Thyroid Research and Practice

LETTER TO THE EDITOR
Year
: 2019  |  Volume : 16  |  Issue : 1  |  Page : 51-

Trimester-specific reference ranges for thyroid function tests in South Indian women


Mahmood Dhahir Al-Mendalawi 
 Department of Paediatrics, Al-Kindy College of Medicine, University of Baghdad, Baghdad, Iraq

Correspondence Address:
Prof. Mahmood Dhahir Al-Mendalawi
Department of Paediatrics, Al-Kindy College of Medicine, University of Baghdad, P.O. Box 55302, Baghdad Post Office, Baghdad
Iraq




How to cite this article:
Al-Mendalawi MD. Trimester-specific reference ranges for thyroid function tests in South Indian women.Thyroid Res Pract 2019;16:51-51


How to cite this URL:
Al-Mendalawi MD. Trimester-specific reference ranges for thyroid function tests in South Indian women. Thyroid Res Pract [serial online] 2019 [cited 2019 Jun 26 ];16:51-51
Available from: http://www.thetrp.net/text.asp?2019/16/1/51/255304


Full Text



Sir,

It is worthy to comment on the interesting study by Rani et al. on the trimester-specific reference ranges for thyroid function tests (TFTs) in Indian women published in the September–December 2018 issue of Thyroid Research and Practice.[1] The authors found that the reference ranges for the first, second, and third trimesters were 0.08–2.24, 0.42–2.84, and 0.40–3.14 μIU/ml for thyroid-stimulating hormone, 0.68–1.44, 0.59–1.21, and 0.53–1.15 ng/dl for free thyroxine 4 (FT4), and 2.08–3.48, 1.81–3.81, and 1.86–3.38 pg/ml for FT3.[1] I presume that such results need to be cautiously taken. The authors mentioned three limitations that might cast some suspicions on the study results. These include the following: The sample size was small; the iodine status was not evaluated in the study population; and the intervals for total T3 and total T4 were not established.[1] I presume that the following methodological limitation might be additionally contributory. It is obvious that inter-individual differences in TFTs could partially be explained by ethnicity. Truly, ethnic differences in serum thyroid profile have been reported necessitating the need to employ ethnicity-specific reference to diagnose thyroid disease during pregnancy in multiethnic populations.[2],[3] To my knowledge, the population in India is polygenetic and it is an astonishing amalgamation of different ethnicities and cultures. The authors did not mention the exact ethnic backgrounds of the studied population. Despite the aforementioned limitations, the reported trimester-specific reference ranges for TFTs[1] could help in better evaluating the thyroid status during pregnancy in the clinical practice and researches.

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Conflicts of interest

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References

1Rani KS, Tirupati S, Sarathi V, Kumar KD. Trimester-specific reference ranges for thyroid function tests in South Indian women. Thyroid Res Pract 2018;15:117-21.
2Dhatt GS, Jayasundaram R, Wareth LA, Nagelkerke N, Jayasundaram K, Darwish EA, et al. Thyrotrophin and free thyroxine trimester-specific reference intervals in a mixed ethnic pregnant population in the United Arab Emirates. Clin Chim Acta 2006;370:147-51.
3Korevaar TI, Medici M, de Rijke YB, Visser W, de Muinck Keizer-Schrama SM, Jaddoe VW, et al. Ethnic differences in maternal thyroid parameters during pregnancy: The generation R study. J Clin Endocrinol Metab 2013;98:3678-86.