The thyroid gland becomes more active during pregnancy to meet the hormonal needs of both mother and baby, according to endocrinologists Suemi Marui and Rosa Paula Biscolla, who discussed the topic on the program CNN Sinais Vitais with Dr. Kalil.
Marui, who heads the Thyroid Unit at the Hospital das Clinicas of the University of Sao Paulo's medical school (FMUSP), said the gland is stimulated by the hormone HCG, which is produced by the placenta and can cause visible growth of the thyroid.
A historic sign of pregnancy
Marui illustrated how dramatic this change can be with a historical detail: before modern pregnancy tests existed, some women would wear a string around their neck and realize they were pregnant when it grew tighter, a sign that their thyroid had enlarged.
She said the thyroid grows during gestation because the body needs the hormone for both the mother and the baby, and that it is stimulated by HCG produced in the placenta.
Iodine supplementation in pregnancy
Biscolla, an endocrinologist and professor at the Escola Paulista de Medicina, part of the Federal University of Sao Paulo (EPM/UNIFESP), noted that a recent guideline from the American Thyroid Association recommends iodine supplementation for women who are trying to conceive or who are already pregnant.
However, she said that recommendation does not directly apply to Brazil. She said Brazil is a country with sufficient iodine, since salt there is iodized by law.
According to Biscolla, supplementation would only be relevant for patients on iodine-restricted diets, such as vegans, people with high blood pressure, or those with severe heart failure who consume very little salt or processed foods.
Marui added that vitamin supplements typically prescribed to pregnant women already contain a small amount of iodine, enough to cover any deficiency.
She also issued a warning about the use of Lugol's solution, a preparation with a high iodine content, during pregnancy. She said it causes an excess of iodine that passes from the mother to the baby, causing the fetus's thyroid to stop functioning, which she said is not good.
Thyroid disease and menopause
The specialists also discussed the link between menopause and thyroid disease. They said common menopausal symptoms, including memory changes, weight gain, irritability and hot flashes, can easily be mistaken for hypothyroidism or hyperthyroidism.
Biscolla noted that this age group also has a higher incidence of thyroid disease, which makes distinguishing between the two conditions more challenging. For that reason, the specialists recommend that thyroid function be checked during menopause.
