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What is a Centromere Antibodies test? 

Anti centromere antibodies (ACA), also known as centromere antibodies attack the centromere - a DNA region present in the nucleus of all cells except the red blood cells. These are a type of autoantibodies, meaning that they are mistakenly produced by the immune system to attack the body’s own tissues. 

Doctors order an ACA test to look for and measure the amount of ACA present in the blood. This test is mainly done to diagnose a form of scleroderma - a rare connective tissue disorder characterised by hardening of the skin. Scleroderma is of two types: 

  • Diffuse cutaneous systemic sclerosis 
  • Limited cutaneous systemic sclerosis

ACA is present in both types of scleroderma. Clinical studies show that ACAs are found in approximately 60%-80% of individuals with limited cutaneous scleroderma, but the percentage of ACA is far less in patients with diffuse scleroderma.

  1. Why is a Centromere Antibodies test performed?
  2. How do you prepare for a Centromere Antibodies test?
  3. How is a Centromere Antibodies test performed?
  4. What do Centromere Antibodies test results mean?

The typical symptoms of scleroderma are collectively known as CREST syndrome. These include:

  • Calcinosis (C) – deposition of calcium under the skin
  • Raynaud phenomenon (R) –fingers and toes turning white and blue in colour due to decreased blood flow
  • Oesophageal dysfunction (E) – difficulty in swallowing and acidity
  • Sclerodactyly (S) – skin appears tight, thick and shiny on the hands and fingers
  • Telangiectasia (T) – red spots on the skin

Your doctor will order an ACA test if he/she notices these symptoms. 

Other than diagnosing the syndrome, ACA test is also used to diagnose the following conditions when they are present individually: calcinosis (formation of calcium deposits in the soft tissues of the body), Raynaud phenomenon ( a condition in which certain areas in the body feel numb), and oesophageal dysfunction.

You do not require any preparation before this test.

A blood sample will be taken from a vein in your arm for this test. A doctor or lab technician will tie a tourniquet around your upper arm to help locate the right vein and then withdraw the required amount of blood with a sterile needle. 

Though it is a safe procedure, some risks associated with taking a blood sample include excessive bleeding at the site of blood withdrawal or accumulation of blood under the skin (haematoma). Some people also feel lightheaded after the test. Though most of these symptoms are temporary and subside on their own. If the discomfort persists, talk to a doctor as soon as possible

Typically, serum IgG is tested in ACA and the reference values are as follows. These values are applicable to all age groups.

  • Negative results if ACA <1.0 U
  • Positive results if ACA ≥ 1.0 U 

Normal results:

If the test results are negative, then it can be concluded that the presenting symptoms are due to another condition and not due to CREST syndrome. However, it is important to note that in a few individuals with scleroderma, ACAs may not be produced. 

Abnormal results:

If the test results are shown to be positive, the doctor will confirm the presence of CREST syndrome. He/she may then order further tests to establish the diagnosis. This is because ACAs can also be found in patients with primary biliary cirrhosis (PBC) and in individuals with rheumatoid arthritis

Hence, it is important to discuss the results with your doctor to get a clear and accurate interpretation. 

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational point of view and is in no way a substitute for medical advice by a qualified doctor.

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  1. Pagana KD,Pagana TJ. Mosby’s Diagnostic and Laboratory Test Reference. 10thed.2010. Mosby, Inc., Saint Louis, MO. Pp: 73.
  2. Oxford University Hospitals [internet]: NHS Foundation Trust. National Health Service. U.K., Centromere Antibodies
  3. Tan EM, Rodnan Gp, Garcia I, et al. Diversity of antinuclear antibodies in progressive systemic sclerosis. Anti centromere antibody and its relationship to CREST syndrome. Arthritis Rheum 1980, 23.617-625.
  4. Kallenberg CG. Anti-centromere antibodies (ACA. Clin Rheumatol. 1990 Mar;9(1 Suppl 1):136-9. PMID: 2203592.
  5. Gabrielli A et al. Scleroderma. New England Journal of Medicine. 2009;360(19):1989-2003. PMID: 19420368