TEST CATALOG ORDERING & RESULTS SPECIMEN HANDLING CUSTOMER SERVICE EDUCATION & INSIGHTS
Test Catalog

Test ID: SSAB    
SS-A and SS-B Antibodies, IgG, Serum

Useful For Suggests clinical disorders or settings where the test may be helpful

Evaluating patients with signs and symptoms of a connective tissue disease in whom the test for antinuclear antibodies is positive, especially those with signs and symptoms consistent with Sjogren syndrome or lupus erythematosus

 

This test is not useful in patients without demonstrable antinuclear antibodies.

Testing Algorithm Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

See Connective Tissue Disease Cascade (CTDC) in Special Instructions.

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Sjogren syndrome (SS)A (Ro), SSB (La), ribonucleoprotein (RNP), and Smith (Sm) proteins are autoantigens commonly referred to as extractable nuclear antigens (ENA). Antibodies to ENA are common in patients with connective tissue diseases (systemic rheumatic diseases).

 

SSA or Ro is composed of protein antigens of 52 kD and 60 kD combined with cytoplasmic RNA species. SSA antibodies occur in patients with several different connective tissue diseases including Sjogren syndrome, an autoimmune disease that involves primarily the salivary and lachrymal glands (up to 90% of cases); systemic lupus erythematosus (SLE) (40%-60% of cases); and rheumatoid arthritis. SSA antibodies are associated with childhood SLE, neonatal SLE, and with congenital heart block in infants born to mothers with SLE.(1,2) SSA antibodies have also been reported to be associated with features of extraglandular inflammation in patients with SLE including vasculitis, purpura, cytopenias, and adenopathy.

 

SSB or La is composed of a 48-kD protein combined with RNA species. SSB antibodies are found primarily in patients with Sjogren syndrome or SLE, where they occur with frequencies of approximately 60% and 15%, respectively.(1,2) SSB antibodies occur only infrequently in the absence of SSA antibodies.

 

See Connective Tissue Disease Cascade (CTDC) in Special Instructions.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

SS-A/Ro ANTIBODIES, IgG

<1.0 U (negative)

> or =1.0 U (positive)

Reference values apply to all ages.

 

SS-B/La ANTIBODIES, IgG

<1.0 U (negative)

> or =1.0 (positive) 

Reference values apply to all ages.

Interpretation Provides information to assist in interpretation of the test results

A positive result for SSA (Ro) or SSB (La) antibodies is consistent with connective tissue disease, including Sjogren syndrome, lupus erythematosus (LE), or rheumatoid arthritis.

 

A positive result for SSA antibodies in a woman with LE prior to delivery indicates an increased risk of congenital heart block in the neonate.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

No significant cautionary statements

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Homburger H, Larsen S: Detection of specific antibodies. In: Rich R, Fleisher T, Schwartz B, et al, eds. Clinical Immunology: Principles and Practice. Mosby-Year Book; 1996:2096-2109

2. Kotzin B, West S: Systemic lupus erythematosus. In: Rich R, Fleisher T, Shearer E, et al, eds. Clinical Immunology Principles and Practice. 2nd ed. Mosby-Year Book; 2001:60.1-60.24

3. Rifai N, Horvath AR, Wittwer CT, eds: Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 6th ed. Elsevier; 2018

Special Instructions Library of PDFs including pertinent information and forms related to the test