Category: Rheumatology
Test Code: 043
Disease: Antibodies to Extractable Nuclear (ENA) & Cytoplasmic Antigens
Methodology: ELISA
Reference Range: Negative: <50 ; Positive: ≥50
Units: EU/ml
CPT Code: 86235
Schedule / Turnaround Time: Assay performed once per week. Report availability is within one week from the time of specimen receipt.
Specimen Requirements:

Specimen need not be refrigerated or frozen. Collect 2-3 ml of blood in a red top or serum separator tube. If possible, separate serum from clot and place into white tube provided with Immco Diagnostics’ collection kits. If separation facilities are not available, the blood can be sent in the tube used for collection.

Sample Stability:

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


Antibodies to Sm occur in approximately 30-40% of systemic lupus erythematosus (SLE) patients. They are rare in other systemic connective tissue diseases and if present, indicate either overlap of disease or patients that have not yet fulfilled the American Rheumatology Assocation criteria for SLE.