Browsing Tag

Immunology & Allergy

Immunochemistry, Test Utilization

Test Utilization: Cardiolipin Antibody Testing

Listed below are the Cardiolipin Antibody tests available in the Spectrum Health Regional Laboratory (SHRL) catalog. Please review the tests and the recommended test utilities.

Cardiolipin IgA testing should not be ordered unless the patient is negative for IgM and IgG. It should be restricted to very specific clinical scenarios for the evaluation of patients with suspected APS (Antiphospholipid Antibody Syndrome). Cardiolipin IgA requests will be reviewed for presence or absence of IgM/IgG testing.

Questions may be directed to Dr. David Alter by using the contact us link above.

Immunochemistry, Test Utilization

Utility of specific IgE (sIgE) testing to foods and food allergen components

The diagnostic evaluation of allergic disease occurs in the context of a patient’s complete clinical presentation. Important factors include, age, clinical signs and symptoms, relevant allergen exposures, and the performance characteristics (sensitivity, specificity, and predictive values) of the allergy tests themselves. Allergy tests yield information about sensitization to allergens, which is not always equivalent to allergic hypersensitivity (i.e., sensitivity); thus, interpretation in the context of clinical history is essential for accurate diagnosis. Continue Reading

Immunochemistry

New Allergens Now Available: Tree Nut Components, Nut Panel & Seafood Panel

The following tests are now available:

Tree Nut Component Allergens

In addition to allergen components for egg, milk, and peanut, the test menu at Spectrum Health Regional Laboratory has expanded to offer component testing for tree nuts.  Component testing measures sIgE antibodies to individual proteins unlike whole allergen testing which measures the presence of specific immunoglobulin E (sIgE) antibodies to a combination of allergenic and non-allergenic proteins.  This next generation testing identifies the source of sensitization and helps the clinician assess the risk of systemic reaction. Continue Reading

Immunochemistry

Rheumatoid Factor, Quantitative [Update]

As of June 21, 2016 the SHRL Immunochemistry department changed methods for Rheumatoid Factor, Quantitative (Test #8522, Epic #LAB206). In terms of interpretations, both methods compared well; however, the actual numerical results between methods are not interchangeable and a reference range change was required. The new ranges are listed below:

Interpretative ranges:
Negative :  <3.5 IU/ml
Equivocal:  3.5-5.0 IU/ml
Positive:   >5.0  IU/ml

This is only in effect at the Spectrum Health Regional Laboratory; Spectrum Health Gerber Laboratory is still performing using the immunoturbidimetric assay.

Chemistry, Referral/Sendouts, Test Utilization

Appropriate Thyroglobulin Tumor Marker and Anti-Thyroperoxidase Ordering Practices

Thyroid Peroxidase Antibody (anti-TPO), Blood Level (Test #8524 )
This is the recommended test for the evaluation of Autoimmune Thyroiditis

Thyroglobulin, Tumor Marker, Serum (Test #3069)
It is only indicated for monitoring of thyroid cancer treatment.
This result is reported with an Anti-Tg result to assess for possible interference.
This test should NOT be ordered for associated anti-Tg result provided by reference laboratory.

Thyroglobulin Antibody (anti-Tg) Test
Historically ordered with anti-TPO for evaluation of possible autoimmune thyroiditis.
The literature shows that anti-TPO, alone, has better sensitivity and specificity with only 5% of cases of Autoimmune thyroiditis with anti-TPO negative, anti-Tg positive.
Since 2/2011, requests for anti-Tg have been cancelled per Laboratory Communication: Memo Thyroglobulin Antibody 2/2011

Spectrum Health Regional Laboratory Experience February 2015 – March 2016 (13 months):
357 patients with both Anti-TPO and Anti-Tg results.
*Anti-Tg results were due to concomitantly ordered Thyroglobulin TM requests.
250 patients had positive Anti-TPO and/or Anti-Tg level
193 patients had both positive Anti-TPO and Anti-Tg level
56 patients had positive Anti-TPO and negative Anti-Tg level
1 patient had a negative Anti-TPO and positive Anti-Tg levels

Based on these results, and what is reported in the literature, we are confident of our current practices and strongly request discontinuation of Thyroglobulin TM requests for the associated Anti-Tg result

Caturegli P, De Remigis A, Rose NR. Hashimoto thyroiditis: clinical and diagnostic criteria. Autoimmun Rev. 2014 Apr-May;13(4-5):391-7

Immunochemistry, Test Utilization

Helicobacter Antibody Testing

Effective March 1, 2016, Mayo Medical Laboratories will no longer perform any Helicobacter Antibody (IgG, IgM, or IgA) testing. The Mayo Clinic has determined that Helicobacter antibody testing has a poor predictive value, and also has poor clinical sensitivity and specificity. While a negative antibody result suggests the absence of prior Helicobacter exposure, a positive result is not predictive of active Helicobacter infection. Furthermore, since antibody levels may remain positive for years following resolution of infection serologic testing cannot be used to distinguish active from past infection or document eradication of Helicobacter infection following treatment. See the full text of a recent Mayo Medical Laboratories Communique article on Helicobacter testing methods for further information on the various available tests for Helicobacter infection.

Effective as of the above date, the Helicobacter pylori Antibody IgM and Helicobacter pylori Antibody IgA tests will no longer be available through the Spectrum Health Laboratory. The Helicobacter pylori Antibody IgG test (#8596), which is performed in house, will continue to be available until further notice, but may be subject to further review at a later time. Some third party payers are now considering Helicobacter antibody tests to be medically unnecessary and no longer reimbursing for them.

The Helicobacter pylori breath test (#3013, available from the Spectrum Health Laboratory) and the Helicobacter pylori Antigen, Stool test (#4307, available as a send out to Mayo Medical Laboratories) are now considered the primary recommended tests for the diagnostic evaluation of suspected Helicobacter infection. Refer to the linked Mayo diagnostic algorithm for further information on recommended approaches to Helicobacter pylori diagnostic testing.

Any questions concerning these changes in Helicobacter pylori testing may be directed to Dr. Richard Horvitz in the Pathology Department.