Mixed connective tissue disease (MTCD) is an unusual systemic inflammatory rheumatic disease. MCTD could be a specific subset of the wider category of rheumatic “overlap syndromes”, a term used to describe when a patient has features of over than one classic inflammatory rheumatic disease. These classic rheumatic diseases consist of systemic lupus erythematosus, polymyositis, scleroderma, and rheumatoid arthritis.
- Routine tests:
- CBC
- ESR
- CRP
- Routine blood chemistry
- Urinalysis
- Immunology tests
- Autoantibodies:
- ANA
- RNP- Positive in 95-100% MCTD patients
- dsDNA, Sm, Ribosomal-P- present in MCTD patients
- Other tests:
- Immunoglobulins- hypergammaglobulinemia
- Rheumatoid factor- often positive
- Anti-CCP- often positive
Algorithm
References
- Sharp GC, Irvin WS, Tan EM, et al. Mixed connective tissue disease–an apparently distinct rheumatic disease syndrome associated with a specific antibody to an Extractable Nuclear Antigen (ENA). Am J Med 1972; 52:148–59.
- Brouwers MC, Kho ME, Browman GP, et al. AGREE II: advancing guideline development, reporting and evaluation in health care. Can Med Assoc J 2010;182: E839–42.
- Benito-Garcia E, Schur PH, Lahita R, et al. Guidelines for immunologic laboratory testing in the rheumatic diseases: anti-Sm and anti-RNP antibody tests. Arthritis Rheum 2004; 51:1030–44.
