Test Code #

044

CPT Code(s) #

86038, 86039, 86255, 86235 x5

Test Name

Mixed Connective Disease Panel (includes ANA, Sm, U1RNP, RNP70, Jo-1, Scl-70)

If Profile, Includes Tests:

N/A

Disease Name:

Systemic Connective Tissue Disease

Type of Study:

Serum Studies

Methodology:

Indirect Immunofluorescence (HEp-2) and Fluoroenzyme immunoassay (FEIA)

Substrate:

N/A

Reference Range:

ANA (Titer)
• Negative <40

Sm (U/mL)
• Negative <7
• Equivocal 7-10
• Positive >10

U1RNP (U/mL)
• Negative <5
• Equivocal 5-10
• Positive >10

RNP70 (U/mL)
• Negative <7
• Equivocal 7-10
• Positive >10

Jo-1 (U/mL)
• Negative <7
• Equivocal 7-10
• Positive >10

Scl-70 (U/mL)
• Negative <7
• Equivocal 7-10
• Positive >10

Units:

Titer, Units

Schedule:

Assay performed once per week. Report availability is within one week from the time of specimen receipt.

Specimen Requirements:

Collect 5-10 ml of blood in a red top or serum separator tube. If possible, separate serum from clot and place into red capped tube provided with Beutner Laboratories collection kits. If separation facilities are not available, the blood can be sent in the tube used for collection.

Sample Stability:

Stable at ambient temperature during shipment. If sample is stored prior to shipment, it is stable refrigerated (2-8ºC) up to five days and frozen (-20ºC or lower) up to one year.

Clinical Relevance:

MCTD is defined by a combination of clinical and serologic features. Patients present with overlapping features of SLE, scleroderma, and polymyositis. The most common clinical manifestations of mixed connective disease are Raynaud's phenomenon, arthralgias, swollen joints, esophageal dysfunction, muscle weakness and the presence of anti-ribonucleoprotein (RNP) antibodies. The disease can be serious with development of pulmonary, kidney, cardiovascular, gastrointestinal and central nervous system manifestations. Serologic findings include a very high ANA titer, often with a speckled pattern, and antibodies directed against a specific ribonuclease-sensitive extractable nuclear antigen, U1RNP. U1RNP antibodies are present in >80% of patients with MCTD. Antibodies to other nuclear antigens have been found in MCTD. Antibodies to dsDNA and Sm are infrequent in patients with MCTD, these are found in 0-8% of patients with MCTD. Anti-Ro antibodies are positive in 13%, Scl-70 and Jo-1 in 7% of patients. Up to 70% of patients will have a positive rheumatoid factor.

References:

Ortega-Hernandez OD, Shoenfeld Y. Mixed connective tissue disease: an overview of clinical manifestations, diagnosis and treatment. Best Pract Res Clin Rheumatol. 2012 Feb;26(1):61-72.

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