Mixed Connective-Tissue Disease (MCTD) Workup

Updated: Dec 22, 2022
  • Author: Eric L Greidinger, MD; Chief Editor: Herbert S Diamond, MD  more...
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Laboratory Studies

Laboratory studies used in the workup for mixed connective-tissue disorder (MCTD) are as follows:

  • Complete blood cell count (CBC)
  • Urinalysis
  • Routine blood chemistry
  • Indicators of acute phase response (erythrocyte sedimentation rate [ESR] or C-reactive protein [CRP])
  • Muscle enzymes if myositis is suspected clinically
  • Antinuclear antibodies
  • Anti–U1-ribonucleoprotein (RNP) antibodies
  • Amylase and lipase - To assess for pancreatitis if clinically indicated
  • Serologic indicators of pulmonary hypertension (such as brain natriuretic peptide [BNP]) 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 but not specific.

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 typically absent
  • Scleroderma-specific antibodies, including anticentromere, anti–Scl-70 (topoisomerase), and anti–PM-1 (Pm-Scl), are typically absent
  • C3 and C4 complement levels are more likely to be depleted in lupus than in MCTD

Imaging Studies

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) [35]

  • 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

Chest radiograph in a patient with pulmonary hyper Chest radiograph in a patient with pulmonary hypertension reveals enlarged pulmonary arteries.

Other Tests

The following tests may be part of the workup for MCTD:

  • Pulmonary function testing is used to screen for declining diffusing capacity of lung for carbon monoxide (DLCO), possibly indicating pulmonary hypertension, [36]  or to assess lung volumes and forced vital capacity to screen for suspicion/progression of interstitial lung disease.
  • Electrocardiogram and/or cardiac enzymes is helpful to assess for myocardial ischemia and myocarditis.
  • Infection, stroke, or neuropsychiatric manifestations may be monitored with cerebrospinal fluid (CFS) analysis.
  • The six-minute walk can be helpful to assess for cardiopulmonary insufficiency, possibly indicating pulmonary hypertension. [37]
  • Right-sided heart catheterization is the criterion standard for confirming the diagnosis of pulmonary hypertension