Showing papers by "Elizabeth N. Pearce published in 2007"

Breast milk iodine and perchlorate concentrations in lactating Boston-area women.

Abstract: Context: Breastfed infants rely on adequate maternal dietary iodine intake. Objective: Our objective was to measure breast milk iodine and perchlorate, an inhibitor of iodide transport into the thyroid and potentially into breast milk, in Boston-area women. Participants: The study included 57 lactating healthy volunteers in the Boston area. Measurements: Breast milk iodine and perchlorate concentrations and urine iodine, perchlorate, and cotinine concentrations were measured. For comparison, iodine and perchlorate levels in infant formulae were also measured. Results: Median breast milk iodine content in 57 samples was 155 μg/liter (range, 2.7–1968 μg/liter). Median urine iodine was 114 μg/liter (range, 25–920 μg/liter). Perchlorate was detectable in all 49 breast milk samples (range, 1.3–411 μg/liter), all 56 urine samples (range, 0.37–127 μg/liter), and all 17 infant formula samples (range, 0.22–4.1 μg/liter) measured. Breast milk iodine content was significantly correlated with urinary iodine per gram ...

A genome-wide association for kidney function and endocrine-related traits in the NHLBI's Framingham Heart Study

Abstract: Glomerular filtration rate (GFR) and urinary albumin excretion (UAE) are markers of kidney function that are known to be heritable. Many endocrine conditions have strong familial components. We tested for association between the Affymetrix GeneChip Human Mapping 100K single nucleotide polymorphism (SNP) set and measures of kidney function and endocrine traits. Genotype information on the Affymetrix GeneChip Human Mapping 100K SNP set was available on 1345 participants. Serum creatinine and cystatin-C (cysC; n = 981) were measured at the seventh examination cycle (1998–2001); GFR (n = 1010) was estimated via the Modification of Diet in Renal Disease (MDRD) equation; UAE was measured on spot urine samples during the sixth examination cycle (1995–1998) and was indexed to urinary creatinine (n = 822). Thyroid stimulating hormone (TSH) was measured at the third and fourth examination cycles (1981–1984; 1984–1987) and mean value of the measurements were used (n = 810). Age-sex-adjusted and multivariable-adjusted residuals for these measurements were used in association with genotype data using generalized estimating equations (GEE) and family-based association tests (FBAT) models. We presented the results for association tests using additive allele model. We evaluated associations with 70,987 SNPs on autosomes with minor allele frequencies of at least 0.10, Hardy-Weinberg Equilibrium p-value ≥ 0.001, and call rates of at least 80%. The top SNPs associated with these traits using the GEE method were rs2839235 with GFR (p-value 1.6*10-05), rs1158167 with cysC (p-value 8.5*10-09), rs1712790 with UAE (p-value 1.9*10-06), and rs6977660 with TSH (p-value 3.7*10-06), respectively. The top SNPs associated with these traits using the FBAT method were rs6434804 with GFR(p-value 2.4*10-5), rs563754 with cysC (p-value 4.7*10-5), rs1243400 with UAE (p-value 4.8*10-6), and rs4128956 with TSH (p-value 3.6*10-5), respectively. Detailed association test results can be found at http://www.ncbi.nlm.nih.gov/projects/gap/cgi-bin/study.cgi?id=phs000007 . Four SNPs in or near the CST3 gene were highly associated with cysC levels (p-value 8.5*10-09 to 0.007). Kidney function traits and TSH are associated with SNPs on the Affymetrix GeneChip Human Mapping 100K SNP set. These data will serve as a valuable resource for replication as more SNPs associated with kidney function and endocrine traits are identified.

National trends in iodine nutrition: is everyone getting enough?

Abstract: Iodine deficiency is an important public health problem worldwide. Until the 1920s, endemic iodine deficiency disorders were prevalent in the Great Lakes, Appalachian, and Northwestern regions of the United States. Iodized salt was responsible for eliminating endemic goiter in the United States and remains the mainstay of iodine deficiency disorder eradication efforts worldwide. Although urinary iodine values have decreased by 50% since the early 1970s, the United States remains iodine sufficient. However, U.S. iodine nutrition, particularly among women of childbearing age, may remain an area worthy of public health concern. There is a wide amount of variation in the iodine content of some common foods, and the iodine content of foods is not well reflected by package labeling. There needs to be increased awareness of the importance of adequate iodine nutrition, particularly during pregnancy and lactation, among the U.S. public.

Thyroid dysfunction in perimenopausal and postmenopausal women.

Abstract: Thyroid dysfunction is common, especially among women over the age of 50. In caring for peri- and post-menopausal women, it is important to recognize the changing clinical manifestations of thyroid disease with age. Postmenopausal women are at increased risk of both osteoporosis and cardiovascular disease, and untreated thyroid disease may exacerbate these risks. Screening for thyroid dysfunction in asymptomatic individuals is controversial, but aggressive case-finding should be pursued, especially in older women. Women with overt thyroid dysfunction should be treated. Therapy for women with subclinical thyroid dysfunction is more controversial, although women with levels of thyroid stimulating hormone (TSH) > or =10 mU/L should be treated, and treatment may be considered in symptomatic women with subclinical hypothyroidism and TSH values <10 mU/L, and in women with subclinical hyperthyroidism who have TSH values consistently <0.1 mU/L. In women who are treated with thyroxine, careful dose titration and monitoring are required in order to prevent the adverse consequences of iatrogenic subclinical hyperthyroidism or hypothyroidism. Finally, caution is required in diagnosing and treating thyroid dysfunction in women who are taking oral estrogens or selective estrogen receptor modulators.

Assessment of thyroid function and urinary and breast milk iodine concentrations in healthy newborns and their mothers in Tehran.

Abstract: The objective was to measure breast milk iodine (MI) and urinary iodine (UI) concentrations in healthy newborns and their nursing mothers from an iodine-sufficient region to determine adequacy and to relate these parameters to thyroid function tests in mothers and infants. The design of the study was cross-sectional. Forty-eight healthy neonates of 37 to 42 weeks gestation with normal cord blood TSH values and their mothers were recruited in Tehran Iran. Serum thyroid function tests were performed and maternal and infant urinary iodine excretion and maternal MI concentration were measured. Neonatal age was 12.9 +or- 3.9 (mean +or- SD; range 7-30) days and maternal age was 25.8 +or- 5 years. Median (range) UI in neonates was 271 µg/l (57-800) and in mothers was 107 µg/l (20-710). Median (range) MI was 148 µg/l (45-750). Neonatal and maternal UI did not correlate with serum thyroid function tests. UI 230 µg/l was found in 20 12.5 and 67.5% of neonates and 79.1 14 and 7%of mothers respectively. MI was 180 µg/l in 52.4 11.9 and 35.7% of mothers respectively. Among euthyroid neonates UI was adequate despite low median maternal UI and MI concentrations. There were no significant correlations between UI or MI and thyroid function tests in the mothers and infants. (authors)

A dietary iodine questionnaire: correlation with urinary iodine and food diaries.

Abstract: Objective: It has been difficult to determine the sources of U.S. dietary iodine. This study was designed to validate a self-administered questionnaire about dietary iodine sources. Design: We constructed a questionnaire to assess iodine intake in 46 healthy Boston-area adult volunteers. Questionnaire information was correlated with subjects' 24-hour food diaries. Spot morning urine cotinine (a metabolite of nicotine from cigarette smoking) and iodine concentrations were measured. Main outcomes: 91% of 46 subjects were women [mean (± SD) age of 38 (± 10) years]. Information from 24-hour food diaries correlated well with questionnaire data. The median urinary iodine concentration (UIC) was 140 μg/L (range: 18–845 μg/L). There were significant positive associations between intake of yogurt (n = 9, p = 0.01) and saltwater fish (n = 6, p = 0.0003), and an inverse correlation between bagels (n = 5, p = 0.0006) and UIC. We found no associations between self-reported milk, iodized salt, tobacco use, or urinary c...

The effect of type of delivery and povidone-iodine application at delivery on cord dried-blood-specimen thyrotropin level and the rate of hyperthyrotropinemia in mature and normal-birth-weight neonates residing in an iodine-replete area: report of Tehran Province, 1998-2005.

Abstract: Objective: To evaluate the effects of delivery type and of povidone-iodine disinfection at delivery on cord dried-blood-specimen (DBS) thyrotropin (TSH) concentrations. Methods: From 1998 to 2005, cord DBSs were collected from live deliveries in Tehran and Damavand, and TSH was assayed by a two-site immunoradiometric assay. Hyperthyrotropinemia was defined as TSH ≥20 mU/L. Vaginal deliveries prepared with povidone-iodine (VGL-PVP-I) or chlorhexidine (VGL-CHL), and cesarean sections prepared with povidone-iodine (CS-PVP-I) disinfection were assessed. Full-term, normal-size newborns were included. Iodine concentrations were measured in urine samples collected from 132 pregnant women immediately prior to delivery. Results: Median (range) TSH was 5.3 (1.0 to >100) mU/L in VGL-PVP-I (n = 23,432), 5.3 (1.0 to >100) mU/L in VGL-CHL (n = 5658), and 5.0 (1.0 to >100) mU/L in CS-PVP-I (n = 19,016) (p < 0.0001). Median TSH was higher in VGL-PVP-I versus CS-PVP-I (p < 0.0001) and in VGL-CHL versus CS-PVP-I (p < 0.000...