ABSTRACT
Thyroid function in early pregnancy has been reported to be slightly different from that in second or third trimester. We assessed thyroid function before and after induced abortion in normal pregnant women. A significant increase in serum Free T4 and a decrease in serum TSH were observed before abortion and these changes, apart from the contemporary significance of serum hCG-beta, were especially marked in pregnant women with nausea and vomiting. On the other hand, an increased level of Free T4 and a reduced level of TSH returned to the normal ranges 7-10 days after induced abortion. Furthermore, serum hCG-beta was significantly reduced. These results suggest that, in normal early pregnancy, thyroid function may be related to serum hCG-beta concentration and its increased level, which induces gestational emesis.
PIP: At the Institutes of Gynecology and Obstetrics of the University of Rome (La Sapienza), Italy, serum levels of free thyroxine (FT4), FT3, thyroid stimulating hormone (TSH), and the beta subunit of human chorionic gonadotropin (hCG-beta) were compared before and 7-10 days after induced abortion in 19 normal women in their first trimester of pregnancy. The women were divided into those with nausea and vomiting (7) and those without these symptoms (12). The aim was to distinguish slight transient hyperthyroidism associated with nausea and vomiting in normal early pregnancy with pre-existing thyrotoxicosis or hyperemesis gravidarum. In both groups of women, serum hCG-beta levels were significantly lower 7-10 days after the induced abortion than before (p 0.01) while serum TSH levels were significantly higher (p 0.02). The serum levels of FT4 were higher before than after abortion in both groups of women, but were significantly so in women with nausea and vomiting (p 0.001). After induced abortion, serum levels of FT4 and TSH returned to normal levels. Earlier research found that hCG peaks at 10-13 weeks gestation and decreases to a stable level by 20 weeks gestation and that hCG is associated with thyroid hormone levels. This study's findings support those of earlier research since women in the nausea and vomiting group had higher levels of FT4 and hCG-beta and lower levels of TSH before the induced abortion than after it. Perhaps, hCG physiologically activates the thyroid gland in early pregnancy, which may in turn induce vomiting during early pregnancy.
