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The Test Sample
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 and targets the centromere, a component of the chromosomes (structures in the nucleus) found in all nucleated cells in our body 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: diffuse cutaneous systemic sclerosis that affects the entire body and limited cutaneous systemic sclerosis. These subsets of systemic sclerosis are defined on the basis of the extent of skin involvement. ACA is found in about 60-80% of people who have limited cutaneous scleroderma; only about 5% of patients with diffuse scleroderma have ACA.
Limited cutaneous scleroderma 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
ACA can be present in up to 95% of people who have CREST syndrome.
How is the sample collected for testing?
A blood sample is obtained by inserting a needle into a vein in the arm.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.