Antenatal Thyroid Screening and Childhood Cognitive Function
ABSTRACT Children born to women with low thyroid hormone levels have been reported to have decreased cognitive function.
We conducted a randomized trial in which pregnant women at a gestation of 15 weeks 6 days or less provided blood samples for measurement of thyrotropin and free thyroxine (T(4)). Women were assigned to a screening group (in which measurements were obtained immediately) or a control group (in which serum was stored and measurements were obtained shortly after delivery). Thyrotropin levels above the 97.5th percentile, free T(4) levels below the 2.5th percentile, or both were considered a positive screening result. Women with positive findings in the screening group were assigned to 150 μg of levothyroxine per day. The primary outcome was IQ at 3 years of age in children of women with positive results, as measured by psychologists who were unaware of the group assignments.
Of 21,846 women who provided blood samples (at a median gestational age of 12 weeks 3 days), 390 women in the screening group and 404 in the control group tested positive. The median gestational age at the start of levothyroxine treatment was 13 weeks 3 days; treatment was adjusted as needed to achieve a target thyrotropin level of 0.1 to 1.0 mIU per liter. Among the children of women with positive results, the mean IQ scores were 99.2 and 100.0 in the screening and control groups, respectively (difference, 0.8; 95% confidence interval [CI], -1.1 to 2.6; P=0.40 by intention-to-treat analysis); the proportions of children with an IQ of less than 85 were 12.1% in the screening group and 14.1% in the control group (difference, 2.1 percentage points; 95% CI, -2.6 to 6.7; P=0.39). An on-treatment analysis showed similar results.
Antenatal screening (at a median gestational age of 12 weeks 3 days) and maternal treatment for hypothyroidism did not result in improved cognitive function in children at 3 years of age. (Funded by the Wellcome Trust UK and Compagnia di San Paulo, Turin; Current Controlled Trials number, ISRCTN46178175.).
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ABSTRACT: Iodine is an essential trace element for the synthesis of thyroid hormones, which are keys in maternal metabolism during pregnancy as well as in neurological development during fetal and postnatal life. This was a prospective study on iodine status and thyroid function in women during pregnancy in the Basque country to assess whether there was any relationship among maternal urinary iodine, maternal thyroid function and thyrotropin (TSH) in newborns, and to explore any difference in women experiencing miscarriages. We analyzed TSH, free T4 (FT4), free T3 (FT3), thyroid peroxidase antibody (TPO-Ab) titers in serum and urinary iodine concentrations (UIC) in 2104 women in the first trimester of pregnancy and in 1322 of them in their second trimester. We obtained neonatal TSH levels in 1868 cases. In the first (T1) and second trimesters (T2), the median UICs were 88.5μg/L and 140μg/L, respectively. No relationship was found between UIC and FT4, or maternal and neonatal TSH. In T1 and T2, 9.7% and 7.5% of women were TPO-Ab positive, respectively. The total miscarriage rate was 10%. The percentage of miscarriages in healthy women was 8.9%, lower than in women with overt hypothyroidism (21.2%; p<0.001) and than in women with subclinical hypothyroidism (15.6%; p<0.025). The miscarriage rate was not higher in TPO-Ab-positive women. In this study most women had iodine deficiency during pregnancy. Neonatal TSH is not correlated with maternal UIC during pregnancy. Pregnant women with hypothyroidism have a higher rate of miscarriages.Journal of Trace Elements in Medicine and Biology 07/2013; DOI:10.1016/j.jtemb.2013.07.002 · 2.49 Impact Factor
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ABSTRACT: 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.Journal of Trace Elements in Medicine and Biology 02/2013; 27(3). DOI:10.1016/j.jtemb.2013.01.002 · 2.49 Impact Factor
Article: Use and misuse of thyroid hormone[Show abstract] [Hide abstract]
ABSTRACT: Synthetic thyroxine has replaced animal thyroid gland extract as the preferred drug in chronic thyroid hormone replacement. Synthetic thyroxine monotherapy is used to treat overt primary and secondary hypothyroidism, and some cases of subclinical hypothyroidism. In addition, thyroid-stimulating hormone suppressive therapy with thyroxine is a component of the chronic treatment for differentiated thyroid carcinoma. Liothyronine, however, is conventionally for short-term usage, including thyroid hormone withdrawal preparation for radioactive iodine scanning and treatment of differentiated thyroid carcinoma and some cases of myxoedema coma. On very rare occasions where patients are apparently intolerant of or unresponsive to thyroxine, liothyronine may be used chronically. However, there is controversy concerning the use of alternative regimens of thyroid hormone, such as the use of thyroxine-liothyronine combination and thyroid extracts. Thyroid hormone has also been misused to promote weight loss and treat 'symptomatic' biochemically euthyroid patients. There is insufficient evidence to support the use of thyroid hormone to improve treatment response in depression and severe non-thyroidal illnesses.Singapore medical journal 07/2013; 54(07):406-410. DOI:10.11622/smedj.2013143 · 0.63 Impact Factor