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HelpTest Code NMS1 Necrotizing Myopathy Evaluation, Serum
Reporting Name
Necrotizing Myopathy Evaluation, SPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Useful For
Evaluating patients with suspected necrotizing autoimmune myopathy
Method Name
SRPIS, SRPTS: Indirect Immunofluorescence Assay (IFA)
SRPBS: Immunoblot
HMGCR: Chemiluminescent Assay (CIA)
NSI1: Medical Interpretation
Ordering Guidance
Before ordering this test, assess the probability of the patient having immune-mediated necrotizing myopathy by using the Immune-mediated necrotizing myopathy calculator.
Necessary Information
Provide the following information:
-Relevant clinical information
-Ordering provider name, phone number, mailing address, and e-mail address
Specimen Required
Collection Container/Tube:
Preferred: Red top
Acceptable: Serum gel
Submission Container/Tube: Plastic vial
Specimen Volume: 3 mL
Collection Instructions: Centrifuge within 2 hours of collection and aliquot serum into a plastic vial.
Specimen Type
SerumSpecimen Minimum Volume
2 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 28 days | |
| Frozen | 28 days | ||
| Ambient | 72 hours |
Reject Due To
| Gross hemolysis | Reject |
| Gross lipemia | Reject |
| Gross icterus | Reject |
Reference Values
3-Hydroxy-3-Methylglutaryl Coenzyme-A (HMG-CoA) Reductase:
<20.0 CU
Signal Recognition Particle Antibody Screen:
Negative
Signal Recognition Particle Antibody:
Negative
Signal Recognition Particle Antibody, Titer:
<1:240
Interpretation
Seropositivity for 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) or signal recognition protein (SRP) autoantibodies supports the clinical diagnosis of necrotizing autoimmune myopathy (NAM). A paraneoplastic basis should be considered, according to age, sex, and other risk factors. In cases of NAM, immune therapy is required and often multiple simultaneously utilized immunotherapies are needed to successfully treat patients.
Day(s) Performed
Tuesday, Thursday
Report Available
10 to 14 daysTest Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
86255
82397
86256 (if appropriate)
84182 (if appropriate)
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| NMS1 | Necrotizing Myopathy Evaluation, S | 97561-5 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 607414 | HMG-CoA Reductase Ab, S | 93493-5 |
| 603543 | Necrotizing Myopathy Interp, S | 69048-7 |
| 603540 | SRP IFA Screen, S | 97562-3 |
Forms
If not ordering electronically, complete, print, and send a Neurology Specialty Testing Client Test Request (T732) with the specimen.
Profile Information
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| NSI1 | Necrotizing Myopathy Interp, S | No | Yes |
| HMGCR | HMG-CoA Reductase Ab, S | Yes | Yes |
| SRPIS | SRP IFA Screen, S | No | Yes |
Testing Algorithm
A thorough understanding of a patient’s history, along with clinical examination and laboratory testing, are needed for a clinico-sero-pathological diagnosis of immune-mediated necrotizing myopathy (IMNM). To assess the probability of your patient having IMNM, see the Immune-mediated necrotizing myopathy calculator.
This focused algorithmic test is designed to achieve high sensitivity for identification of antibodies specific for necrotizing autoimmune myopathy (HMGCOA-IgG and SRP-IgG). This test is unique in the market by having an initial screen for signal recognition particle (SRP) antibodies performed using tissue indirect immunofluorescence, which increases clinical sensitivity as compared to SRP immunoblot methodologies.
If the indirect immunofluorescence assay (IFA) pattern suggests signal recognition particle (SRP) antibody, then the SRP IFA titer and SRP54 immunoblot will be performed at an additional charge.
Reflex Tests
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| SRPBS | SRP Immunoblot, S | No | No |
| SRPTS | SRP IFA Titer, S | No | No |