Trimester specific reference ranges of serum TSH, FT3 and FT4 during last trimester of pregnancy
Background: Pregnancy is a stress for thyroid gland. After decades of research it is recommended that normal reference ranges of thyroid hormones test during different phases of pregnancy are necessary. The objective of this study was to establish serum TSH, FT3 and FT4 levels during last trimester of pregnancy. Methods: This was a cross-sectional analytical study. Simple convenient sampling technique was applied and sample size was calculated using classical sample size calculation formula of Cochran. Serum TSH, FT3 and FT4 were estimated by ELIZA method. Results: Maternal group showed serum TSH levels of 1.79±0.85 mIU/L. Maternal serum FT3 levels were 1.711±2.089 pmol/L. Mean serum FT4 of Maternal group were 1.31±1.07 ng/dL, (Range: 0.78–5.20 ng/dl). Conclusion: Our study population trimester specific ranges of TSH, FT4 and FT3 were lower than latest international levels according to Guidelines of American Thyroid Association of 2017. These values may be used to compare thyroid dysfunction in pregnancy.
Pak J Physiol 2021;17(1):
Forehan S. Thyroid disease in the perinatal period. Aust Fam Physician 2012;41(8):578–81.
McElduff A, Morris J. Thyroid function tests and thyroid autoantibodies in an unselected population of women undergoing first trimester screening for aneuploidy. Aust N Z J Obstet Gynaecol 2008;48(5):478–80.
Lee RH, Spencer CA, Mestman JH, Miller EA, Petrovic I, Braverman LE, et al. Free T4 immunoassays are flawed during pregnancy. Am J Obstet Gynecol 2009;200(3):260.e1–6.
Medici M, Korevaar TI, Visser WE, Visser TJ, Peeters RP. Thyroid function in pregnancy: what is normal? Clin Chem 2015;61(5):704–13.
Lazarus J, Brown RS, Daumerie C, Hubalewska-Dydejczyk A, Negro R, Vaidya B. 2014 European thyroid association guidelines for the management of subclinical hypothyroidism in pregnancy and in children. Eur Thyroid J 2014;3(2):76–94.
De Groot L, Abalovich M, Alexander EK, Amino N, Barbour L, Cobin RH, et al. Management of thyroid dysfunction during pregnancy and postpartum: Endocrine Society Clinical Practice guidelines. J Clin Endocrinal Metab 2012;97:2543–65.
Männistö T, Surcel HM, Ruokonen A, Vääräsmäki M, Pouta A, Bloigu A, et al. Early pregnancy reference intervals of thyroid hormone concentrations in a thyroid antibody-negative pregnant population. Thyroid 2011;21(3):291–8.
Lazarus JH, Bestwick JP, Channon S, Paradice R, Maina A, Rees R, et al. Antenatal thyroid screening and childhood cognitive function. N Engl J Med 2012;366(6):493–501.
Stagnaro-Green A, Abalovich M, Alexander E, Azizi F, Mestman J, Negro R, et al. Guidelines of American Thyroid Association for diagnosis and management of thyroid disease during pregnancy and postpartum. Thyroid 2011;21(10):1081–125.
Stagnaro-Green A, Optimal care of pregnant women with thyroid disease J Clin Endocrinol Metab 2012;97:2619–22.
Azizi F, Mehran L, Amouzegar A, Alamdari S, Subetki I, Saadat N, et al. Prevalent Practices of thyroid disease during Pregnancy among Endocrinologist, Internists and General Practitioners. Int J Endocrinol Metab 2016:14:e29601.
Van Deventer HE, Mendu DR, Remaley AT, Soldin SJ, Inverse log linear relationship between TSH and FT4 measured by direct analog immune-assay and tandem mass spectrometry Clin Chem 2011;57:122–7.
Bocos-Terraz JP, Izquierdo-Alvarez S, Bencalero-Flores JL, Alvarez-Lauretha R, Anzar-Sauca A, Real Lopez E, et al, Thyroid hormones according to gestational age in pregnant Spanish women BMC Res Notes 2009;2:237.
Li C, Shan Z, Mao I, Wang W, Xie X, Zhou W, et al. Assessment of thyroid function during first trimester pregnancy: what is rational upper limit of serum TSH during first trimester in Chinese pregnant women J Clin Endocrinol Metab 2014;90:73–9.
Becker DV, Braverman LE, Delange F, Dunn JT, Franklyn JA, Hollowell JG, et al. Iodine supplementation for pregnancy and lactation —United States and Canada: Recommendations of the American Thyroid Association. Thyroid 2006 Oct;16(10):949–51.
American Thyroid Association. Thyroid Disease and Pregnancy 2017. Accessed on Aug 15, 2019. Available from: https://www.thyroid.org/thyroid-disease-pregnancy .
Calina D, Docea AO, Golokhvast KS, Sifakis S, Tsatsakis A, Makriiannakis A. Management of endocrinopathies in pregnancy: A review of current evidence. Int J Enviorn Public Health 2019;16;781.
Elhaj ET, Adam I, Ahmad MA, Latif MF. Trimester specific thyroid hormones reference ranges in Sudanese women. BMC Physiology 2016;16:5.
Alexander EK, Pearce EN, Brent GA, Brown RS, Chen H, Dosiou C, et al. Guidelines of American Association for the diagnosis and management of thyroid disease during pregnancy and postpartum. Thyroid 2017;17:315–89.
Yang X, Meng Y, Zhang Y, Zhang C, Guo F, Yang S, et al. Thyroid reference ranges during pregnancy in a large Chinese population and comparison with current guidelines. Chin Med J (Engl) 2019;132:505–11.
Copyright (c) 2021 Pakistan Journal of Physiology
This work is licensed under a Creative Commons Attribution-NoDerivatives 4.0 International License.
Pakistan Journal of Physiology, Pak J Physiol, PJP is FREE for research and academic purposes. It can be downloaded and stored, printed, cited and quoted with full reference of, and acknowledgement to the PJP.