Mixed Connective-Tissue Disease Workup
- Author: Eric L Greidinger, MD; Chief Editor: Herbert S Diamond, MD more...
Laboratory studies used in the workup for mixed connective-tissue disorder (MCTD) are as follows:
- Complete blood cell count (CBC)
- Routine blood chemistry
- Muscle enzymes if myositis is suspected clinically
- Antinuclear antibodies
- Anti–U1-ribonucleoprotein (RNP) antibodies
- Amylase and lipase - To assess for pancreatitis if clinically indicated
Antibody study results
High-titer speckled pattern fluorescent antinuclear antibody (FANA) is typical of MCTD. However, the presence of FANA is not specific to MCTD.
Anti-RNP antibodies are required for diagnosis of MCTD. Titers are typically high. The presence of anti–U1-70 kd is characteristic of MCTD.
MCTD can enter sustained remission later in the clinical course. Anti-RNP autoantibodies typically become undetectable in patients in remission.
Other immune studies
Further results are as follows:
- Antiphospholipid antibodies (including anticardiolipin antibodies and lupus anticoagulant) may be associated with pulmonary hypertension
- Rheumatoid factor is frequently detected
- Other lupus-specific antibodies (eg, anti–double-stranded DNA antibodies) are absent
- Scleroderma-specific antibodies, including anticentromere, anti–Scl-70 (topoisomerase), and anti–PM-1 (Pm-Scl), are absent
- C3 and C4 complement levels are more likely to be depleted in lupus than in MCTD
Imaging studies used in the workup of patients with MCTD include the following:
- Chest radiography - To assess for infiltrates, effusion, or cardiomegaly (see the image below)
- Echocardiography - In patients with effusion or chest pain, used to evaluate for pulmonary hypertension or valvular disease (exercise echocardiography may have increased sensitivity for identifying pulmonary hypertension)
- Ultrasonography/CT scanning - Used to evaluate abdominal pain (indicated for evidence of serositis, pancreatitis, or visceral perforation related to vasculitis)
- MRI - Used to assess neuropsychiatric signs or symptoms
See the list below:
- Pulmonary function testing - To screen for declining diffusing capacity of lung for carbon monoxide (DLCO), possibly indicating pulmonary hypertension
- ECG and/or cardiac enzymes - To assess for myocardial ischemia and myocarditis
- Cerebral spinal fluid (CFS) analysis - To monitor for infection, stroke, or neuropsychiatric manifestations
- Six-minute walk - To assess for cardiopulmonary insufficiency, possibly indicating pulmonary hypertension
Right-sided heart catheterization is the criterion standard for diagnosis of pulmonary hypertension.
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