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

Abstract

ABSTRACT Aim Maternal thyroid hormone level during pregnancy is a vital parameter for the health of mother as well as developing child. Fetal growth is affected by maternal thyroid levels. Various physiological changes like alterations of thyroxine binding globulins (TBGs), beta-human chorionic gonadotropin (β-hCG) level, and change of iodide metabolism affect maternal thyroid hormone levels. Therefore, reference intervals (RI) for thyroid hormones in pregnant population require to be established separately from general population. Materials and methods The RIs of serum triiodothyronine (T3), thyroxine (T4), and thyroid-stimulating hormone (TSH) were determined in healthy pregnant women by enzyme-linked immunosorbent assay (ELISA) technique after segregating them into three trimesters. This study was conducted in a 492-bedded zonal level hospital. The reference population was chosen from a study population of pregnant women by strict inclusion and exclusion criteria. The assays were done by the most commonly used economical ELISA method using standard kits. Tests were done using accurate and precise methods with proper quality control measures. Results The RIs were calculated from the central 95% of distribution of total T3, total T4, and TSH values located between 2.5 and 97.5 percentile values. The 0.90 confidence intervals (CIs) for the upper and lower reference limits were calculated. The values thus obtained were different from those provided by manufacturer kit literature. Conclusion It is recommended to determine own laboratory-specific, method-specific, trimester-wise RI for maternal thyroid hormone status and use them for screening of pregnant mothers. How to cite this article Chakrabarty BK, Mitra B, Pal R, Hazra N. Specific Reference Intervals of Serum Triiodothyronine, Thyroxine, and Thyroid-stimulating Hormone in Normal Pregnant Indian Women as per Trimester. Indian J Med Biochem 2017;21(2):96-100.