only people who have CREST symptoms are tested for ACA. However, some people may be positive for ACA prior to the development of these symptoms and ACA may be performed in conjunction with testing for other autoimmune disorders such as ANA testing.

The amount of ACA present does not, in general, correlate to the severity of signs and symptoms.

What other lab tests may be done?

In addition to ACA testing, other laboratory tests may be ordered to monitor your health status, including:

Is there anything I can do to decrease my anticentromere antibody level?

No, it does not respond to lifestyle changes.

Will my anticentromere antibody ever go away?

Concentrations of ACA in the blood may vary over time, but once you have developed ACA, you will continue to produce them for life.

Can anticentromere testing be done at my healthcare practitioner's office?

No. ACA testing requires collection of a blood sample by a trained medical professional. The testing itself requires specialized equipment and trained medical laboratory personnel. It is not offered by every laboratory and usually is performed by a reference laboratory.

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