WHY THYROID DISORDERS ARE EXACERBATED BY PREGNANCY
Autoimmune Thyroid Disease in Pregnancy: A Review
Juan C. Galofre, M.D., Ph.D.1,,2 and Terry F. Davies, M.D
In recent years, a number of important studies have been published addressing the special circumstances of thyroid physiology and pathophysiology in the gravid woman. Our increased knowledge has improved the management of pregnant women with a variety of thyroid disorders. This has also resulted in important expanded guidelines for the management of thyroid disease in pregnancy by international thyroid associations.
Maternal thyroid during pregnancy
During pregnancy, several important physiological changes occur, with substantial repercussions for women's thyroid gland. At the same time, maternal thyroid hormones (TH) play a vital role in the development and function of both the fetus and the placenta. Thyroid gland volume usually enlarges during pregnancy, and TH synthesis increases about 50% above the preconception level. These changes are in response to several factors.
The normal pattern of human chorionic gonadotropin (hCG) secretion during pregnancy demonstrates a major increase during the first trimester and a plateau during midgestation, where it persists until shortly after delivery.4 hCG has a much researched thyroid-stimulating hormone (TSH)-like activity secondary to specificity crossover at the TSH receptor (TSHR). As a result, serum thyroxine (T4) and triiodothyronine (T3) levels are elevated, whereas serum TSH levels are reduced. Pregnancy-related hyperestrogenism induces a 100% rise in serum thyroxine-binding globulin (TBG) as a result of changes in TBG half-life secondary to altered glycosylation. As a consequence, by week 10 of gestation, total T4 and T3 serum concentrations are increased and plateau at this level until delivery.4,5 Other physiological adjustments also increase TH synthesis, such as elevation in the maternal glomerular filtration rate (GFR) and transplacental passage of T4.6 These changes mean that adjusted normal reference ranges for thyroid function tests, unique to pregnancy, must be consulted (Figs. 1 and and22).
FIG. 1.Thyroid-stimulating hormone (TSH) serum levels expressed in percentiles according to gestational age. (Adapted from Panesar et al.,7 with permission.)FIG. 2.Variation in serum levels of thyroid function test and pregnancy-related hormones according to course of gestation. TBG, thyroxine-binding globulin; T4, thyroxine; T3, triiodothyronine; hCG, human chorionic gonadotropin; TSH, thyroid-stimulating hormone. ...Immune modifications
For a successful pregnancy outcome, the maternal immune system must tolerate the fetus. Placental trophoblast cells, therefore, not only provide a physical barrier but also secrete a variety of cytokines and hormones, including several immunomodulatory molecules. These secretions induce detectable immune changes, including enhanced regulatory T cell function10,11 (Table 1), which have great importance for many autoimmune diseases. The result is a general improvement in autoimmune intolerance during gestation.12 In addition, taking advantage of this immunosuppressive condition, fetal cells cross the placental barrier and survive maternal intolerance, allowing them to take up residence in maternal tissues while maternal cells settle in the fetus. There is abundant evidence indicating that the thyroid gland is one of the important organs where fetal microchimeric cells may become established.13 The consequences of fetal immune cells within the maternal thyroid gland remain an attractive explanation for the postpartum exacerbation of autoimmune thyroid diseases (AITD), but this influence is far from confirmed.
DEGENERATIVE DISC DISEASE & THYROID DISORDERS
Walking is a healthful exercise but a good walk requires a good back. Thyroid disease can cause problems with the entire body. One area of the body that is not generally considered when discussing thyroid disease is the back. Degenerative disc disease that is caused by the aging process can be enhanced by thyroid disease, which causes the body functions to slow down and thus makes any problem involving pain worse.
Nutritional Advice is Constantly Changing
Treating through nutrition has taken a giant leap forward in the past few years. While 50 years ago it was considered revolutionary for a doctor to recommend Vitamin C, now it's commonplace. We (meaning my wife, Dr. Lisa Lanzisera and I) remember a cardiologist in St. Louis who 30 years ago was rebuked for promoting CoEnzyme Q 10 to his patients. Again, this is now acceptable and widely used.
My point is my wife and I raised a red flag in our book "Wheat Gluten" about how gluten can cause "Leaky Gut" syndrome and be a catalyst for widespread inflammation and autoimmune reactions. The research being conducted around the world continues to support this statement.
Good nutritional advice is not just recommending nutritious foods but avoidance of certain foods as well. For example, whole grains have been recommended to the public for years now. It turns out that whole grains in people who are gluten sensitive are harmful. Gluten sensitivity may be the best known food allergen but there are many others. Fortunately, there are tests that can detect a wide range of food sensitivities.
Treatments involving nutrition and dietary changes have evolved...and continue to do so.