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CC BY-NC-ND 4.0 · J Lab Physicians 2022; 14(02): 183-189
DOI: 10.1055/s-0041-1736520
Original Article

First-Trimester Reference Intervals for Thyroid Function Testing among Women Screened at a Tertiary Care Hospital in India

Rachita Nanda 
1   Department of Biochemistry, All India Institute of Medical Sciences, Raipur, Chhattisgarh, India
,
Prasanta Kumar Nayak
2   Department of Obstetrics and Gynecology, All India Institute of Medical Sciences, Raipur, Chhattisgarh, India
,
Suprava Patel
1   Department of Biochemistry, All India Institute of Medical Sciences, Raipur, Chhattisgarh, India
,
Eli Mohapatra
1   Department of Biochemistry, All India Institute of Medical Sciences, Raipur, Chhattisgarh, India
,
Sarita Agrawal
2   Department of Obstetrics and Gynecology, All India Institute of Medical Sciences, Raipur, Chhattisgarh, India
› Author Affiliations
Funding Statement The authors would like to thank Chhattisgarh Council of Science and Technology for sanctioning grants vide council letter no. 172/CCOST/218.
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Abstract

Objectives Due to differences in the method of assay and population-specific factors, each laboratory needs to establish its own gestation-specific reference intervals (GRIs) for thyroid hormones.

Materials and Methods Three-hundred forty-one women with less than 14 weeks gestation were screened at a tertiary care hospital in Chhattisgarh, India. Serum levels of thyroid-stimulating hormone (TSH), free thyroxine (fT4), and thyroid peroxidase antibody (anti-TPO) were measured using an ADVIA Centaur XP immunoassay.

GRIs (2.5th and 97.5th percentiles) were determined for TSH and fT4. TSH and fT4 concentrations were converted to multiples of the median (MoM) values. Effect of maternal age, gestational age, and maternal weight was analyzed.

Statistical Analysis Quantitative variables were expressed as means and standard deviations (SD), and qualitative variables were expressed as frequencies and percentages. Normality of the data was checked using the Kolmogorov–Smirnov test. Values that were normally distributed were expressed only as means and SD. Those that were not normally distributed were expressed as medians and interquartile range. For all statistical analysis, p < 0.05 was considered as statistically significant.

Results First-trimester GRI was 0.245 to 4.971 mIU/L for TSH, 10.2 to 18.9 pmol/L for fT4, and 27.0 to 56.89 kIU/L for anti-TPO. There was no significant difference in the mean serum TSH (p = 0.920), fT4 (p  = 0.714), or anti-TPO (p = 0.754) values among women in 4 to 7th week and 7 to 14th week of gestation. The 1st and 99th centile MoMs were 0.03 and 4.09 for TSH and 0.66 and 1.39 for fT4. There was a significant positive correlation between the maternal weight and TSH MoM values (p = 0.027, r = 0.120).

Conclusion These laboratory- and first-trimester-specific GRI for TSH and fT4 shall help in proper diagnosis and treatment of subclinical thyroid dysfunctions. TSH and fT4 MoM values can be used to indicate high or low values in a quantitative manner independent of the reference ranges and may be used by other laboratories.

Keywords

thyroid-stimulating hormone - thyroxine - reference range - pregnancy - multiple of median

Authors' Disclosure Statement

No competing financial or personal interest.


Authorship Participation

R.N. was involved in concept and design of work, sample analysis, and wrote first draft of the manuscript. P.K.N. was involved in design of work, acquisition, and analysis of data. S.P. was involved in interpretation of data and drafting of manuscript. E.M. was involved in sample analysis and revising the work critically, and S.A. was involved in acquisition and interpretation of data and revising the work critically. All authors have reviewed and approved of the manuscript prior to submission.


This manuscript has been submitted solely to this journal and is not published in press or submitted elsewhere.


Ethical Approval

Approval taken from Institute Ethics Committee, AIIMS Raipur AIIMSRPR/IEC/2016/019.


Supplementary Material



Publication History

Article published online:
10 November 2021

© 2021. The Indian Association of Laboratory Physicians. This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/)

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