Stiff-Person Spectrum Disorders Evaluation, including Progressive Encephalomyelitis with Rigidity and Myoclonus, Serum
Test Mnemonic
SPSDEV
CPT Codes
- 86341 - QTY (1)
- 86255 - QTY (2)
- 0431U - QTY (1)
Includes
- Amphiphysin Ab
- GAD65 Ab Assay
- DPPX Ab CBA
- Glycine Alpha1 LCBA
- Stiff-Person/PERM Interp
- IFA Notes
Performing Laboratory
Mayo Clinic Dpt of Lab Med & Pathology
Specimen Requirements
| Volume | Type | Container | Collect Temperature | Transport Temperature | Special Instructions |
|---|---|---|---|---|---|
| 2 mL | Serum | No additive (Red) | Refrigerated | This test should not be requested in patients who have recently received radioisotopes (refer to Special Information). Centrifuge and transfer serum to standard aliquot tube. |
Alternate Specimen Requirements
| Volume | Type | Container | Collect Temperature | Transport Temperature | Special Instructions |
|---|---|---|---|---|---|
| 2 mL | Serum | SST (Gold) | Refrigerated | This test should not be requested in patients who have recently received radioisotopes (refer to Special Information). Centrifuge and transfer serum to standard aliquot tube. |
Minimum Specimen Requirements
| Volume | Type | Container | Collect Temperature | Transport Temperature | Special Instructions |
|---|---|---|---|---|---|
| 1 mL |
Stability
| Environmental Condition | Description |
|---|---|
| Refrigerated | 28 days |
| Frozen | 28 days |
| Ambient | 72 hours |
Days Performed
Sun - Sat
Turnaround Time
6 - 11 days
Methodology
| Name | Description |
|---|---|
| Cell Binding Assay (CBA) | |
| Indirect Immunofluorescence Assay (IFA) | |
| Radioimmunoassay (RIA) | |
| Live Cell-Binding Assay (LCBA) |
Reference Range
| GAD65 Antibody | |||||
|---|---|---|---|---|---|
| Sex | Age From | Age To | Type | Range | Range Unit |
| < or = 0.02 nmol/L |
Special Info
Reflex Algorithm: Each reflex test performed incurs additional charge. If client requests or if the indirect immunofluorescence assay (IFA) pattern suggests amphiphysin antibody, then amphiphysin immunoblot and amphiphysin IFA titer will be performed. If the dipeptidyl-peptidase-like protein-6 (DPPX) cell bound assay is positive, then DPPX antibody IFA titer will be performed. This test should not be requested for patients who have recently received radioisotopes, therapeutically or diagnostically, because of potential assay interference. The specific waiting period before specimen collection will depend on the isotope administered, the dose given, and the clearance rate in the individual patient. Specimens will be screened for radioactivity prior to analysis. Radioactive specimens received in the laboratory will be held 1 week and assayed if sufficiently decayed or canceled if radioactivity remains. Grossly hemolyzed, lipemic or icteric specimens will be rejected. This test is New York state approved.
Clinical Info
This test is useful for evaluating patients with suspected stiff-person syndrome (classical or focal forms, such as stiff-limb or stiff-trunk) and progressive encephalomyelitis with rigidity and myoclonus. Seropositivity supports the clinical diagnosis of stiff-person spectrum disorder (classical stiff-person, stiff-limb, stiff-trunk, or progressive encephalomyelitis with rigidity and myoclonus). A paraneoplastic basis should be considered. Negative results do not exclude the diagnosis of stiff-person spectrum disorder or progressive encephalomyelitis with rigidity and myoclonus (PERM). Glutamic acid decarboxylase 65 (GAD65) antibody positive values below 20 nmol/L should be interpreted with caution. Lower values are encountered in 8% of the general population. However, GAD65 autoimmunity (any antibody value) is associated with other autoimmune diseases that can cause neurological symptoms, including type 1 diabetes, pernicious anemia, hypothyroidism, and adrenal insufficiency.