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Test Code Sm Smith (Sm) Antibodies, IgG, Serum

Important Note

  • This is the Smith Antibody Test
  • If physician order is written as Capital S, little m, CAN order Smith Antibody
  • If unable to determine how the order is written, MUST contact physician to verify if test is for Smith or Smooth Muscle Antibody

Reporting Name

Sm Ab, IgG, S

Useful For

Evaluating patients with clinical features suggestive of antinuclear antibody associated connective tissue disease and the confirmation of a diagnosis of systemic lupus erythematosus.

 

Testing for Smith antibodies is not useful in patients without demonstrable antinuclear antibodies.

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

Serum


Specimen Required


Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 0.5 mL

Collection Instructions: Centrifuge and aliquot serum into a plastic vial.


Specimen Minimum Volume

0.35 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 21 days
  Frozen  21 days

Reference Values

<1.0 U (negative)

≥1.0 U (positive)

Reference values apply to all ages.

Day(s) Performed

Monday through Saturday

Test Classification

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information

86235

LOINC Code Information

Test ID Test Order Name Order LOINC Value
SM Sm Ab, IgG, S 18323-6

 

Result ID Test Result Name Result LOINC Value
SM Sm Ab, IgG, S 18323-6

Interpretation

A positive anti-Smith antibody result in the appropriate clinical context is consistent with a diagnosis of systemic lupus erythematosus.

Clinical Reference

1. Tan EM, Kunkel HG. Characteristics of a soluble nuclear antigen precipitating with sera of patients with systemic lupus erythematosus. J Immunol. 1966;96(3):464-471

2. Zieve GW, Khusial PR. The anti-Sm immune response in autoimmunity and cell biology. Autoimmun Rev. 2003;2(5):235-240

3. Billings PB, Hoch SO. Characterization of U small nuclear RNA-associated proteins. J Biol Chem. 1984;259(20):12850-12856

4. Battle DJ, Kasim M, Yong J, et al. The SMN complex: an assembly machine for RNPs. Cold Spring Harb Symp Quant Biol. 2006;71:313-320

5. Aringer M, Costenbader K, Daikh D, et al. 2019 European League Against Rheumatism/American College of Rheumatology Classification Criteria for Systemic Lupus Erythematosus. Arthritis Rheumatol. 2019;71(9):1400-1412

6. van Beers JJBC, Schreurs MWJ. Anti-Sm antibodies in the classification criteria of systemic lupus erythematosus. J Transl Autoimmun. 2022;5:100155

7. Migliorini P, Baldini C, Rocchi V, Bombardieri S. Anti-Sm and anti-RNP antibodies. Autoimmunity. 2005;38(1):47-54

8. Kwon OC, Park MC. Risk of systemic lupus erythematosus flares according to autoantibody positivity at the time of diagnosis. Sci Rep. 2023;13(1):3068

9. Llorente MJ, Jimenez J, Gonzalez C, et al. Effectiveness of different methods for anti-Sm antibody identification. A multicentre study. Clin Chem Lab Med. 2005;43(7):748-752

Report Available

1 to 3 days

Method Name

Multiplex Flow Immunoassay