Does human chorionic gonadotropin have human thyrotropic activity in vivo?

Mild iodine deficiency in pregnancy in Europe and its consequences for cognitive and psychomotor development of children: a review

Despite the introduction of salt iodization programmes as national measures to control iodine deficiency, several European countries are still suffering from mild iodine deficiency (MID). In iodine sufficient or mildly iodine deficient areas, iodine deficiency during pregnancy frequently appears in case the maternal thyroid gland cannot meet the demand for increasing production of thyroid hormones (TH) and its effect may be damaging for the neurodevelopment of the foetus. MID during pregnancy may lead to hypothyroxinaemia in the mother and/or elevated thyroid-stimulating hormone (TSH) levels in the foetus, and these conditions have been found to be related to mild and subclinical cognitive and psychomotor deficits in neonates, infants and children. The consequences depend upon the timing and severity of the hypothyroxinaemia. However, it needs to be noted that it is difficult to establish a direct link between maternal iodine deficiency and maternal hypothyroxinaemia, as well as between maternal iodine deficiency and elevated neonatal TSH levels at birth. Finally, some studies suggest that iodine supplementation from the first trimester until the end of pregnancy may decrease the risk of cognitive and psychomotor developmental delay in the offspring.

Iodine and thyroid hormones during pregnancy and postpartum

Iodine is a trace element essential for synthesis of the thyroid hormones, triiodothyronine and thyroxine. These hormones play a vital role in the early growth and development stages of most organs, especially the brain. The World Health Organization (WHO) has declared that, after famine, iodine deficiency is the most avoidable cause of cerebral lesions including different degrees of mental retardation and cerebral paralysis. The main function of iodine in vertebrates is to interact with the thyroid hormones. During pregnancy sufficient quantities of iodine are required to prevent the appearance of hypothyroidism, trophoblastic and embryonic or fetal disorders, neonatal and maternal hypothyroidism, and permanent sequelae in infants. Thyroid hormone receptors and iodothyronine deiodinases are present in placenta and central nervous tissue of the fetus. A number of environmental factors influence the epidemiology of thyroid disorders, and even relatively small abnormalities and differences in the level of iodine intake in a population have profound effects on the occurrence of thyroid abnormalities. The prevalence of disorders related to iodine deficit during pregnancy and postpartum has increased. Iodine supplementation is an effective measure in the case of pregnant and lactating women. However, it is not implemented and the problem is still present even in societies with theoretically advanced health systems. During pregnancy and postpartum, the WHO recommends iodine intake be increased to at least 200 microg/day. Side-effects provoked by iodine supplementation are rare during pregnancy at the recommended doses.

The human chorionic gonadotropin molecule from patients with trophoblastic diseases has a high thyrotropic activity but is less active in the ovary

To examine the pathogenesis of hyperthyroidism in women with trophoblastic diseases, the biological activity of human chorionic gonadotropin (hCG) molecules in women with normal pregnancy (n = 85) and in women with trophoblastic diseases (vesicular mole, n = 30; and choriocarcinoma, n = 12) was compared. Hyperthyroidism (thyroid stimulating hormone (TSH) < 0.3 mIU/l) was observed more frequently in women with trophoblastic diseases. All the sera were then subjected to Chinese hamster ovary cells transfected with the human TSH receptor (CHO-hTSHr cells) and cAMP production was compared. Sera from the women with choriocarcinoma showed the highest cAMP production. Interestingly, significant correlation between serum hCG level and cAMP production in CHO-hTSHr cells was observed only in women with trophoblastic disease. All the sera were then applied to CHO cells transfected with hCG/luteinizing hormone (LH) receptor (CHO-hCG/LHr cells). In contrast to the findings with the TSH receptor, sera from the women with normal pregnancy showed the highest cAMP production in these cells. Correlation between serum hCG level and cAMP production in CHO-hCG/LHr cells was significant only in normal pregnancy. These results indicate that the hCG molecule from women with trophoblastic diseases displays enhanced thyrotropic activity.

The relationship between thyroxine, oestradiol, and postnatal alopecia, with relevance to women's health in general

Post-partum hair loss is possibly due to a reduction in the levels of oestradiol and thyroxine postnatally. Alopecia and/or a persistent loss of hair condition postnatally is associated with a group of symptoms (a syndrome), wherein postnatal depression is significant, as a result of physiologically inadequate levels of thyroxine (T4) and oestradiol (E2), secondary to physiological postnatal anterior pituitary dysfunction. Using this hypothesis, the author began to apply the same hypothesis to other female patients, who were not postpartum, but with similar symptomatology. The author became aware of the necessity for an adequate level of T4 to be present for correct oestrogenization to occur. He then goes on to hypothesize on the synergistic relationship that T4 and oestradiol may have in premenstrual syndrome (PMS), infertility, dysfunctional uterine bleeding, poor placental function, osteoporosis, and anorexia nervosa. He also discusses the role lowering T4 could play in the treatment of terminal cancer breast in premenopausal women.

A T2S cross-reactive material (compound W) in hyperthyroid patients with trophoblastic disease

In a previous study we observed increased serum levels of a 3,3'-diiodothyronine sulfate (T2S)-like material (compound W) in women who received human chorionic gonadotropin (hCG) treatment. In the present study we assessed serum compound W values in 113 women (total serum sample: 190) with trophoblastic disease, in 7 normal nonpregnant women during the menstrual cycle and 7 women given hCG treatment in the course of in vitro fertilization. Fifty-three women with trophoblastic disease had serum free thyroxine (FT4) concentrations greater than 3.0 ng/dL with suppressed serum thyrotropin (TSH) levels; 61 had FT4 values less than 3.0 ng/dL with a mean TSH of 0.83 mU/L. Mean (+/- SE) compound W concentrations in the high FT4 group were significantly higher than in the low FT4 group (76 +/- 8.1 vs. 21 +/- 1.7 ng T2S equivalent, p < 0.001) There were significant correlations between serum hCG and compound W concentrations (r = 0.472, p < 0.001), serum FT4 and hCG (r = 0.503, p < 0.0001) and serum FT4 and compound W (r = 0.585, p < 0.0001). In nonpregnant women serum compound W levels increased from 7.5 +/- 8 ng/dL at the end of the menstrual period to 15 +/- 1.7 ng/dL 21 days after the last menstrual period. Finally, a single dose of hCG (10,000 USP units, intramuscularly) increased mean (+/- SE) serum compound W levels from 12.8 +/- 2.3 to 64 +/- 9.7 ng/dL and 54 +/- 12 ng/dL at 9 and 16 days, respectively. These results indicate that hCG and perhaps luteinizing hormone (LH) increase serum compound W concentrations in women. The mechanism and significance presently are unclear.