Ku for polymyositis/scleroderma overlap

Category: Rheumatology
Test Code: 050
Disease: Polymyositis/Scleroderma overlap, SLE
Methodology: Line Immunoassay
Reference Range: Qualitative
CPT Code: 84181
Schedule / Turnaround Time: Assay performed once every two weeks. Report availability is two weeks 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.


Ku antibodies have been found in 10% of patients with polymyositis/scleroderma overlap syndrome and in 10% of systemic lupus erythematosus patients. Patients with polymyositis/scleroderma overlap who are positive for Ku antibodies usually have a mild disease with a good prognosis.