Pregnancy
Pregnant women who are positive for Hashimotos thyroiditis may have decreased thyroid function or the gland may fail entirely. If a woman is TPOAb-positive, clinicians can inform her of the risks for herself and her infant if the disease goes untreated. "Thyroid peroxidase antibodies (TPOAb) are detected in 10% of pregnant women", which presents risks to those pregnancies. Women who have low thyroid function that has not been stabilized are at greater risk of having an infant with: low birth weight, neonatal respiratory distress, hydrocephalus, hypospadias, miscarriage, and preterm delivery. The embryo transplantion rate and successful pregnancy outcomes are improved when Hashimotos is treated. Recommendations are to treat pregnant women only if they are TPOAb-positive throughout the entirety of their pregnancies and to screen all pregnant women for thyroid levels. Close cooperation between the endocrinologist and obstetrician benefits the woman and the infant. The Endocrine Society recommends screening in pregnant women who are considered high-risk for thyroid autoimmune disease.Thyroid peroxides antibodies testing is recommended for women who have ever been pregnant regardless of pregnancy outcome. "[P]revious pregnancy plays a major role in development of autoimmune overt hypothyroidism in premenopausal women, and the number of previous pregnancies should be taken into account when evaluating the risk of hypothyroidism in a young women [sic]. "Hormonal changes and trophoblast expression of key immunomodulatory molecules lead to immunosuppression and fetal tolerance. Main players in regulation of the immune response are Tregs. Both cell-mediated and humoral immune responses are attenuated, resulting in immune tolerance and suppression of autoimmunity.
Specific HLA alleles have a higher affinity to autoantigenic thyroidal peptides and can contribute to autoimmune thyroid disease development. Specifically, in Hashimotos disease, aberrant expression of HLA II on thyrocytes has been demonstrated. They can present thyroid autoantigens and initiate autoimmune thyroid disease. Susceptibility alleles are not consistent in Hashimotos disease. In Caucasians, various alleles are reported to be associated with the disease, including DR3, DR5 and DQ7. CTLA-4 genes
This gene is the second major immune-regulatory gene related to autoimmune thyroid disease. CTLA-4 gene polymorphisms may contribute to the reduced inhibition of T-cell proliferation and increase susceptibility to autoimmune response. CTLA-4 is a major thyroid autoantibody susceptibility gene. A linkage of the CTLA-4 region to the presence of thyroid autoantibodies was demonstrated by a whole-genome linkage analysis. CTLA-4 was confirmed as the main locus for thyroid autoantibodies. Protein tyrosine phosphatase nonreceptor-type 22 gene
PTPN22 is the most recently identified immune-regulatory gene associated with autoimmune thyroid disease. It is located on chromosome 1p13 and expressed in lymphocytes. It acts as a negative regulator of T-cell activation. Mutation in this gene is a risk factor for many autoimmune diseases. Weaker T-cell signaling may lead to impaired thymic deletion of autoreactive T cells, and increased PTPN22 function may result in inhibition of regulatory T cells, which protect against autoimmunity. Immune-related genes
IFN-γ promotes cell-mediated cytotoxicity against thyroid mutations causing increased production of IFN-γ were associated with the severity of hypothyroidism.