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Permanent Unavailability of Nichols Advantage Thyroglobulin Assay
Announcement from American Thyroid Association, 2006

Background

Patients with differentiated thyroid carcinoma, which includes papillary, follicular and Hürthle cell thyroid carcinomas, ordinarily have serial measurements of serum thyroglobulin levels that help identify those with persistent or recurrent tumor.

The precise level of thyroglobulin is important. In addition, it is critical to know whether the thyroglobulin levels are rising or falling.

Therefore. the American Thyroid Association’s Thyroid Cancer Guidelines (2006) state that serum thyroglobulin levels should be measured by an immunometric assay, ideally in the same laboratory and using the same assay during followup in patients who have undergone total or near-total thyroidectomy and thyroid remnant ablation.

The following message concerns important information about this assay.

ATA Message to Physicians, Summer 2006

The Laboratory Services Committee of the American Thyroid Association has alerted physicians that the Nichols Advantage Thyroglobulin Assay which has been used by many major laboratories across the country has become permanently unavailable.

For patients with differentiated thyroid cancer (papillary, follicular, Hurthle cell, and other variants), the accurate measurement of serum thyroglobulin serves as an essential tool to monitor their disease.

The absence of detectable thyroglobulin in a patient’s blood is a good sign that the disease is in remission, while an increase in thyroglobulin levels may indicate that the cancer is growing.

Since thyroglobulin assay methods are not interchangeable, the results from a new assay may not be directly comparable to the previous assay. A recent publication speaks to the magnitude of the potential differences in reported thyroglobulin level between assay methods (1).

Patients who are due to have their thyroglobulin level measured should ask their physicians if the thyroglobulin assay method has been changed.

Physicians should ask their clinical laboratory if a new thyroglobulin assay is being substituted, and, if so, how the results compare to those previously obtained.

(1) Spencer CA, Bergoglio LM, Kazarosyan M, Fatemi S, Lopresti JS 2005 Clinical Impact of Thyroglobulin (Tg) and Tg autoantibody Method Differences on the Management of patients with Differentiated Thyroid Carcinomas. J Clin Endocrinol Metab 90:5566-75

Note from ThyCa: Thyroid Cancer Survivors' Association: For information about Thyroglobulin testing, written by Carole A. Spencer, Ph.D., visit this page on the ThyCa web site: http://www.thyca.org/thyroglobulin.htm

Last updated:  May 02, 2008