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Stiff-Person Spectrum Disorders Evaluation, Serum (Sendout)

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General Information

Lab Name
Lab Code
1108
External Test Id
SPPS
Description

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 using serum specimens

Testing Algorithm:

  • If the indirect immunofluorescence assay (IFA) pattern suggests amphiphysin antibody, then amphiphysin immunoblot and amphiphysin IFA titer will be performed at an additional charge.
  • If the dipeptidyl-peptidase-like protein-6 (DPPX) cell bound assay is positive, then DPPX antibody IFA titer will be performed at an additional charge.

Patient Preparation: 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.

Ordering Requirements: Laboratory Medicine Resident approval is required.

Ordering Guidance: GAD65 Ab Assay (Sendout) [RGD65] is the recommended first-line test for Stiff-Person Syndrome. If panel testing is desired after a negative GAD65 Antibody result, submit a LADDON (Lab Add On) request for OLTG #1108/Mayo Test SPPS and specify that testing should be added to the sample at Mayo Clinic Laboratories. Specimens are stored at Mayo for up to 28 days.

References
Synonyms
Amphiphysin Antibody, DPPX Antibody CBA, GAD65 Antibody Assay, Glycine Alpha1 LCBA, PERM, Progressive enephalomyelitis, Spinal interneuronitis, SPPS, Stiff-man
Components

Interpretation

Guidelines
Method

Panel and reflex tests include the following methods: Indirect Immunofluorescence Assay (IFA), Cell-Binding Assay (CBA), Radioimmunoassay (RIA), Live Cell-Binding Assay (LCBA), Immunoblot (IB)

Reference Range
Ref. Range Notes

Reference Ranges:

Amphiphysin Antibody: Negative
DPPX Antibody CBA: Negative
GAD65 Antibody Assay: < or =0.02 nmol/L
Glycine Alpha1 LCBA: Negative

Note: Includes reference values for panel tests only.

Interpretation: 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.

Interferences and Limitations

Cautions: 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.

References

Ordering & Collection

Specimen Type
Blood
Collection

6 mL blood in RED top tube

Also Accepted: GOLD SST

Approval Required
Laboratory Medicine Resident (LMR) approval is required.
Handling Instructions

Outside Laboratories: Centrifuge sample and transfer serum to a separate plastic vial. Refrigerate serum while awaiting shipment. Ship sample with a cold pack.

Stability: Refrigerated (preferred): 28 days; Frozen: 28 days; Ambient: 72 hours.

Reject Due To: Gross hemolysis, lipemia, or icterus.

Quantity
Requested: 2 mL serum
Minimum: 1 mL serum

Processing

Receiving Instructions

Centrifuge sample and transfer serum to a separate plastic vial.

Login: SEND1-;REFRIG

  • RSNDT1: MAYO
  • RSTYP1: SRM
  • RTSRQ1: ;Stiff Person Spectrum Disorders Evaluation, Serum (Mayo Test SPPS)

Sendouts:

  • Order Mayo Test: SPPS

Stability: Refrigerated (preferred): 28 days; Frozen: 28 days; Ambient: 72 hours.

Reject Due To: Gross hemolysis, lipemia, or icterus.

Misc Sendout

Performance

Lab Department
Frequency
Performed: Monday through Sunday. Report Available: 5-10 days from sample receipt at Mayo Clinic Labs.
Available STAT?
No
Performing Location(s)
Sendout Mayo Clinic Laboratories
800-533-1710

200 First Street Southwest
Rochester, MN 55901

Billing & Coding