The reference range and within-person variability of thyroid stimulating hormone during the first and second trimesters of pregnancy

Haddow, J E; Knight, G J; Ge, Pengfei; McClain,; Pulkkinen, AJ

doi:10.1258/0969141042467340

Cited by 130 publications

(90 citation statements)

References 18 publications

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“…It is generally agreed that TSH levels are lower in early pregnancy (6), and it appears that lower values are also more desirable for the pregnancy outcome (16,20), but there is no generally accepted decision value for screening. Again, it should be method specific and population specific, and the cut-off values previously reported for hypothyroidism range from 5.2 to 2.0 mIU/l (2,8,13,14,17,(26)(27)(28)(29). Based on our previous experience (unpublished) that a value of 2.5 mIU/l brings too many false positives that are subsequently excluded from intervention when a combination of clinical history, (repeat) laboratory findings and ultrasonography is used, we selected 3.5 mIU/l as the screening cut-off value for TSH.…”

Section: Consensus Guideline Risk Factormentioning

confidence: 99%

Universal screening detects two-times more thyroid disorders in early pregnancy than targeted high-risk case finding

Horáček¹,

Špitálníková²,

Dlabalova

et al. 2010

European Journal of Endocrinology

101

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Objective: Screening of thyroid disorders in pregnancy has been controversial. Recent recommendations favour targeted high-risk case finding, though this approach may miss a significant number of those affected. We aimed to assess the prevalence of accepted high-risk criteria in women with autoimmune thyroiditis and/or hypothyroidism detected from universal screening in an iodinesufficient population. Design: In 400 non-selected women in the 9-11th gestational week, thyroid-related tests were performed, and those with abnormalities were offered consultation. Methods: TSH was determined by IRMA, and the upper cut-off value for screening was set at 3.5 mIU/l. For free thyroxine (FT 4 ) and thyroperoxidase antibodies (TPO-Ab), RIAs were used, with cut-offs of !10 pmol/l and O50 IU/ml respectively. Endocrinological consultation included Doppler ultrasonography and was aimed to confirm autoimmune thyroiditis and/or hypothyroidism. The prevalence of consensus high-risk criteria was assessed. Results: Among the 400 women, 65 (16.3%) had R1 abnormality: higher TSH was found in 10.3%, lower FT 4 in 2% and positive TPO-Ab in 8.3%. Fifty-one women were examined and followed up. Levo-T 4 treatment was initiated in 49 women for autoimmune thyroiditis (in 42), hypothyroidism (in 34) or both (in 27). Only 22 (45%) of 49 treated women fulfilled R1 high-risk criterion: most commonly family history (31%), history of miscarriage or preterm delivery (14%) and personal history (8%). Conclusions: Over half (55%) of pregnant women with abnormalities suggestive of autoimmune thyroiditis and/or hypothyroidism would be missed if only those with high-risk criteria were examined. A more extensive screening of thyroid autoimmunity and dysfunction seems warranted.

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Section: Consensus Guideline Risk Factormentioning

confidence: 99%

Universal screening detects two-times more thyroid disorders in early pregnancy than targeted high-risk case finding

Horáček¹,

Špitálníková²,

Dlabalova

et al. 2010

European Journal of Endocrinology

101

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“…Why TSH does not increase in women with low FT 4 remains to be established (85,105), although it is known that in areas with low iodine intake, low FT 4 can be found in association with normal TSH (2) due to an increased T 3 :T 4 ratio (1). What happens in areas without a clear deficiency of iodine?…”

Section: European Journal Of Endocrinologymentioning

confidence: 99%

CONTROVERSIES IN ENDOCRINOLOGY: On the need for universal thyroid screening in pregnant women

Vila

Velasco

González

et al. 2014

European Journal of Endocrinology

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There is a well-known controversy among scientific societies regarding the recommendation to screen for thyroid dysfunction (TD) during pregnancy. Although several studies have shown an association between maternal subclinical hypothyroidism and/or hypothyroxinemia with obstetric problems and/or neurocognitive impairment in the offspring, there is only limited evidence on the possible positive effects of thyroxine (T 4 ) treatment in such cases. Despite the scarcity of this evidence, there is a widespread agreement among clinicians on the need for treatment of clinical hypothyroidism during pregnancy and the risks that could arise due to therapeutic abstention. As maternal TD is a quite prevalent condition, easily diagnosed and for which an effective and safe treatment is available, some scientific societies have proposed to assess thyroid function during the first trimester of pregnancy and ideally before week 10 of gestational age. Given the physiologic changes of thyroid function during pregnancy, hormone assessment should be performed using trimester-specific reference values ideally based on locally generated data as geographic variations have been detected. Screening of TD should be based on an initial determination of TSH performed early during the first trimester and only if abnormal should it be followed by either a free or total T 4 measurement. Furthermore, adequate iodine supplementation during pregnancy is critical and if feasible it should be initiated before the woman attempts to conceive.

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“…Some researchers have established trimester-specific reference intervals for a local population ( The reference range for TSH is lower throughout pregnancy; both the lower normal limit and the upper normal limit of serum TSH are decreased by about 0.1-0.2 mIU/l and 1 mIU/l respectively, compared with the customary TSH reference interval of 0.4-4 mIU/l of non pregnant women. Serum TSH and its reference range rise gradually in the second and third trimesters, except for the study of Marwaha et al [84], but it is noteworthy that the TSH reference interval remains lower than in non pregnant women [80,81,85].…”

Section: Diagnosismentioning

confidence: 90%

11 Hypothyroidism in Pregnancy

Lazarus¹,

Pīrāgs²,

Butz³

2009

The Thyroid and Reproduction

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The reference range and within-person variability of thyroid stimulating hormone during the first and second trimesters of pregnancy

Abstract: Proper interpretation of TSH measurements during pregnancy requires that laboratories establish and monitor appropriate reference ranges. TSH levels show high within-person consistency between trimesters.

Cited by 130 publications

References 18 publications

Universal screening detects two-times more thyroid disorders in early pregnancy than targeted high-risk case finding

Universal screening detects two-times more thyroid disorders in early pregnancy than targeted high-risk case finding

CONTROVERSIES IN ENDOCRINOLOGY: On the need for universal thyroid screening in pregnant women

11 Hypothyroidism in Pregnancy

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