GESTATION‑SPECIFIC REFERENCE INTERVALS FOR THE THYROID‑STIMULATING HORMONE (TSH) IN A SAMPLE OF PREGNANT WOMEN ATTENDING PRIMARY HEALTH CARE CENTERS IN BABYLON PROVINCE
Abstract
Considering to downward shift of the TSH reference range occurs during pregnancy, with a reduction in both the lower and the upper limit of maternal TSH relative to the typical nonpregnant TSH reference range and the changes in thyroid physiology associated with pregnancy and poor outcomes related to abnormal maternal thyroid function, international guidelines recommend using population-based trimester- specific reference intervals (RIs) for thyroid testing. The aimeof this study is establishing a suitable RI of thyroid-stimulating hormone (TSH) in pregnant Iraqi women in order to solve this problem.
Methods: A total of 40 women visiting primary health care centers in Babylon province aged 19 to 35 years (10 non pregnant women, 10 pregnant women in first trimesters: T1 (1-12 weeks), 10 pregnant women in second trimesters:T2 (13-25 weeks), and 10 pregnant women in third trimesters:T3(26-41 weeks) were used in the study. Women followed in primary health care centers in Babylon province were enrolled in the reference interval study after applying exclusion criteria related to medical and prenatal history.
Results: The upper limits for the TSH reference range in pregnant groups were all lower than that of upper reference limits of non pregnant group. Also the lowest value of the upper limit for TSH and T3 was detected in the second trimester, the lowest value of the lower limit for TSH and T3 was detected in the third trimester.
Conclusions: Establishing gestation- and laboratory-specific RIs, especially for TSH, is essential for diagnosing thyroid disorders in pregnancy. Maternal thyroid function, especially TSH and free T3, changed during the course of pregnancy.
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