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| COMMENTARY |
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| Year : 2016 | Volume
: 9
| Issue : 4 | Page : 436-437 |
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Thyroid function tests: Possible forgotten error in testing
Viroj Wiwanitkit
Tropical Medicine, Hainan Medical University, Haikou, China; Faculty of Medicine, University of Nis, Nis, Serbia; Joseph Ayo Babalola University, Nigeria; Dr. D. Y. Patil Medical University, Pune, Maharashtra, India
| Date of Web Publication | 12-Jul-2016 |
Correspondence Address:
Viroj Wiwanitkit
Wiwanitkit House, Bangkhae, Bangkok - 10160, Thailand
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/0975-2870.186059
How to cite this article:
Wiwanitkit V. Thyroid function tests: Possible forgotten error in testing. Med J DY Patil Univ 2016;9:436-7 |
Thyroid function test is one of most commonly used investigation in clinical endocrinology. There are many patients with thyroid disorders that require thyroid function tests. As noted, there are many dilemmas and pitfalls regarding thyroid function tests.[1] The general practitioner has to be well aware of these pitfalls. Based on the concept of laboratory medicine, there are many concerns regarding the quality of any laboratory testing. For thyroid function tests also, the same holds good. Theoretically, the quality of the testing has to start from preanalytical step to postanalytical step.
Focusing on preanalytical step, the important considerations are on the rational use of the test. For thyroid function test, the problem of request without indication is not uncommon. According to the recent report by Werhun and Hamilton, “overused and under-evidenced” is common in primary care.[2] For the next step, preanalytical, the problem on appropriate patients' preparation, correct patient identification and requesting, blood specimen collection, and transportation should be discussed. According to the report by Wiwanitkit, from an ISO certified laboratory, preanalytical error is very common, and it is usually due to human error.[3] For example, Zemlin et al. audited laboratory request forms requesting thyroid function tests and found that “medication/s used by the patient and doctor's contact number were the most commonly incomplete parameters.”[4] Müller et al. studied the blood collection technique on thyroid function test and found that “a standardized and minimum compression time when drawing blood samples is recommended in order to eliminate this potential source of diagnostic error.”[5] Focusing on analytical step, there are many concerns on laboratory techniques, methodology, and interference. Focusing on interference, there are many “potential confounding factors, including alterations in normal physiology (e.g., pregnancy), intercurrent (nonthyroidal) illness, and medication usage (e.g., thyroxine, amiodarone, heparin).”[6] As noted by Wenzel, “numerous drugs may cause changes in the serum concentrations of T4 and of T3. If such alterations are not recognized an incorrect diagnosis may result.”[7] The use of quality control, both internal and external types, is needed for the analytical step of thyroid function test.[8] Focusing on postanalytical step, the validation of any test result is the rule. The pitfall in result distribution and reporting can also be seen. Finally, in post analytical step, the interpretation of the test by a physician in charge can also be incorrectly done in some difficult case. For example, Beckett found that “abnormalities in thyroid function tests in euthyroid patients are most likely found in nonthyroidal illness and the elderly”[9] and this can be a big problem in the interpretation of thyroid function test in the elderly and hospitalized patient. To combat the problem, McConnell said that “routine use of computer-generated reminders is one solution to this problem that is, now widely suggested.”[10]
It can be seen that the laboratory medicine quality rule must be applied for thyroid function test. The error can be seen at any step, and the control of error is needed since it means the guarantee of patients' safety.
| References | |  |
| 1. | Garg MK, Mahalla N, Harikumar KVS. Laboratory evaluation of thyroid function: Dilemmas and pitfalls. Med J DY Patil Univ 2016;9:430-6.   |
| 2. | Werhun A, Hamilton W. Thyroid function testing in primary care: Overused and under-evidenced? A study examining which clinical features correspond to an abnormal thyroid function result. Fam Pract 2015;32:187-91. |
| 3. | Wiwanitkit V. Types and frequency of preanalytical mistakes in the first Thai ISO 9002:1994 certified clinical laboratory, a 6-month monitoring. BMC Clin Pathol 2001;1:5. |
| 4. | Zemlin AE, Nutt L, Burgess LJ, Eiman F, Erasmus RT. Potential for medical error: Incorrectly completed request forms for thyroid function tests limit pathologists' advice to clinicians. S Afr Med J 2009;99:668-71. |
| 5. | Müller J, Závada M, Safarcík K. Effects of venous compression for blood sampling on the results of in vitro tests of thyroid function (author's transl). Nuklearmedizin 1979;18:82-5. |
| 6. | 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. [ PUBMED] |
| 7. | Wenzel KW. Pharmacological interference with in vitro tests of thyroid function. Metabolism 1981;30:717-32. [ PUBMED] |
| 8. | Hu LT, Wang ZG. Internal quality control practice of thyroid disease related tests and imprecision analysis in China. Clin Lab 2014;60:301-8. [ PUBMED] |
| 9. | Beckett GJ. The investigation of thyroid function. J Int Fed Clin Chem 1995;6:186-90. |
| 10. | McConnell TH, Ashworth CT, Ashworth RD, Nielsen CR. Algorithm-derived, computer-generated interpretive comments in the reporting of laboratory tests. Am J Clin Pathol 1979;72:32-41. [ PUBMED] |
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