Abdul Rehman Khokhar, Abdul Majeed Cheema.
Trimester specific reference ranges of serum tsh, ft3 and ft4 during last trimester of pregnancy.
Pak J Physiol Jan ;17(1):19-22.

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.

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