Sir,We read with great interest the systematic review on trimester-specific normative values for thyroid function tests in Indian pregnant women by Kannan et al.[1]We agree that there is a great need for trimester-specific reference ranges from different parts of India and note the lack of such data from the western part of India.[1]Hence, we have analyzed the available data from our previous study to derive reference ranges for thyroid function in first trimester.[2]The study screened 483 pregnant women in the first trimester. Exclusion criteria included thyroid stimulating hormone (TSH) receptor antibody positivity (n = 3), family history of thyroid disorder (n = 12), known thyroid disorders on treatment (n = 10), goiter (n = 78), anti-thyroperoxidase (TPO) positivity (n = 60), overt hypothyroidism defined as TSH >10 μIU/ml (n = 3), and overt hyperthyroidism defined as TSH <0.01 μIU/ml (n = 14). A total of 137 women had at least one of the above exclusion criteria and were excluded from the analysis. The remaining 346 women were included in the analysis. Data was analysed using SPSS version 21 (IBM, Armonk, NY). The reference ranges for thyroid function tests are summarized in Table 1. Assay details of thyroid function tests and thyroid antibodies have been described previously.
Table 1
Thyroid function tests in first trimester
Thyroid function tests in first trimesterThe lower and upper limit of normal for thyroid function tests in the first trimester are summarized by Kannan et al. and vary across studies.[1]The lower and upper limit of normal for TSH and FT4 in first trimester were 0.09–1.92 μIU/ml, 0.64–0.93 ng/dl and 1.82–6.65 μIU/ml, 1.32–2.0 ng/dl, respectively. Our study reports a relatively lower lower limit of normal for first trimester TSH. Otherwise our study results were comparable to other studies from India.The study was limited by lack of adequate data for establishing reference ranges for second and third trimester. Although pregnant women from Maharashtra are generally considered iodine sufficient, iodine status of the study population was not evaluated.[3]
Authors: Morven I F A Lean; Mike E J Lean; Chittaranjan S Yajnik; Dattatray S Bhat; Suyog M Joshi; Deepa A Raut; Himangi G Lubree; Emilie Combet Journal: Public Health Nutr Date: 2013-05-09 Impact factor: 4.022
Authors: Vimal Nambiar; Varsha S Jagtap; Vijaya Sarathi; Anurag R Lila; Sadishkumar Kamalanathan; Tushar R Bandgar; Padmavathy S Menon; Nalini S Shah Journal: J Thyroid Res Date: 2011-07-17