Necrotizing Myopathy Evaluation, Serum
Use
Necrotizing autoimmune myopathy (NAM) is strongly associated with autoantibodies to either signal recognition protein (SRP) or 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR). The test aids in evaluating patients with suspected NAM by identifying these autoantibodies early, enabling timely initiation of aggressive immune treatments. NAM may manifest with proximal limb muscle weakness and elevated serum creatine kinase levels. The presence of these autoantibodies may indicate a paraneoplastic disorder and should also prompt assessment for an underlying malignancy.
Special Instructions
Before ordering this test, assess the probability of the patient having immune-mediated necrotizing myopathy using the Immune-mediated necrotizing myopathy calculator. Provide relevant clinical information and complete the Neurology Specialty Testing Client Test Request form if not ordering electronically.
Limitations
Antibodies against 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) or signal recognition protein (SRP) may also be detected in cases of polymyositis, dermatomyositis, or other autoimmune disorders. Such serology results should be interpreted alongside muscle biopsy findings and within the patient's clinical context, as other conditions could mimic or have overlapping symptoms with NAM.
New York Approved
Methodology
Immunoassay
Biomarkers
LOINC Codes
- 97561-5
- 69048-7
- 97562-3
- 93493-5
Result Turnaround Time
10-14 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
3 mL
Minimum Volume
2 mL
Container
Plastic vial
Collection Instructions
Centrifuge within 2 hours of collection and aliquot serum into a plastic vial.
Causes for Rejection
Gross hemolysis, gross lipemia, gross icterus
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 72 hours |
| Refrigerated | 28 days |
| Frozen | 28 days |