Establishment of Trimester-Specific Reference Intervals of Serum TSH & fT4 in a Pregnant Indian Population at North Kolkata

Abstract

Reference intervals (RIs) of serum thyroid stimulating hormone (TSH) and free thyroxine (fT4) were determined in 402 healthy pregnant women by enzyme-linked immunosorbent assay (ELISA) technique after partitioning them into three trimesters. The reference population was chosen from a study population of 610 pregnant females by applying strict inclusion and exclusion criteria. The assays were done using proper quality control measures. RIs were calculated from the central 95 % of the distribution of TSH and fT4 values located between the lower reference limit of 2.5 percentile and upper reference limit of 97.5 percentile value 0.90 confidence intervals for the upper and lower reference limits were also determined. The reference intervals for TSH were 0.25-3.35 μIU/ml for the first trimester; 0.78-4.96 μIU/ml for the second trimester and 0.89-4.6 μIU/ml for the third trimester. Similarly, the reference intervals for fT4 for first, second and third trimesters were 0.64-2.0, 0.53-2.12 and 0.64-1.98 ng/dl respectively. The values thus obtained varied from those provided by the kit literature. In comparison to our derived reference intervals, the reference data from kit manufacturer under-diagnosed both subclinical hypo- and hyper-thyroidism within our pregnant reference population.

Trimester-specific reference interval for thyroid hormones during pregnancy at a Tertiary Care Hospital in Haryana, India

“…[101112141516171819202122232425] Soldin et al . [15] showed that FT4 decreased from the 1 st to 3 rd trimester ( P < 0.001), but there was no significant difference between the second to the third trimester.…”

“…In India, limited data's are available over trimester-specific thyroid hormones level during pregnancy and none from Haryana. [89101112] The aim of this study was to establish trimester-specific reference range for thyroid hormone during pregnancy in a tertiary care center in Haryana which is an iodine sufficient area of India.…”

Specific Reference Intervals of Serum Triiodothyronine, Thyroxine, and Thyroid-stimulating Hormone in Normal Pregnant Indian Women as per Trimester

“…Untreated and undetected gestational thyroid disorders are known to cause many complications like anemia, pregnancy-induced hypertension , hemorrhage, preterm delivery in mothers, and low birth weight, prematurity, congenital malformation, intrauterine fetal death, and lower intelligence quotient in children. 12 In recent years, various studies recommend the use of routine thyroid function tests for screening of thyroid disease during normal antenatal checkup. 13,14 Hence, selection and proper interpretation of gestational thyroid function parameters are important for the well-being of both the mother and the fetus.…”

Specific Reference Intervals of Serum Triiodothyronine, Thyroxine, and Thyroid-stimulating Hormone in Normal Pregnant Indian Women as per Trimester

“…Untreated and undetected gestational thyroid disorders are known to cause many complications like anemia, pregnancy-induced hypertension, hemorrhage, preterm delivery in mothers and low birth weight, prematurity, congenital malformation, intrauterine fetal death, and lower intelligence quotient in children. 12 In recent years, various studies recommend the use of routine thyroid function tests for screening of thyroid disease during normal antenatal checkup (ANC). 13,14 Hence, selection and proper interpretation of gestational thyroid function parameters are important for the wellbeing of both the mother and the fetus.…”