Goitrogenic anions, thyroid-stimulating hormone, and thyroid hormone in infants

BACKGROUND

Environmental exposure of infants to perchlorate, thiocyanate, nitrate, might interfere with thyroid function. U.S. women with higher background perchlorate exposure have higher thyroid-stimulating hormone (TSH) and lower thyroxine (T4). There are no studies with individual measures of thyroid function and these goitrogens available in infants.

OBJECTIVE

We examined the association of urinary perchlorate, nitrate, iodide, and thiocyanate with urinary T4 and TSH in infants and whether that association differed by sex or iodide status.

METHODS

We used data and samples from the Study of Estrogen Activity and Development, which assessed hormone levels of full-term infants over the first 12 months of life. The study included 92 full-term infants between birth and 1 year of age seen up to four times. Perchlorate, thiocyanate, nitrate, and iodide were measured in 206 urine samples; TSH and T4 and were measured in urines and in 50 blood samples.

RESULTS

In separate mixed models, adjusting for creatinine, age, sex, and body mass index, infants with higher urinary perchlorate, nitrate or thiocyanate had higher urinary TSH. With all three modeled, children with higher nitrate and thiocyanate had higher TSH, but higher perchlorate was associated with TSH only in children with low iodide. Unexpectedly, exposure to the three chemicals was generally associated with higher T4.

CONCLUSIONS

The association of perchlorate exposure with increased urinary TSH in infants with low urinary iodide is consistent with previous findings. Higher thiocyanate and nitrate exposure were also associated with higher TSH in infants.

Follicular thyroid cancer cells: a model of metastatic tumor in vitro (review)

We used a thyroid metastatic tumor model to analyze some of the mechanisms of invasion and metastasis in culture. Chronic TSH stimulation (thyroid stimulating hormone) was associated with enhanced tumor proliferation and aggressiveness. We present a unique metastatic tumor model including three follicular thyroid cancer cell lines using a human primary tumor and two metastases of the same patient. They contain thyroglobulin, have intact thyroid functions and response to TSH. Investigating growth factor sensitivity we found that the amplitude of stimulation or inhibition of invasion was significantly smaller in both metastatic cell lines. Unstimulated cells of the lung metastasis had the highest basal invasive potential, but were only minimally affected by the stimulation of growth factors. In contrast, the parental cell line had the lowest basal invasiveness, but was considerably stimulated by growth factors.