Comparative frequency of four different types of pregnancy-associated thyrotoxicosis in a single thyroid centre

Advances in the differential diagnosis of transient hyperthyroidism in pregnancy and Graves' disease

BACKGROUND

The occurrence of thyrotoxicosis during pregnancy is mainly attributed to gestational transient thyrotoxicosis (GTT) and Graves' disease (GD). It is important to distinguish between GTT and Graves' disease because the two diseases are treated very differently. However, a gold standard for the differential diagnosis of the two diseases is currently lacking, and the most common method of differentiation is based on past medical history and clinical presentation combined with thyroid-related antibodies.

METHODS

A literature search of the electronic databases PubMed, Embase, Medline, Google Scholar, Cochrane Library, China Knowledge Infrastructure, Wanfang Database, Chinese Scientific Journals Full Text Database and China Biomedical CD-ROM was performed. The search period ranged from journal inception until 2022. We used the following search terms in "All fields": {["thyroid" (common field) OR "thyroid" (subject line)] OR "hyperthyroidism" (common field)} AND {["pregnancy" (title) OR "pregnancy" (title)] AND "one over" (common field)} OR {["pregnancy" (common field) OR "pregnancy" (common field) OR "pregnancy" (subject line)] AND "Graves'" (common field)}.

RESULTS

In recent years, some clinical studies at home and abroad have proposed other meaningful differential indicators, such as thyroid stimulating hormone, chorionic gonadotropin, thyroid hormone levels and thyroid ultrasound.

CONCLUSION

The differential diagnostic significance of each of these indicators is summarised here with the goal of providing a better reference for the differential diagnosis of hyperthyroidism during pregnancy in clinical practice.

Knowledge Gaps and Current Evidence Regarding Breastfeeding Issues in Mothers with Chronic Diseases

The prevalence of chronic maternal disease is rising in the last decades in the developed world. Recent evidence indicated that the incidence of chronic maternal disease ranges from 10 to 30% of pregnancies worldwide. Several epidemiological studies in mothers with chronic diseases have mainly focused on the risk for adverse obstetric outcomes. Evidence from these studies supports a correlation between maternal chronic conditions and adverse perinatal outcomes, including increased risk for preeclampsia, cesarean section, preterm birth, and admission in the Neonatal Intensive Care Unit (NICU). However, there is a knowledge gap pertaining to the management of these women during lactation. This review aimed at summarizing the available research literature regarding breastfeeding in mothers with chronic diseases. Adjusted and evidence-based support may be required to promote breastfeeding in women with chronic diseases; however, our comprehension of breastfeeding in this subpopulation is still unclear. The literature related to breastfeeding extends in various scientific areas and multidisciplinary effort is necessary to compile an overview of current evidence and knowledge regarding breastfeeding issues in mothers with chronic diseases.

Pitfalls in the assessment of gestational transient thyrotoxicosis

Gestational transient thyrotoxicosis (GTT) is associated with direct stimulation of the maternal thyroid gland by human chorionic gonadotropin (hCG). It is characterized by slightly higher thyroid hormone and lower thyroid-stimulating hormone (TSH) levels in early pregnancy and mild or no symptoms. While GTT must be distinguished from Graves' disease (GD), which is associated with maternal and fetal complications, treated GD and new-onset GD in pregnancy are occasionally challenging to distinguish. Evaluating serum hCG levels and TSH receptor antibody (TRAb) titers can help, but the results are not irrefutable due to pregnancy-related immunosuppression. Moreover, GTT can follow unusual clinical courses in relation to some pregnancy complications. Excessive hCG production can cause severe GTT symptoms in patients with hyperemesis gravidarum, trophoblastic disease, or multiple pregnancies. Thyrotoxicosis can emerge beyond the second trimester in patients with gestational diabetes mellitus and mirror syndrome, because of delayed elevations in the hCG levels. Detailed knowledge about GTT is necessary for correct diagnoses and its appropriate management. This review focuses on the diagnosis of GTT, and, particularly, its differentiation from GD, and unusual clinical conditions associated with GTT that require comprehensive management.

Thyroid dysfunction following pregnancy and implications for breastfeeding

Subclinical autoimmune thyroiditis exacerbates after delivery through immune rebound mechanisms and results in 5 types of thyroid dysfunction. The prevalence of postpartum thyroid dysfunction is around 5% in mothers in the general population. Typically, an exacerbation induces destructive thyrotoxicosis followed by transient hypothyroidism, known as postpartum thyroiditis. Late development of permanent hypothyroidism is found frequently and patients should be followed up once every one to two years. Destructive thyrotoxicosis in postpartum thyroiditis should carefully be differentiated from post-partum Graves' disease. Postpartum thyroiditis typically occurs 1-4 months after parturition whereas Graves' disease develops at 4-12 months postpartum. Anti-TSH receptor antibodies (TRAb) are typically positive and thyroid blood flow is high in Graves' disease, whereas these features are absent in postpartum thyroiditis. Postpartum Graves' disease should be treated with antithyroid drugs.

Role of hypothyroidism and associated pathways in pregnancy and infertility: Clinical insights

Thyroid disorders are the most common endocrine problems in women. In most of the cases, thyroid can lead to infertility or miscarriages. The etiology of infertility is multifactorial with thyroid disorders as the most common presenting factor, hypothyroidism in particular. Infertility in women can lead to emotional and psychological stress. The prevalence of hypothyroidism during pregnancy is estimated to be 0.3%–0.5%. Hypothyroidism and hyperthyroidism can result in menstrual irregularities and anovulatory cycles, thus affecting the fertility. There is a significant high prolactin (PRL) level in infertile women with hypothyroidism when compared to euthyroid patients, indicating the relation between hypothyroidism and hyperprolactinemia. The amount of thyrotropin releasing hormone (TRH) from the hypothalamus is markedly increased by inhibition of pyroglutamyl peptidase II, the enzyme catalyzing TRH. The increased TRH in hypothyroidism causes increased thyroid-stimulating hormone and PRL secretion by pituitary, leading to infertility and galactorrhea. In recent years, a neuropeptide called kisspeptin, encoded by Kiss1 gene, a potent stimulus for GnRH secretion, has been recognized, which suggests a future direction of treatment with kisspeptin and benefits the fertility induction among hyperprolactinemic infertile patients. Untreated hypothyroidism during pregnancy can lead to subfertility, fetal deaths, premature deliveries, and abortions. Therefore, women planning for pregnancy and infertile women should be assessed for thyroid hormones and serum PRL.

Hyperthyroidism in the pregnant woman: Maternal and fetal aspects

Hyperthyroidism during pregnancy is uncommon. Nonetheless, prompt identification and adequate management of hyperthyroidism in a pregnant woman is essential, because uncontrolled thyrotoxicosis significantly increases the risk of maternal and fetal complications. Also, fetal prognosis may be affected by the transplacental passage of maternal thyroid stimulating antibodies or thyrostatic agents, both of which may disrupt fetal thyroid function. Birth defects have been reported in association with the use of antithyroid drugs during early pregnancy. Although rarely, offspring of mothers with Graves’ disease may develop fetal/neonatal hyperthyroidism, the management of which requires a close collaboration between endocrinologists, obstetricians, and neonatologists.

Because of the above considerations, the management of pregnant and lactating women with hyperthyroidism requires special care, bearing in mind that both maternal thyroid excess per se and related treatments may adversely affect the newborn’s health.

In this review we discuss the diagnosis and management of hyperthyroidism in pregnancy, along with the impact of thyrotoxicosis and medications on fetal outcome.