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| LETTERS TO THE EDITOR |
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| Year : 2020 | Volume
: 24
| Issue : 2 | Page : 226-227 |
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Mildly elevated TSH, high free T3, and normal free T4: Antiidiotype antibody effect
Won Sriwijitalai1, Viroj Wiwanitkit2
1 RVT Medical Center, Bangkok, Thailand
2 Department of Community Medicine, Dr. DY Patil University, Pune, Maharashtra, India
| Date of Submission | 24-Dec-2019 |
| Date of Acceptance | 24-Dec-2019 |
| Date of Web Publication | 30-Apr-2020 |
Correspondence Address:
Won Sriwijitalai
RVT Medical Center, Bangkok
Thailand
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/ijem.IJEM_647_19
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 2021 Mar 7];24:226-7. Available from: https://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
Click here to view |
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 | |  |
| 1. | Hidaka Y. Standardization of thyroid function tests. Rinsho Byori 2016;64:960-4.  |
| 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. |
| 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. |
| 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. |
| 5. | Kricka L Human anti-animal antibody interferences in immunological assays. J Clin Chem 1999;45:942-56. |
[Table 1]
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