Hypothyroidism in Pregnancy

Zantour, B.; Alaya, W.; Marmouch, H.; Chebbi, Wafa

doi:10.5772/54745

Cited by 9 publications

(9 citation statements)

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“…The resultant arterial stiffness is an early marker of incident cardiovascular disease as well as a pathological feature of preeclampsia [ 1 ]. Due to the transfer of iodine across the placenta to the growing foetus and the increased physiological renal filtration and loss of iodine in urine during pregnancy, pregnant women in populations with insufficient iodine intake are at increased risk of worsening iodine deficiency [ 9 , 10 ]. This is now thought to lead to subclinical or overt hypothyroidism, endothelial dysfunction, preeclampsia, and other adverse pregnancy outcomes, such as miscarriage, preterm delivery, and intrauterine growth restriction [ 11–13 ].…”

Section: Introductionmentioning

confidence: 99%

Mildly elevated thyroid-stimulating hormone is associated with endothelial dysfunction and severe preeclampsia among pregnant women with insufficient iodine intake in Eastern Cape province, South Africa

2021

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Background: Preeclampsia and hypothyroidism are associated with endothelial dysfunction. Iodine deficiency is a risk factor for subclinical hypothyroidism in pregnancy. However, there is a paucity of data on the relationship between iodine nutrition state in pregnancy, the degree of endothelial dysfunction, and the risk of preeclampsia. Methods: Ninety-five normotensive pregnant women, 50 women with preeclampsia with no severe features, and 50 women with severe preeclampsia were enrolled into the current study from the maternity units of Nelson Mandela Academic Hospital and Mthatha Regional Hospitals in Eastern Cape Province, South Africa. Urinary iodine concentration (UIC), serum markers of thyroid function, aortic augmentation index, and pulse wave velocity (PWV) were compared. Results: Median UIC was 167.5, 127.7, and 88.5 mg/L, respectively for normotensive pregnant women, those with preeclampsia and severe preeclampsia (p ¼ .150). Participants with severe preeclampsia had significantly higher median thyroid-stimulating hormone (TSH) and oxidized LDL than normotensive and preeclamptic women without severe features (respectively 3.0, 2.3, and 2.3 IU/L; 1.2, 1.0, and 1.0 IU/L, p < .05). The median Aortic augmentation index was 7.5, 19.0, and 21.0 (p < .001), and the pulse wave velocity 5.1, 5.7, and 6.3, respectively for normotensive, preeclampsia, and severe preeclampsia participants (both p < .001). In linear regressions, TSH, age, and hypertensive disease were independent predictors of elevated PWV. Conclusion:Upper normal-range TSH levels in women with severe preeclampsia were associated with markers of endothelial dysfunction. The low UIC and trend towards the elevation of thyroglobulin suggest that inadequate iodine intake may have increased TSH levels and indirectly caused endothelial dysfunction.

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Section: Introductionmentioning

confidence: 99%

Mildly elevated thyroid-stimulating hormone is associated with endothelial dysfunction and severe preeclampsia among pregnant women with insufficient iodine intake in Eastern Cape province, South Africa

2021

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“…In addition, there is extra iodine demand due to the physiological increase in maternal thyroid hormone output. This is as a result of the oestrogen mediated increase in thyroid-binding globulin that progressively decreases the free T4 in the serum, transfer of iodine to the foetus and increased renal iodine clearance [26]. Therefore, women with mild-to-moderate iodine deficiency may develop severe iodine deficiency in pregnancy with resultant subclinical hypothyroidism (SCH), overt hypothyroidism (OH) or isolated T4 deficiency with resultant maternal and offspring short term and long-term complications [25–27].…”

Section: Introductionmentioning

confidence: 99%

The prevalence of insufficient iodine intake in pregnancy in Africa: protocol for a systematic review and meta-analysis

2019

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Background Insufficient iodine intake in pregnancy is associated with many adverse pregnancy outcomes. About 90% of African countries are at risk of iodine deficiency due to poor soils and dietary goitrogens. Pregnancy predisposes to insufficient iodine nutrition secondary to increased physiological demand and increased renal loss. Iodine deficiency is re-emerging in countries thought to be replete with pregnant women being the most affected. This review seeks to identify the degree of iodine nutrition in pregnancy on the entire African continent before and after the implementation of national iodization programmes. Methods A systematic search of published literature will be conducted for observational studies that directly determined the prevalence of insufficient iodine intake among pregnant women in Africa. Electronic databases and grey literature will be searched for baseline data before the implementation of population-based iodine supplementation and for follow-up data up to December 2018. Screening of identified articles and data extraction will be conducted independently by two investigators. Risk of bias and methodological quality of the included studies will be assessed using a risk of bias tool. Appropriate meta-analytic techniques will be used to pool prevalence estimates from studies with similar features, overall and by major characteristics including the region of the study, time period (before and after implementation of iodization programmes), sample size and age. Heterogeneity of the estimates across studies will be quantified and publication bias investigated. This protocol is reported according to Preferred Reporting Items for Systematic reviews and Meta-Analysis protocols (PRISMA-P) 2015 guidelines. Discussion This review will help ascertain the impact of national iodization programmes on the iodine nutrition status in pregnancy in Africa and advise policy on the necessity for monitoring and mitigating iodine deficiency in pregnancy in Africa. This review is part of a thesis that will be submitted to the Faculty of Health Sciences, University of Cape Town, for the award of a PhD in Medicine whose protocol has been granted ethics approval (UCT HREC 135/2018). In addition, the results will be published in a peer-reviewed journal. Systematic review registration PROSPERO CRD42018099434 Electronic supplementary material The online version of this article (10.1186/s13643-019-1092-7) contains supplementary material, which is available to authorized users.

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“…During pregnancy, there is increased renal perfusion with increased iodine filtration and urinary iodine excretion in addition to increased transfer of iodine to the fetus 22. Hence women with inadequate iodine intake are at risk of developing iodine deficiency in pregnancy and possibly at increased risk of developing subclinical or overt hypothyroidism and pre-eclampsia 21–23…”

Section: Introductionmentioning

confidence: 99%

Insufficient iodine nutrition status and the risk of pre-eclampsia: a protocol for systematic review and meta-analysis

et al. 2019

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IntroductionPre-eclampsia is one of the leading causes of maternal and perinatal morbidity and mortality worldwide. Although subclinical hypothyroidism (SCH) in pregnancy is one of the established risk factors for pre-eclampsia, the link between iodine deficiency, the main cause of hypothyroidism and pre-eclampsia remains uncertain. About two billion people live in areas with iodine insufficiency. The increased renal blood flow during pregnancy leading to increased renal iodine clearance together with the increased placental transfer of iodine to the fetus leads to further iodine deficiency in pregnancy. Iodine is one of the most potent exogenous antioxidants whose deficiency is associated with oxidant imbalance and endothelial dysfunction, one of the mechanisms associated with increased risk of pre-eclampsia.Methods and analysisA systematic search of published literature will be conducted for case–control studies that directly determined the iodine nutrition status of women with pre-eclampsia and appropriate normotensive controls. A similar search will be conducted for cohort studies in which the incidence of pre-eclampsia among pregnant women with adequate and inadequate iodine nutrition status was reported. Databases including MEDLINE, EMBASE, Google Scholar, SCOPUS and Africa Wide Information will be searched up to 31 December 2018. Screening of identified articles and data extraction will be conducted independently by two investigators. Risk of bias of the included studies will be assessed using a Newcastle-Ottawa Scale. Appropriate meta-analytic techniques will be used to pool prevalence and incidence rates, odds and relative risk of pre-eclampsia from studies with similar features, overall and by geographical regions. Heterogeneity of the estimates across studies will be assessed and quantified and publication bias investigated. This protocol is reported according to Preferred Reporting Items for Systematic Reviews and Meta-Analysis protocols (PRISMA-P) 2015 guidelines.Ethics and disseminationSince the proposed study will use published data, there is no requirement for ethical approval. This review seeks to identify the risk of pre-eclampsia associated with insufficient iodine nutrition in pregnancy. This will help to ascertain whether insufficient iodine intake may be an independent risk factor for pre-eclampsia. This will advise policy makers on the possibility of maximising iodine nutrition in pregnancy and reproductive age as one of the remedies for prevention of pre-eclampsia among populations at risk of inadequate iodine intake. This review is part of the thesis that will be submitted for the award of a PhD in Medicine to the Faculty of Health Sciences of the University of Cape Town. In addition the results will be published in a peer-reviewed journal.PROSPERO registration numberCRD42018099427.

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Hypothyroidism in Pregnancy

Cited by 9 publications

References 93 publications

Mildly elevated thyroid-stimulating hormone is associated with endothelial dysfunction and severe preeclampsia among pregnant women with insufficient iodine intake in Eastern Cape province, South Africa

Mildly elevated thyroid-stimulating hormone is associated with endothelial dysfunction and severe preeclampsia among pregnant women with insufficient iodine intake in Eastern Cape province, South Africa

The prevalence of insufficient iodine intake in pregnancy in Africa: protocol for a systematic review and meta-analysis

Insufficient iodine nutrition status and the risk of pre-eclampsia: a protocol for systematic review and meta-analysis

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