The sensitivity and specificity of thyroglobulin concentration using repeated measures of urinary iodine excretion

Purpose

Iodine deficiency affects 30% of populations worldwide. The amount of thyroglobulin (Tg) in blood increases in iodine deficiency and also in iodine excess. Tg is considered as a sensitive index of iodine status in groups of children and adults, but its usefulness for individuals is unknown. The aim of this study was to determine the diagnostic performance of Tg as an index of iodine status in individual adults.

Methods

Adults aged 18–40 years (n?=?151) provided five spot urine samples for the measurement of urinary iodine concentration expressed as μg/L (UIC), μg/g of creatinine (I:Cre), and μg/day (estimated UIE); the mean of the five samples was used as the reference standard. Participants also provided a blood sample for the determination of Tg, thyroid-stimulating hormone (TSH), and free thyroxine (FT4).

Results

The median of UIC, I:Cre, estimated UIE, and Tg was 72 (range 16–350) μg/L, 90 (range 33–371) μg/g, 129 (range 41–646) μg/day, and 16.4 (range 0.8–178.9) μg/L, respectively. Using Tg cut-offs of >10, >11, >13, and >15 μg/L, the sensitivity and specificity for UIC, I:Cre, and estimated UIE ranged from 52 to 79% and 20–48%, respectively, below the acceptable value of ≥80%. Furthermore, receiver-operating characteristic (ROC) curves for Tg using the three measurements of urinary iodine were situated close to the chance line and the area under the curve ranged from 0.49 to 0.52.

Conclusions

The results from this cross-sectional study indicate that Tg has low sensitivity and specificity to repeated measures of urinary iodine excretion. Further studies are still needed to investigate the usefulness of Tg as a biomarker of individual iodine status.

     

Are breast-fed infants and toddlers in New Zealand at risk of iodine deficiency?

OBJECTIVE: This study assessed the iodine status of New Zealand infants and toddlers and explored factors that might influence their iodine status. METHODS: A community-based, cross-sectional survey of 6- to 24-mo-old children was conducted in three cities in the South Island of New Zealand. Iodine status was determined by a casual urine sample. Breast-feeding mothers were asked to provide a breast milk sample for iodine determination. Caregivers collected a 3-d weighed diet record from their children to investigate associations between dietary patterns and urinary iodine excretion. RESULTS: The median urinary iodine concentration for the group (n = 230) was 67 microg/L (interquartile range 37-115) with 37% (95% confidence interval 30.5-43.4) of children having a urinary iodine concentration lower than 50 microg/L. When children were classified by current feeding method, those children who were currently formula-fed had a significantly higher median urinary iodine concentration (99 microg/L) than did children who were currently breast-fed (44 microg/L; P < 0.000). The mean iodine concentration in breast milk was 22 microg/L (n = 39). After multivariate analysis using estimates from 3-d diet records, only percentage of energy from infant formula was significantly associated with urinary iodine concentration (P = 0.005). CONCLUSIONS: This study found mild iodine deficiency in a group of New Zealand infants and toddlers. Children who consumed infant formula, which is fortified with iodine, had better iodine status than did children who were currently breast-fed because breast milk contained low levels of iodine.     

Is Gippsland environmentally iodine deficient? Water iodine concentrations in the Gippsland region of Victoria,Australia

Objective: This paper provides evidence of environmental iodine deficiency in the Gippsland region. Design: Quantitative study; water samples were collected from 18 water treatment plants and four rain water tanks across Gippsland and water iodine concentrations were measured. Setting: Gippsland region of Victoria, Australia. Main outcome measures: This paper reports on the iodine concentration of drinking water from sources across Gippsland and examines the contribution of iodine from water to the Gippsland diet. This study also briefly examines the relationship between the concentration of iodine in water and distance from the sea. The cut‐off value for water iodine concentrations considered to be indicative of environmental iodine deficiency is <2 µg L^?1. Results: The mean iodine concentration of water from 18 Gippsland water treatment plants was 0.38 µg L^?1 and would therefore make negligible difference to the dietary intake of iodine. This finding also falls well below the suggested dietary intake of iodine from water estimated by the 22nd Australian Total Diet Study. Our study found no linear relationship between the water iodine concentration and distance from the sea. Conclusion: As Gippsland has environmental iodine deficiency there is a greater probability that people living in this region are at higher risk of dietary iodine deficiency than those living in environmentally iodine sufficient regions. Populations living in areas known to have environmental iodine deficiency should be monitored regularly to ensure that problems of iodine deficiency, especially amongst the most vulnerable, are addressed promptly.     

Swiss pilot study of individual seasonal fluctuations of urinary iodine concentration over two years: is age-dependency linked to the major source of dietary iodine?

OBJECTIVE: Because of known significant seasonal fluctuations of iodine concentration in cow's milk (ICM) in Switzerland (winter/summer (w/s) ICM ratio averages 5.6), we looked for seasonal variations and familial aspects in urinary iodine and sodium concentrations (UIC, UNaC). DESIGN:: Prospective sequential cohort investigation. SETTING: University hospital. SUBJECTS: Thirteen children (six girls, seven boys) aged 3-10 y and their parents (n=9) aged 30-47 y. INTERVENTIONS: The volunteers collected 1729 spot urine samples (5.1996-5.1998). UIC data from winter (UIC(w): December-February) and summer seasons (UIC(s): July-September) were compared with UNaC and average milk consumption. Iodine intakes from milk and salt were modelized. RESULTS: Highest seasonal fluctuations of UIC were found in six pre-school children (w/s UIC group average=1.56, significant), followed by seven school children (w/s UIC group average=1.24, N.S.); none existed in adults. UIC/UNaC showed corresponding seasonal fluctuations in children, but not in adults. Winter milk was an important iodine source for children, as proven indirectly by similar seasonal fluctuations of ICM, UIC, UIC/UNaC and an important part within UIC due to milk. CONCLUSIONS: Contribution to UIC from milk intake during winter was high in children (40-50%) and lower in adults (about 20%). Compared with children, dietary habits of adults are more complex and their iodine supply depends mainly on iodized salt and not on milk, so the effect of seasonal ICM variations on UIC is less marked. Because of significant seasonal UIC fluctuations in consumers of fresh milk products in Switzerland, results of future UIC studies conducted during summer and winter seasons should be compared cautiously, especially in young children. Furthermore, consumption of milk is to be promoted, since, besides calcium and vitamins, it is an essential source of iodine. UNaC determination should be included in epidemiologic studies if the dietary source of iodine is questioned.     

Dose and time-dependent hypercholesterolemic effects of iodine excess via TRβ1-mediated down regulation of hepatic LDLr gene expression

Background  

With the global improvement of iodine nutrition, iodine excess is emerging as a new concern.     

Assessment of iodine content of dietary salt in Abidjan (Côte d'Ivoire)

C?te d'Ivoire is one of the countries engaged in the strategy of universal salt iodization set up to prevent and control iodine deficiency disorders. However, no systematic monitoring of iodine content of salt has been performed up to now. Therefore, a survey was conducted on a random sample of 400 households in the Marcory district of Abidjan in order to study consumers' behaviour regarding the purchase and storage of salt, and to determine the iodine content of dietary salt. The proportioning of iodine was carried out by the titrimetric method. The salt consumed in the homes was bought at the market, the shop, the supermarket or was delivered at residence by a hawker in the proportions of 82.8%, 10.3%, 6.3%, and 0.8%, respectively. At the warehouse, the salt purchased was packaged into bags of 25 kg for 0.5% of homes. 1% of homes bought salt in tins. 9.5% of homes bought their salt in sachets. Most homes (89%) replenished their stock in bulk from the market. Laboratory analyses showed that all salt samples were iodised. The average content of iodine in salt was 52.74 ppm with a standard deviation of 32.56. We observed that in 23.3% of households the iodine content of salt was weak (< 30 ppm). Contents higher than the upper limit of normality (30-50 ppm) were found in 44.8% of cases. The level of iodine was adequate for 32% of households. The major risk to which the population is exposed is the outbreak of iodine-induced hyperthyroidism (IIH) despite the fact that the Abidjan area is not naturally deprived of iodine. The risk is even more significant in the goitre endemic zone of the western and northern areas of the country, because these regions receive the same salt as Abidjan. From this arises the need for setting up an effective system of controlling the iodine content in dietary salt to continuously adjust it, taking into consideration the minimum needs of the population.     

Iron status influences the efficacy of iodine prophylaxis in goitrous children in Côte d'Ivoire

In the developing countries of Africa, many children are at high risk for both goiter and iron-deficiency anemia (IDA). Because iron (Fe) deficiency can have adverse effects on thyroid metabolism, Fe deficiency may influence response to supplemental iodine in areas of endemic goiter. Therefore, our aims were to determine: 1) if goitrous children also suffering from IDA could respond to oral iodine supplementation; and 2) if Fe supplementation in goitrous children with IDA would improve their response to oral iodized oil and iodized salt. First, we compared the efficacy of oral iodized oil in two groups of goitrous children: a nonanaemic group vs. an IDA group. The therapeutic response to iodized oil was impaired in the goitrous children with IDA. Second, an open trial of Fe treatment in goitrous children with IDA improved their response to oral iodized oil. Finally, in a randomized double-blind trial, goitrous, Fe-deficient children consuming iodized salt were given Fe supplementation or placebo. Fe supplementation improved the efficacy of the iodized salt. In these studies, both anatomic (thyroid size) and biochemical (TSH, T4) measures indicated that iodine significantly improved thyroid function in the nonanaemic children compared to the Fe deficient children. Iodine was less efficacious in children with lower Hb at baseline and in those with a poorer response to Fe. The data suggest that a high prevalence of IDA among children in areas of endemic goiter may reduce the effectiveness of iodine prophylaxis.     

High prevalence of goiter in an iodine replete area: do thyroid auto-antibodies play a role?

INTRODUCTION: Despite long standing iodine supplementation in Iran the prevalence of goiter remains high in some areas. This may suggest that causes other than iodine deficiency, such as autoimmune thyroid diseases, should also be considered. We therefore assessed the prevalence of anti-thyroid antibodies in children living in an inland area in Iran and correlated these findings with prevalence of goiter within this region. METHODS: In a cross-sectional study, 1948 students were selected by multistage random cluster sampling from the 108 primary schools (age, 7-13 year-old) of the urban and rural areas of Semirom. After obtaining written consent from their parents, the children were examined by endocrinologists for goiter grading. Grade 2 goitrous children (108 cases) were compared with non-goitrous children (111 children as control group) for anti-thyroid antibodies. RESULTS: Overall, 36.7% of 1948 students had goiter. The mean urinary iodine excretion level was 1.49+/-0.7 micromol/L. This was within normal limits. Of 219 children studied, 4.3% presented with subclinical hypothyroidism, and 7.3% had positive anti-thyroid antibodies. There was non-significant difference of positive thyroperoxidase antibody (anti-TPO) (Odds Ratio= 3.2, p= 0.13) but significant difference of anti Tg between goitrous and non goitrous children (Odds Ratio: 5.6, 95% CI: 1.18-26.0, p: 0.015). CONCLUSION: This study suggests that autoimmunity may be one of the mechanisms responsible for goiter persistence after iodine replenishment in this iodine deficient region, but the role of other factors should also be considered.     

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Length of maternity leave and health of mother and child – a review

Summary Objectives: Assessment of the literature on the length of maternity leaves and health of mothers and children; evaluation of the Swiss situation in view of the maternity leave policy implemented in 2005. Methods: Review of thirteen original studies identified by PubMed using topic-related terms. Results: A positive association was shown between the length of maternity leave and mother’s mental health and duration of breastfeeding. Extended maternity leaves were also associated with lower perinatal, neonatal and post-neonatal mortality rates as well as lower child mortality; however, results are obtained in ecological studies. There is less evidence regarding other health outcomes. The new policy in Switzerland extends maternity leave for a considerable number of women to 14 weeks. With this prolongation, fewer depressive symptoms and longer breastfeeding duration can be expected, while benefits regarding other health outcomes would warrant longer leaves. Conclusions: Longer maternity leaves are likely to produce health benefits. The new policy in Switzerland will probably improve the situation of those women, who previously were granted only minimal leave and/or mothers with additional social risk factors. Submitted: 21 October 2005; Revised: 10 October 2006; Accepted: 5 December 2006     

Older Adults’ Use of Online and Offline Sources of Health Information and Constructs of Reliance and Self-Efficacy for Medical Decision Making

We know little about older adults' use of online and offline health information sources for medical decision making despite increasing numbers of older adults who report using the Internet for health information to aid in patient–provider communication and medical decision making. Therefore we investigated older adult users and nonusers of online and offline sources of health information and factors related to medical decision making. Survey research was conducted using random digit dialing of Florida residents' landline telephones. The Decision Self-Efficacy Scale and the Reliance Scale were used to measure relationships between users and nonusers of online health information. Study respondents were 225 older adults (age range = 50?92 years, M = 68.9, SD = 10.4), which included users (n = 105) and nonusers (n = 119) of online health information. Users and nonusers differed in frequency and types of health sources sought. Users of online health information preferred a self-reliant approach and nonusers of online health information preferred a physician-reliant approach to involvement in medical decisions on the Reliance Scale. This study found significant differences between older adult users and nonusers of online and offline sources of health information and examined factors related to online health information engagement for medical decision making.     

Can non-fortified marine salt cover human needs for iodine?

Iodine deficiency remains a worldwide problem with two billion individuals having insufficient iodine intake. Universal salt iodisation was declared by UNICEF and WHO as a safe, cost-effective, and sustainable way to tackle iodine deficiency. In Portugal, the few studies available unravel an iodine status below the WHO guidelines for pregnant women and school-aged children. In the present study, the iodine levels of household salt consumed in Portugal was assessed, for the first time. Non-iodised (median 14?ppm) and fortified (median 48?ppm) marine salt samples showed iodine levels lower than the minimum and above the maximum threshold recommended by non-mandatory Portuguese law and WHO recommendations, respectively. This study calls attention to the fact that marine salt per se, in spite of containing a natural high amount of iodine, requires further fortification in order to be used as an effective tool to deal with iodine insufficiency.     

Low dietary iodine and thyroid anomalies in ring doves,Streptopelia risoria,Exposed to 3,4,3′,4′-Tetrachlorobiphenyl

Ring doves,Streptopelia risoria, were raised to adult size on either low iodine or normal iodine semi-purified diets. Insufficient iodine elicited thyroid hyperplasia comparable to that previously reported in Great Lakes herring gulls,Larus argentatus. This condition was reversed within seven days following a single dose (60 g/g body weight) of the PCB congener 3,4,3,4-tetrachlorobiphenyl (TCBP) in which group the thyroid weight plus colloid diameters were consistent with the development of large-colloid goiter. TCBP exposure also decreased the core body temperature, serum TT₄, and TT₃, indicating that low iodine euthyroidism changed to mild hypothyroidism. Acute exposure of the normal iodine doves did not cause hypothyroidism or affect thyroid histology, although serum TT₄ and TT₃ decreased significantly. In a second study, doves raised on the experimental diets received three TCBP doses (3×20 g/g body weight) over a 28-day period. The only significant effect associated with TCBP was decreased serum TT₄ which occurred in both dietary groups. The major conclusions are i) thyroid hyperplasia caused by low iodine was not enhanced by TCBP, ii) this effect is presumably due to opposing influences upon the thyroid-stimulating hormone (TSH) feedback system, and iii) this work in addition to previous studies indicate that PCB elicits large-colloid goiters in avian species generally, which is an inherently different response to hyperplastic goiter produced in mammals exposed to PCBs.     

Persistence of goiter despite oral iodine supplementation in goitrous children with iron deficiency anemia in Côte d'Ivoire

BACKGROUND: In developing countries, many children are at high risk of goiter and iron deficiency anemia. Because iron deficiency can have adverse effects on thyroid metabolism, iron deficiency may influence the response to supplemental iodine in areas of endemic goiter. OBJECTIVE: The aim of this study was to determine whether goitrous children with iron deficiency anemia would respond to oral iodine supplementation. DESIGN: A trial of oral iodine supplementation was carried out in an area of endemic goiter in western C?te d'Ivoire in goitrous children (n = 109) aged 6-12 y. Group 1 (n = 53) consisted of goitrous children who were not anemic. Group 2 (n = 56) consisted of goitrous children who had iron deficiency anemia. At baseline, thyroid gland volume and urinary iodine, thyrotropin, and thyroxine were measured by using ultrasound. Each child received 200 mg I orally and was observed for 30 wk, during which urinary iodine, thyrotropin, thyroxine, hemoglobin, and thyroid gland volume were measured. RESULTS: The prevalence of goiter at 30 wk was 12% in group 1 and 64% in group 2. The mean percentage change from baseline in thyroid volume 30 wk after administration of oral iodine was -45.1% in group 1 and -21.8% in group 2 (P < 0.001). Among the anemic children, there was a strong correlation between the percentage decrease in thyroid volume and hemoglobin concentration (r(2) = 0.65). CONCLUSION: The therapeutic response to oral iodine was impaired in goitrous children with iron deficiency anemia, suggesting that the presence of iron deficiency anemia in children limits the effectiveness of iodine intervention programs.     

Interactions of Fat and Carbohydrate Metabolism—New Aspects and Therapies: (Section of Therapeutics and Pharmacology)

NO one has so far produced anything approaching a clear picture of either fat or carbohydrate metabolism and the interactions of the two are still more involved and elusive although they clearly exist. Plants and animals build up reserves of fat from carbohydrate, but the reverse process (fat into carbohydrate), proved in plant seeds, is still unproven in animals, although theoretically possible.In normal human metabolism fat-carbohydrate interactions are almost hidden. The disturbances shown in the metabolism of a diabetic seem to give us the clearest indications of these interactions. Either carbohydrate or fat can be used as the main source of body fuel, but their metabolic course is very different, both as regards chemistry and function. It is only whep carbohydrate is not available, either in starvation or severe diabetes, that fat provides the fuel of the body; this contrast is also manifest in the blood and internal organs, especially the liver. Under the commonest normal conditions of diet carbohydrate is predominantly and preferentially used for metabolism. The liver is rich in glycogen, poor in fat; the blood fat is minimal and ketone bodies, although perhaps present in small amount in the blood at most times, are absent on common tests. As soon as carbohydrate is insufficiently available for the needs of metabolism, depot fat flows to the liver and is there catabolized to ketone bodies which recent proof has shown to be burned peripherally in the muscles independent of carbohydrate metabolism. This is a normal process, harmful only in diabetes, and especially harmful when it occurs suddenly, e.g. when insulin is cut off from a fat diabetic dog or human patient. A diabetic supports with ease a prolonged severe ketosis but suffers from one of sudden onset, although of milder severity. Insulin in the diabetic and sugar in the starved switches metabolism from fat to carbohydrate usage very quickly and ketonuria usually disappears in three to six hours.“Diabetic obesity” is very common and is often seen in the earliest stages and again after insulin treatment. It seems probable that hyperglycæmia causes this obesity and this has been clearly established by observations on an unusual case of lipæmia, diabetes and lipodystrophy.Lipæcmia may occur in two opposite phases of metabolism, one anabolic—when fat is on its way to storage, the other catabolic—when it is flowing from stores to the liver. The latter is the usual condition obvious in disease.Work has also been done which suggests that other lipotropic factors—choline, lipocaic, &c., exert an influence on carbohydrate-fat balance, more specifically the glycogen-fat balance in the liver.In America attention has been drawn to the frequent and persistenzt occurrence of fatty enlargement of the liver in diabetic children. The author has seen many diabetic children (usually in a state of chronic ketosis) with enlarged livers, but such enlargement has rapidly disappeared with better management of the diabetes. Only two out of some 500 diabetic children have clearly shown the unmistakable syndrome of “hepatomegalic dwarfism ”. In these two cases choline and lipocaic were given over prolonged periods without any effect: the liver, however, of one of these cases has since become normal by the addition of zinc protamine insulin.     

Inhibition of α-glucosidase and α-amylase by diaryl derivatives of imidazole-thione and 1,2,4-triazole-thiol

The in vivo and in vitro effects of 4,5-diphenylimidazole-2-thione (1), 4,5-diphenyl-1,2,4-triazole-3-thiol (2) and 5-(2-hydroxyphenyl)-4-phenyl-1,2,4-triazole-3-thiol (3) on α-glucosidase and α-amylase were investigated. The in vivo inhibition has been found to be dose-dependent and to occur at a value less than LD50. The in vitro treatment of the enzymes by 4,5-diphenylimidazole-2-thione exhibited a reversible inhibition of the non-competitive type with Ki value of 3.5 and 6.5×10(-5) M for α-glucosidase and α-amylase, respectively. 4,5-diphenyl-1,2,4-triazole-3-thione showed a reversible inhibition of the competitive and non-competitive types, with Ki value of 10(-5) M magnitude, for α-glucosidase and α-amylase. On the other hand, 5-(o-hydroxyphenyl)-4-phenyl-1,2,4-triazole-3-thione did not display an inhibitory effect towards α-amylase but showed a potent inhibition of the competitive type for hepatic α-glucosidase with 10(-5) M magnitude of Ki value.     

Development and relative validity of a food frequency questionnaire for the estimation of intake of retinol and β‐carotene

The aim of this study was to develop and validate a semiquantitative food frequency questionnaire to classify individuals according to their intakes of retinol and β‐carotene. Food items for the questionnaire were selected both on the basis of their contribution to total population intake of retinol and β‐carotene and on the proportion of between‐person variation explained, which was as calculated from data of two study populations in the Netherlands. Thus, 15 products containing retinol and 15 products containing β‐carotene were selected. These contributed over 90% to the total intake and explained 99% of the variation of retinol and β‐carotene, respectively. The questionnaire was validated against a dietary history in a population of 82 women (aged 30–49 years). The time elapsed between the two interviews was (on average) 25 days. Spearman rank‐order correlation coefficients comparing the questionnaire with the dietary history were 054, 0.59, and 0.64 for retinol, β‐carotene, and total vitamin A, respectively. The proportion of exact agreement in the two extreme categories of vitamin A intake, based on quintiles, was 56%. The corresponding gross misclassification (from 1 extreme category into the opposite) was 3%. These data indicate that a very short questionnaire can classify subjects into categories according to their vitamin A intake.     

Evaluation of Cuprimine® and Syprine® for decorporation of radioisotopes of cesium, cobalt, iridium and strontium

Cuprimine? and Syprine? are therapeutics approved by the USFDA to treat copper overload in Wilson Disease (a genetic defect in copper transport) by chelation and accelerated excretion of internally-deposited copper. These oral therapeutics are based on the respective active ingredients D-penicillamine (DPA) and N,N'-bis (2-aminoethyl) -1,2-ethanediamine dihydrochloride (Trien). Cuprimine is considered the primary treatment, although physicians are increasingly turning to Syprine as a first-line therapy. Both drugs exhibit oral systemic activity and low toxicity; their biological effects and safety are established. Previous in vivo studies using a rodent animal model established the decorporation potential of Cuprimine and Syprine for (60)Co and (210)Po. Currently these studies are being expanded to evaluate the in vivo decorporation efficacy of these drugs for several additional radionuclides. In this report, results of this investigation are discussed using the radionuclides (137)Cs, (60)Co, (192)Ir and (85)Sr. Short-term 48-h pilot studies were undertaken to evaluate DPA and Trien for their in vivo decorporation potential using male Wistar-Han rats. In these studies, a radionuclide solution was administered to the animals by intravenous (IV) injection, followed by a single IV dose of either DPA or Trien. Control animals received the radionuclide alone. Results show effective decorporation of (60)Co by DPA within the time frame evaluated. DPA and Trien were also modestly effective in decorporation of (137)Cs and (85)Sr, respectively. The study did not find DPA or Trien effective for decorporation of (192)Ir. Based on these encouraging findings, further studies to evaluate the dose-response profiles and timing of the chelator administration post exposure to radionuclides are warranted.