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HelpTest Code NMS1 Necrotizing Myopathy Evaluation, Serum
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.
Useful For
Evaluating patients with suspected necrotizing autoimmune myopathy
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.
Method Name
SRPIS, SRPTS: Indirect Immunofluorescence Assay (IFA)
SRPBS: Immunoblot
HMGCR: Chemiluminescent Assay (CIA)
NSI1: Medical Interpretation
Reporting Name
Necrotizing Myopathy Evaluation, SSpecimen 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 |
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.
Clinical Reference
1. Kassardjian CD, Lennon VA, Alfugham NB, et al: Clinical Features and Treatment Outcomes of Necrotizing Autoimmune Myopathy. JAMA Neurol 2015 Sep;72(9):996-1003
2. Emslie-Smith A M, Engel A G: Necrotizing myopathy with pipestem capillaries, microvascular deposition of the complement membrane attack complex (MAC), and minimal cellular infiltration. Neurology 1991;41(6):936-939
3. Ramanathan S, Langguth D, Hardy T, et al: Clinical course and treatment of anti-HMGCR antibody-associated necrotizing autoimmune myopathy. Neurol Neuroimmunol Neuroinflamm 2015 June;2(3):e96
4. Allenbach Y, Keraen J, Bouvier AM, et al: High risk of cancer in autoimmune necrotizing myopathies: usefulness of myositis specific antibody. Brain 2016 Aug;139(Pt 8):2131-2135
5. Christopher-Stine L, Casciola-Rosen L, Hong G, et al: A novel autoantibody recognizing 200-kd and 100-kd proteins is associated with an immune-mediated necrotizing myopathy. Arthritis Rheum 2010 May;62(9):2757-2766
6. Mammen AL, Chung T, Christopher-Stine L, et al: Autoantibodies against 3-hydroxy-3-methylglutaryl-coenzyme A reductase in patients with statin-associated autoimmune myopathy. Arthritis Rheum 2011 Mar;63(3):713-721
7. Hengstman GJ, ter Laak HJ, Vree Egberts WT, et al: Anti-signal recognition particle autoantibodies: marker of a necrotising myopathy. Ann Rheum Dis 2006;65(12):1635-1638
8. Miller T, Al-Lozi MT, Lopate G, Pestronk A: Myopathy with antibodies to the signal recognition particle: clinical and pathological features. J Neurol Neurosurg Psychiatry 2002 Oct;73(4):420-428
9. Watanabe Y, Uruha A, Suzuki S, et al: Clinical features and prognosis in anti-SRP and anti-HMGCR necrotising myopathy. J Neurol Neurosurg Psychiatry 2016 Oct;87(10):1038-1044
Day(s) Performed
Tuesday, Thursday
Report Available
10 to 14 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Test 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 |
Reflex Tests
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| SRPBS | SRP Immunoblot, S | No | No |
| SRPTS | SRP IFA Titer, S | No | No |
Forms
If not ordering electronically, complete, print, and send a Neurology Specialty Testing Client Test Request (T732) with the specimen.