Trimester-specific reference interval for Thyroid Function Tests in pregnant Filipino women

Perpetua Patal; Jarna Hamin; Aileen Bautista; Cecilia Jimeno; Laura Acampado; May Hipolito; Irmina Gomez; Mark Antonio; Efren Domingo; Mary Anne Lim-abrahan

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Trimester-specific reference interval for Thyroid Function Tests in pregnant Filipino women

Author: Perpetua Patal ¹ ; Jarna Hamin ¹ ; Aileen Bautista ¹ ; Cecilia Jimeno ¹ ; Laura Acampado ¹ ; May Hipolito ² ; Irmina Gomez ² ; Mark Antonio ² ; Efren Domingo ² ; Mary Anne Lim-Abrahan ¹
Author Information

1. Section of Endocrinology, Diabetes and Metabolism, Philippine General Hospital
2. Department of Obstetrics and Gynecology, Philippine General Hospital
Publication Type:Journal Article
Keywords: Reference interval; Pregnant Filipino women
MeSH: Thyroid Function Tests
From: Journal of the ASEAN Federation of Endocrine Societies 2016;31(1):18-22
CountryPhilippines
Language:English
Abstract: Background:The interpretation of thyroid hormone function during pregnancy is difficult due to its physiologic changes. Differences in iodine status in previous studies led to different intervals; therefore the use of trimester-specific, method-specific and probably country-specific reference values is advocated.
Objective:To establish trimester-specific reference interval for thyroid function tests in pregnant Filipino women.
Methodology:Six hundred sixteen pregnant patients (5–40 weeks gestation) attending a tertiary center were recruited. Level of serum thyroid stimulating hormone (TSH) was measured using immunoradiometric assay while free thyroxine (FT4), free triiodothyronine (FT3) and thyroid peroxidase antibodies (TPOAb) were measured by radioimmunoassay method. Main outcome measures are trimester-specific reference interval based on 2.5th and 97.5th percentiles for TSH, FT4 and FT3 among TPOAb-negative pregnant patients.
Results:The reference intervals for each trimester were as follows: TSH (0.05-4.24, 0.13-3.95, and 0.20-3.00 uIU/mL); FT4 (9.80-21.88, 9.10-18.95 and 9.16-18.64 pmol/L) and FT3 (2.40-6.20, 2.77-5.00 and 2.09-3.70 pmol/L). FT4 and FT3 are strongly and negatively correlated with age of gestation (p=<0.01and <0.01 respectively). No correlation is found with TSH and age of gestation (p=0.52).
Conclusions:Trimester-specific intervals among pregnant Filipino women are different from their non-pregnant counterparts and laboratory cutoffs. Thus, these reference values should be used in the country.
Full text:262-Article Text-3637-1-10-201605301.pdf