A Scoping Review of Hashimoto´s Thyroiditis in Pregnancy: Associated Risks, Treatment, and the Pathological Role of the Gut Flora
Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
BACKGROUND: In recent years autoimmune disorders have become a global burden and are regarded as the number three cause of morbidity in the industrialised world today. Scientific knowledge suggests that there exists, besides genetics and environmental factors, a pathological significant relationship to the digestive system in triggering autoimmunity. Relatively little attention was paid to its huge impact on the thyroid gland function.
OBJECTIVE: By mapping the current state of research, this scoping review aimed to shed light on the underestimated potential of treating thyroid autoimmunity in pregnancy from a clinical and public health perspective based on an ever-growing body of evidence. The main objective was to examine how the autoimmune disorder Hashimoto’s Thyroiditis (HT) interferes with the health of mother & child, during and after pregnancy.
METHODS: This review followed the PRISMA guidelines for identifying, screening, and assessing eligibility of relevant literature. Obtained data relied on extensive literature screenings of two databases to identify all relevant sources: MEDLINE/PubMed combined with Google Scholar. Quantitative studies addressing parameters that refer to the health status of mother & child living in high-income countries were included. Studies involving participants without markers of HT and case-studies of all kinds were excluded. For data analysis the primary outcomes – associated risks and treatment effects of HT, and other determinants of health influencing HT – were of interest.
RESULTS: Seven observational and three experimental studies were considered in the data collection. Most interestingly, public health aspects were rarely considered in included studies and none of them explicitly addressed other determinants, such as pathological, social, or environmental factors affecting HT in pregnancy. On the other hand, associated markers of HT determined by elevated thyroid antibody levels in 50% of the studies can potentially be common markers of a "leaky gut" (intestinal permeability). In all cases with higher prevalence of TPOAb, significant associations with adverse effects were determined compared to controls. These include postpartum depression (OR, 2.8 (1.7-4.5); p < 0.05), adverse pregnancy outcomes (p = 0.02), and higher prevalence in newborns to develop HT (OR, 4.12; p = 0.001) or to be born with congenital malformations (p < 0.01). Moreover, therapy of TPOAb positive pregnant women with Levothyroxine (LT4) showed no effect on preventing progression to postpartum thyroiditis. Based on these outcomes, thyroid stimulating hormone (TSH) and thyroxine (FT4) appear as unreliable indicators for detecting HT. By contrast, TPOAb were raised despite taking medications. Nonetheless, treatment with LT4 is more effective in preventing miscarriages than other therapy options (81.2% vs. 54.5%; p < 0.05) or no treatment (3.5% vs. 13.8%; p < 0.05).
CONCLUSIONS: On the basis of the findings, this review is the first of its kind suggesting a pathological relationship between the gut flora and HT in pregnancy. Since study outcomes also revealed that children that were already exposed to TPOAb in the utero, report a higher prevalence of HT in the general population, prevention in pregnancy is of paramount epidemiological importance. Taking into account both the pathological relation between mother & child and that pregnant women with a personal or family history of autoimmunity are more prone to HT, this review recommends prenatal routine-screening for TPOAb in high-risk groups. This would improve current diagnostic practices and reduce associated health risks for mother & child.
Place, publisher, year, edition, pages
2016. , 58 p.
Centre for Public Health Report Series, ISSN 1651-341x ; 2016:11
Hashimoto´s Thyroiditis (HT), Pregnancy, Pathological, Gut Flora
Public Health, Global Health, Social Medicine and Epidemiology
IdentifiersURN: urn:nbn:se:umu:diva-131492OAI: oai:DiVA.org:umu-131492DiVA: diva2:1074514
Master's Programme in Public Health (one-year)
2016-05-23, Umeå Universitet, Umeå, 08:27 (English)
Schröders, Julia, PhD student
Coe, Anna-Britt, Associate Professor