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Test Code NFSMI Neurofilament (SMI31) Immunostain, Technical Component Only

Advisory Information

This test includes only technical performance of the stain (no pathologist interpretation is performed). If diagnostic consultation by a pathologist is required order PATHC / Pathology Consultation.

Shipping Instructions

Attach the green pathology address label and the pink Immunostain Technical Only label included in the kit to the outside of the transport container.

Specimen Required

Supplies: Immunostain Technical Only Envelope (T693)

Specimen Type: Tissue

Container/Tube: Immunostain Technical Only Envelope (T693)

Preferred: 2 unstained positively charged glass slide (25- x 75- x 1-mm) per test ordered; sections 4-microns thick.

Acceptable: Formalin-fixed, paraffin-embedded (FFPE) tissue block

Secondary ID


Useful For

Differentiating neurons (NF+) from glia (NF-)

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
IHTOI IHC Initial, Tech Only No No
IHTOA IHC Additional, Tech Only No No

Method Name


Reporting Name

NF (SMI31) IHC, Tech Only

Specimen Type


Specimen Stability Information

Specimen Type Temperature Time
TECHONLY Ambient (preferred)

Reject Due To








Wet/frozen tissue

Cytology smears

Nonformalin fixed tissue

Nonparaffin embedded tissue

Noncharged slides

ProbeOn slides

Clinical Information

Neurofilament antibody clone SMI 31 reacts with a phosphorylated epitope on neurofilament H and, to a lesser degree, neurofilament M. Both of these proteins contain multiple tandemly repeated serine phosphorylation sites. Clone SMI 31 reacts with thick and thin axons and specific dendrites such as basket cell dendrites. SMI 31 may also stain neuronal cell bodies in pathological conditions.


This test includes only technical performance of the stain (no pathologist interpretation is performed). Mayo Clinic cannot provide an interpretation of tech only stains outside the context of a pathology consultation. If an interpretation is needed, refer to test code PATHC / Pathology Consultation for a full diagnostic evaluation or second opinion of the case. All material associated with the case is required. Additional specific stains may be requested as part of the pathology consultation, and will be performed as necessary at the discretion of the Mayo pathologist.


The positive and negative controls are verified as showing appropriate immunoreactivity and documentation is retained at Mayo Clinic Rochester. If a control tissue is not included on the slide, a scanned image of the relevant quality control tissue is available upon request. Contact 855-516-8404.


Interpretation of this test should be performed in the context of the patient's clinical history and other diagnostic tests by a qualified pathologist.

Clinical Reference

1. Rudrabhatla P, Jaffe H, Pant HC: Direct evidence of phosphorylated neuronal intermediate filament proteins in neurofibrillary tangles (NFTs): phosphoproteomics of Alzheimer's NFTs. FASEB J 2011;25(11):3896-3905

2. Raina AK, Takeda A, Nunomura A, et al: Genetic evidence for oxidative stress in Alzheimer's disease. NeuroReport 1999;10:1355-1357

3. Yang CC, Alvarez RB, Engel WK, et al: Nitric oxide-induced oxidative stress in autosomal recessive and dominant inclusion-body myopathies. Brain 1998;121:1089-1097

4. Giasson BI, Mushynski WE: Aberrant stress-induced phosphorylation of perikaryal neurofilaments. J Biol Chem 1996;271(48):30404-30409

Day(s) and Time(s) Performed

Monday through Friday

Analytic Time

1 day

Performing Laboratory

Mayo Medical Laboratories in Rochester

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

88342-TC, primary

88341-TC, if additional IHC

LOINC Code Information

Test ID Test Order Name Order LOINC Value
NFSMI NF (SMI31) IHC, Tech Only In Process


Result ID Test Result Name Result LOINC Value
71358 NF (SMI31) IHC, Tech Only In Process


If not ordering electronically, complete, print, and send an Immunohistochemical (IHC)/In Situ Hybridization (ISH) Stains Request Form (T763) (