Region Specific Reference Intervals for TSH in the First Trimester of Pregnancy: A Three Year Retrospective Study BC01-BC03
Dr. Viswa Kalyan Kolli,
Associate Professor, Department of Biochemistry, GITAM Institute of Medical Sciences and Research, GITAM (Deemed to be University), Rushikonda, Visakhapatnam-530045, Andhra Pradesh, India.
Introduction: Alterations in thyroid hormones levels affect maternal health and fetal neurocognitive development. Variation in geophysical and socio-economic factors, and placental Human Chorionic gonadotropin (hCG) influence thyroid hormone secretion, and decreases Thyroid Stimulating Hormone (TSH) levels. Therefore, American Thyroid Association (ATA) recommends establishment of trimester and region-specific ranges for better detection and management of thyroid hormone dysfunction.
Aim: To determine the region-specific TSH values in the first trimester of pregnancy.
Materials and Methods: In the three-year retrospective study, serum TSH levels of 1221 healthy pregnant women attending the antenatal OPD at GITAM Institute of Medical Sciences and Research, Visakhapatnam, Andhra Pradesh, India, were measured by the Electrochemiluminescence Immunoassay â€śECLIAâ€ť. Reference interval of TSH was calculated using the Statistical Package for the Social Sciences (SPSS) software by applying the non-parametric statistical method. The central 95% intervals (normal range), the 90% confidence intervals and the confidence ratios were calculated.
Results: For TSH levels in the first trimester, the central 95% intervals were 0.43-4.5 mU/L, 90% confidence intervals were 0.27-0.45 (Upper Limit), 3.9-4.84 (Lower Limit) and the confidence ratio was 0.24. These values were found to be slightly higher than the ATA 2017 guidelines.
Conclusion: Our region-specific reference interval for TSH was found to be 0.43-4.5 mU/L. The established region-specific reference intervals will help assessment of TSH levels in the first trimester of pregnancy and thereby prevent misdiagnosis and inadequate treatment.