American Board of Internal Medicine (ABIM) Certification Practice Exam

Which laboratory marker is associated with CREST syndrome?

1. Smooth muscle antibody

2. Anticentromere antibody

3. Nuclear antibody

4. Rheumatoid factor

The correct answer is: Anticentromere antibody

CREST syndrome is a limited form of systemic sclerosis (scleroderma) characterized by the presence of specific clinical features: Calcinosis, Raynaud's phenomenon, Esophageal dysmotility, Sclerodactyly, and Telangiectasia. The laboratory marker that is most commonly associated with this condition is the anticentromere antibody. Anticentromere antibodies are specific to CREST syndrome and help in distinguishing it from other forms of scleroderma. The presence of these autoantibodies is often found in patients with limited scleroderma, which correlates with the milder features seen in CREST. In contrast, smooth muscle antibodies are more associated with autoimmune hepatitis and primary biliary cholangitis, nuclear antibodies indicate a broader category of autoimmune diseases such as lupus, and rheumatoid factor is typically linked to rheumatoid arthritis. Therefore, the significant relationship between anticentromere antibodies and CREST syndrome makes this the correct choice in identifying a laboratory marker associated with the condition.