Marwaha R K, Chopra S, Gopalakrishnan S, Sharma B, Kanwar R S, Sastry A, Singh S
Division of Endocrinology and Thyroid Research, Institute of Nuclear Medicine and Allied Sciences, Delhi, India.
BJOG. 2008 Apr;115(5):602-6. doi: 10.1111/j.1471-0528.2008.01673.x.
Interpretation of thyroid function tests during pregnancy needs trimester-related reference intervals from pregnant populations with minimal risk for thyroid dysfunction. While India has become iodine sufficient after two decades of salt iodisation, there is no normative data for thyroid function from healthy pregnant women of this country.
To determine trimester-specific reference ranges for free triiodothyronine (FT(3)), free thyroxine (FT(4)) and thyrotropin (TSH) from healthy pregnant Indian women.
Cross-sectional study in a reference population of pregnant women.
Primary care level obstetric department in India.
Women with uncomplicated pregnancy in any trimester.
Five hundred and forty-one apparently healthy pregnant women with uncomplicated single intrauterine gestations reporting to the Armed Forces Clinic in any trimester were consecutively recruited. Clinical examination, thyroid ultrasound for echogenicity and nodularity and estimation of FT(3), FT(4), TSH and antithyroid antibodies (antithyroperoxidase [anti-TPO] and antithyroglobulin [anti-Tg]) using electrochemiluminescence technique were carried out. From this entire sample, a disease- and risk-free reference population was obtained by excluding those with any known factor that could affect thyroid function or those who were being treated for thyroid dysfunction.
None.
Of the 541 consecutive pregnant women in different trimesters enrolled for the study, 210 women were excluded. The composition of reference population comprising 331 women was 107 in first trimester, 137 in second trimester and 87 in third trimester. The 5th and 95th percentiles values were used to determine the reference ranges for FT(3), FT(4) and TSH. The trimester-wise values in the first, second and third trimesters were: FT(3) (1.92-5.86, 3.2-5.73 and 3.3-5.18 pM/l), FT(4) (12-19.45, 9.48-19.58 and 11.32-17.7 pM/l) and TSH (0.6-5.0, 0.44-5.78 and 0.74-5.7 iu/ml), respectively. Analysis of mean, median values for FT(3), FT(4) and TSH between each trimester showed no significant difference in FT(3) and TSH values (95% CI). However, FT(4) showed significant variation between trimesters with values decreasing with advancing gestational age (P value: first versus second = 0.015, first versus third = 0.003 and second versus third = not significant). Women with antibody positivity and hypoechogenicity of thyroid gland had significantly higher TSH values when compared with women with antibody negativity and normoechogenicity.
Reference ranges of FT(3), FT(4) and TSH have been established for pregnant Indian women using 5th and 95th percentiles.
孕期甲状腺功能检查结果的解读需要依据甲状腺功能障碍风险最低的孕妇群体的孕期相关参考区间。尽管经过二十年的食盐碘化，印度已实现碘充足，但该国健康孕妇的甲状腺功能尚无规范数据。
确定印度健康孕妇孕期各阶段游离三碘甲状腺原氨酸（FT(3)）、游离甲状腺素（FT(4)）和促甲状腺激素（TSH）的参考范围。
对孕妇参考人群进行横断面研究。
印度基层医疗水平的产科部门。
孕期各阶段无并发症的孕妇。
连续招募了541名在孕期各阶段前往武装部队诊所就诊、单胎妊娠且无并发症的明显健康孕妇。进行了临床检查，并采用电化学发光技术对甲状腺进行超声检查以评估回声性和结节性，同时测定FT(3)、FT(4)、TSH及抗甲状腺抗体（抗甲状腺过氧化物酶[抗-TPO]和抗甲状腺球蛋白[抗-Tg]）。从整个样本中，通过排除任何已知可能影响甲状腺功能的因素或正在接受甲状腺功能障碍治疗的孕妇，获得了无疾病和风险的参考人群。
无。
在纳入研究的541名不同孕期的连续孕妇中，排除了210名。参考人群由331名女性组成，其中孕早期107名，孕中期137名，孕晚期87名。采用第5和第95百分位数来确定FT(3)、FT(4)和TSH的参考范围。孕早期、孕中期和孕晚期各阶段的值分别为：FT(3)（1.92 - 5.86、3.2 - 5.73和3.3 - 5.18 pM/l），FT(4)（第十二 - 19.45、9.48 - 19.58和11.32 - 17.7 pM/l），TSH（0.6 - 5.0、0.44 - 5.78和0.74 - 5.7 iu/ml）。各孕期之间FT(3)和TSH值的均值、中位数分析显示差异无统计学意义（95%可信区间）。然而，FT(4)在各孕期之间存在显著差异，其值随孕周增加而降低（P值：孕早期与孕中期 = 0.015，孕早期与孕晚期 = 0.003，孕中期与孕晚期 = 无统计学意义）。与抗体阴性且甲状腺回声正常的女性相比，抗体阳性且甲状腺回声减低的女性TSH值显著更高。
采用第5和第95百分位数为印度孕妇建立了FT(3)、FT(4)和TSH的参考范围。
