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LETTERS TO THE EDITOR
Year : 2020  |  Volume : 24  |  Issue : 2  |  Page : 226-227

Mildly elevated TSH, high free T3, and normal free T4: Antiidiotype antibody effect


1 RVT Medical Center, Bangkok, Thailand
2 Department of Community Medicine, Dr. DY Patil University, Pune, Maharashtra, India

Date of Submission24-Dec-2019
Date of Acceptance24-Dec-2019
Date of Web Publication30-Apr-2020

Correspondence Address:
Won Sriwijitalai
RVT Medical Center, Bangkok
Thailand
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijem.IJEM_647_19

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How to cite this article:
Sriwijitalai W, Wiwanitkit V. Mildly elevated TSH, high free T3, and normal free T4: Antiidiotype antibody effect. Indian J Endocr Metab 2020;24:226-7

How to cite this URL:
Sriwijitalai W, Wiwanitkit V. Mildly elevated TSH, high free T3, and normal free T4: Antiidiotype antibody effect. Indian J Endocr Metab [serial online] 2020 [cited 2020 Jun 2];24:226-7. Available from: http://www.ijem.in/text.asp?2020/24/2/226/283565



Sir,

Thyroid function test is a common endocrine laboratory investigation. The common profiles of thyroid function test include thyrotropin (TSH), total and free thyroxine (T4), and triiodothyronine (T3).[1] Similar to other clinical chemistry tests, the aberration of thyroid function due to interference is possible.[2],[3] The interference by antibody is possible but little mentioned in the literature. Here, the authors present a case with mildly elevated TSH, high free T3, and normal free T4. The case is a consulted case to the clinical laboratory by the physician in charge due to suspicious incorrect laboratory result. The result is a result of a female patient who is in euthyroid state. In this patient, the thyroid function test is mildly elevated TSH, high free T3, and normal free T4 (by analyzer 1, one-step chemiluminescent immunoassay based on a specific anti-T3 sheep monoclonal antibody) and the result for anti-thyroid peroxidase antibody and anti-thyroglobulin antibody is negative. The tests for TSH, free T3, and free T4 are repeated by a different analyzer with a different technique and the results are hereby presented in [Table 1] (analyzer 2, one-step chemiluminescent immunoassay based on anti-b TSH antibody and anti-a TSH acridinium labeled conjugate).
Table 1: The results of thyroid function test of the patient by different analyzers

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The interesting issue is on the unexplained elevation of free T3 by the analyzer 1. Indeed, this is due to the interference by antiidiotype antibodies in the first method used by the analyzer 1. This is a possible but little mentioned interference problem in thyroid function test. The practitioner should recognize the possibility of antibody interference when interpreting an aberrant thyroid function test result.[4],[5] In a recent report, the aberrant false thyroid function test result leads to a lot of missed diagnosed and unnecessary patient management.[3]

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

1.
Hidaka Y. Standardization of thyroid function tests. Rinsho Byori 2016;64:960-4.  Back to cited text no. 1
    
2.
Favresse J, Burlacu MC, Maiter D, Gruson D. Interferences with thyroid function immunoassays: Clinical implications and detection algorithm. Endocr Rev 2018;39:830-50.  Back to cited text no. 2
    
3.
Koulouri O, Moran C, Halsall D, Chatterjee K, Gurnell M. Pitfalls in the measurement and interpretation of thyroid function tests. Best Pract Res Clin Endocrinol Metab 2013;27:745-62.  Back to cited text no. 3
    
4.
Morgenthaler NG, Froehlich J, Rendl J, Willnich M, Alonso C, Bergmann A, et al. Technical evaluation of a new immunoradiometric and a new immunoluminometric assay for thyroglobulin. Clin Chem 2002;48:1077-83.  Back to cited text no. 4
    
5.
Kricka L Human anti-animal antibody interferences in immunological assays. J Clin Chem 1999;45:942-56.  Back to cited text no. 5
    



 
 
    Tables

  [Table 1]



 

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