Iodine status remains critical in mother and infant in Central Anatolia (Kayseri) of Turkey

The use of breast milk iodine concentration in the first week of lactation as a biomarker of iodine status in breast-feeding women

Breast milk iodine concentration (BMIC) is a promising indicator of iodine status in lactating women. However, there are limited data on its usefulness to reflect maternal iodine deficiency. Therefore, the aim of our study was to assess iodine concentration in breast milk and urine samples in exclusively breast-feeding women. Eligible pregnant women undergoing routine antenatal care in a large hospital in Shaanxi Province, China, were followed up from the third trimester of pregnancy until the first week of lactation. Urine samples (20 ml) were collected during pregnancy and lactation. Iodine concentration in samples was measured based on Sandell-Kolthoff reaction. Breast milk samples (5 ml) were provided during lactation. A receiver operating curve (ROC) was constructed to determine the diagnostic performance of BMIC. An iodine-specific FFQ was completed twice during pregnancy and lactation. A total of 200 women completed the study. The overall median BMIC was 89 μg/l, indicating iodine sufficiency (i.e. BMIC reference range between 60 and 465 μg/l). Women reported similar median urinary iodine concentration (UIC) during pregnancy and lactation (112 and 113 μg/l, respectively), but their iodine status differed - mild-to-moderate iodine deficiency during pregnancy and iodine sufficiency during lactation. The ROC for BMIC using UIC as a reference standard was 0·755 (95 % CI: 0·644, 0·866). In conclusion, this study demonstrated that women were iodine sufficient in the first week of lactation as assessed by UIC, which was consistent with BMIC. These findings suggested that BMIC is a useful biomarker to assess iodine status in lactating women.

Assessment of the Iodine Status of Lactating Women and Infants in Shanghai, China

There is a risk of iodine deficiency among pregnant women in China. However, research on the iodine status of lactating women and infants is scarce. In this study, we aimed to evaluate the iodine status of lactating women and their infants and explore the relationship between breast milk iodine concentrations (BMICs) and urinary iodine concentrations (UICs). In total, 257 lactating women and their infants were recruited from the Shanghai Sixth People's Hospital East campus between May 2018 and May 2019. The BMIC and UIC were measured by inductively coupled plasma‒mass spectrometry (ICP‒MS). One-day 24-h dietary recall was used to determine the dietary intake of iodine. The mean dietary intake of iodine among the lactating women was 145.1 μg/day, and 97.83% (n = 225) of the lactating women had a dietary iodine intake below 240 μg/day. The median BMIC and UIC of the lactating women was 150.7 μg/L (interquartile range, IQR 102.9, 205.5) and 110.0 μg/L (IQR 65.8, 171.4), respectively, and the median UIC of the infants was 212.7 μg/L (IQR 142.1, 320.6). The BMIC of lactating women who consumed iodized salt was significantly higher than that of lactating women who did not consume iodized salt (p = 0.015). The infants' UIC values were significantly correlated with the BMIC values (r = 0.597**, p < 0.001). The iodine nutritional status of lactating women and infants in Shanghai was generally sufficient according to the WHO's iodine nutritional status recommendation. The use of iodized salt was related to increasing dietary iodine intake and the BMIC. Improvements in BMICs have positive effects on the nutritional levels of iodine in infants.

Breast Milk Iodine Concentration (BMIC) as a Biomarker of Iodine Status in Lactating Women and Children <2 Years of Age: A Systematic Review

Background: Iodine is needed for the production of thyroid hormones, which are essential for infant growth and development. Given that there are wide variations in breast milk iodine concentration (BMIC) and urinary iodine concentration (UIC), it is unclear if BMIC is associated with UIC in populations residing in iodine sufficient or deficient areas. Aim: To investigate if BMIC can be used as a biomarker for iodine status in lactating women and children <2 years of age. Methods: Electronic databases; PubMed, Web of Science and Scopus were searched until year 2021, for studies investigating the relationship between BMIC and UIC. Studies were reviewed for eligibility, according to inclusion and exclusion criteria, followed by data extraction, according to the PRISMA guidelines. Results: Overall, 51 studies met the criteria for inclusion in the systematic review. BMIC ranged from 18 to 1153 µg/L. In iodine-deficient and iodine-sufficient lactating women, BMIC ranged from 26 to 185 µg/L and 15 to 1006 µg/L, respectively. In most studies, the categorisation of iodine status assessed by median UIC was consistent with the categorisation of iodine status assessed by median BMIC cut off of ≥100 µg/L, to determine iodine sufficiency in lactating women and children <2 years of age. Conclusions: The systematic review indicated that BMIC is a promising biomarker of iodine status in lactating women and children <2 years of age. However, these data need to be interpreted cautiously, given the study limitations in the included studies. Future studies should consider investigating the optimal median BMIC, as there is a lack of high-quality observational and intervention studies in lactating women and infants.

Iodine status of Turkish pregnant women and their offspring: A national cross-sectional survey

BACKGROUND

This national cross-sectional survey aimed to assess the iodine status in pregnant women and their offspring, and also to demonstrate regional differences by measuring urinary iodine concentration (UIC). For each woman and her newborn a questionnaire was prepared with basic facts as age, parity number or birth weight and additional information regarding thyroid diseases, use of iodized salt in the household, extra iodine supplementation during pregnancy, education level and wage income.

METHODS

The target population represented 1444 pregnant women who gave birth between January 1 st, 2018 and 2019, and their offspring. Iodine deficiency for pregnant women and their offspring were defined as urine iodine level <150 μg/L and <100 μg/L, respectively. Results are given as median (25th-75th percentile).

RESULTS

The median UIC in the group of pregnant woman was 94 (52-153) μg/L. Within the sample of 1444 pregnant women, UIC indicative of mild iodine deficiency (100-149 μg/L) was present in 21 % (n = 306), moderate deficiency (50-99 μg/L) in 30 % (n = 430), and severe deficiency (<50 μg/L) in 23 % (n = 337). This study showed a prevalence of 74 % of iodine deficiency in Turkish pregnant woman. The median UIC in the group of offspring was 96 (41-191) μg/L. Within the new-borns, UIC indicative of mild iodine deficiency (50-99 μg/L) was present in 22 % (n = 323), moderate deficiency (20-49 μg/L) in 15 % (n = 222), and severe deficiency (<20 μg/L) in 13 % (n = 192). This survey showed a prevalence of 51 % of iodine deficiency in Turkish new-borns. Pregnant women with lower socioeconomic and education level, lower access to household iodized salt, lower rates of exposure to povidone-iodine containing skin disinfectant, higher parity and higher iodine deficiency had higher rates of iodine deficiency in their offspring. Regional differences were observed both in mothers and their offspring concerning their iodine status.

CONCLUSIONS

Our findings suggest that iodine deficiency is still an important public health problem in Turkey. More drastic measures should be taken to decrease these important iodine deficiencies, both in pregnant women and in their offspring.

Evaluation of the Bethesda System and the ACR TIRADS in an Endemic Goiter Region

BACKGROUND

Various factors can affect incidence of thyroid disorders and disease profiles may show abrupt changes in endemic goitrous areas. In this study, it was aimed to analyze the American College of Radiology (ACR) Thyroid Imaging Reporting and Data System (TI-RADS) and the Bethesda System for Reporting Thyroid Cytopathology (BSRTC) in terms of risk of malignancy and general recommendations in an endemic goiter region (EGR).

METHODS

In this retrospective study, a total of 500 patients who had thyroidectomy following thyroid fine needle aspiration biopsy were enrolled. For the assessment of thyroid cytology, BSRTC was used and for the evaluation of ultrasound features of thyroid nodules, ACR TIRADS lexicon was adopted. For the assessment of thyroid cytology, Bethesda classification was used and for the evaluation of ultrasound features of thyroid nodules, ACR TIRADS lexicon was adopted.

RESULTS

In the EGR setting, benign category of BSRTC had a cancer risk of 6.2% which was two times more than the 2017 BSRTC revision reported. Nodules 10-14.9 mm in diameter had nearly 4 times higher malignancy risk than nodules >15 mm. In this group of patients, the risk of malignancy for TIRADS level 1, 2, 3, 4 and 5 was 1.16%, 2.94%, 7%, 45.64% and 94.44%, respectively. The malignancy rates for Bethesda system category I, II, III, IV, V and VI were as follows: 14.43%, 6.2%, 19.05%, 36.73%, 75.68% and 100%.

CONCLUSIONS

There are slight differences between the common set of standards and this study results regarding risk of malignancy. This brings up the question whether there is need for revision for the use of categories and the appropriate management in endemic goiter regions.

Thyroglobulin Concentration and Maternal Iodine Status During Pregnancy: A Systematic Review and Meta-Analysis

Background: Literature to date has been inconclusive regarding the value of thyroglobulin (Tg) as a marker of iodine status in pregnant women. This systematic review and meta-analysis is one of the first to assess whether Tg concentration accurately reflects iodine status among pregnant women. Methods: We searched MEDLINE, the Web of Science, the Cochrane Library, Scopus, and other relevant databases to identify relevant studies published in the English language, between January 1988 and December 2018. The criteria for study inclusion in the systematic review were human studies, healthy pregnant women as participants, and available data for maternal urinary iodine concentration (UIC) and Tg level. Each study was assessed for quality and risk of bias. The pooled mean Tg values, and 95% confidence intervals were estimated in a population of women with UIC <150 and UIC ≥150 μg/L during pregnancy. Potential linear or nonlinear dose-response associations between maternal UIC and Tg concentration were examined. Results: Of 814 identified studies, 25 were eligible for inclusion in the meta-analysis. Studies included were conducted in Africa, Asia, Europe, South America, and the Oceania. The pooled mean (95% confidence interval [CI]) Tg concentration in iodine-deficient pregnant women was higher than that in iodine-sufficient pregnant women (10.73 μg/L [5.65-15.82] vs. 7.34 μg/L [2.20-12.47]); a comparison of the 95% CI showed that none of these values was significantly different. No significant differences were observed in Tg concentration between the two groups in each trimester of pregnancy. Dose-response meta-analyses revealed a significant nonlinear association between maternal UIC and Tg concentration during pregnancy. Among populations of pregnant women, an inverse association was found between UIC values <100 μg/L and Tg concentration (p-linearity = 0.007; p-nonlinearity = 0.027); however, higher values of UIC were not associated with Tg concentration. Conclusions: Our meta-analysis showed that Tg concentration can be a sensitive indicator of iodine deficiency, specifically in populations of pregnant women with median UIC <100 μg/L. Further studies are warranted to determine the sensitivity of Tg at different degrees of iodine deficiency during pregnancy.

Effects of mandatory salt iodization on breast milk, urinary iodine concentrations, and thyroid hormones: is iodine deficiency still a continuing problem?

PURPOSE

To investigate whether mandatory use of iodized salt in Turkey, since 1999 has sufficient effects on pregnant women and their newborns' urinary iodine concentrations (UIC), maternal and newborns' thyroid function tests and breast milk iodine concentrations (BMIC).

METHODS

This cross-sectional analytical-type study was conducted in an obstetrics and gynecology hospital in Konya, Turkey. One hundred and seven pregnant women and their 107 full-term newborns were included into the study. Levels of pregnant women and their newborns' UIC, thyroid-stimulated hormone (TSH), free triiodothyronine (fT3), free thyroxine (fT4), thyroglobulin (Tg), and BMIC were studied.

RESULTS

Of 107 women with term pregnancy, mean TSH value and hypothyroidism frequency were found as 2.34 ± 1.33 mIU/L and 18.7%, respectively. Cord blood TSH level was found higher (≥ 10 mIU/L) in five newborns. Accordingly, the incidence of transient congenital hypothyroidism was 4.7% (5/107). Tg levels were observed to be higher in 50.5% of newborns and 22.4% of pregnant women. Frequency of iodized salt use in pregnancies was detected as 96.3% in general population, 97.5% in urban, and 92.9% in rural areas. Of pregnancies and newborns, 57.9 and 53.3% were found to have deficient urinary iodine, respectively, and BMIC deficiency was detected as 52.0%. There was a significant positive correlation between pregnant women's UIC, and newborns' UIC and BMIC.

CONCLUSIONS

Despite the effective struggle with iodine deficiency and salt iodination control program in Konya, we concluded that iodine deficiency still persists as a significant problem in pregnancies.

Is there any difference between the iodine statuses of breast-fed and formula-fed infants and their mothers in an area with iodine sufficiency?

Despite substantial progress in the global elimination of iodine deficiency, lactating mothers and their infants remain susceptible to insufficient iodine intake. This cross-sectional study was conducted to compare iodine statuses of breast-fed and formula-fed infants and their mothers at four randomly selected health care centres in Tehran. Healthy infants <3 months old and their mothers were randomly selected for inclusion in this study. Iodine was measured in urine and breast milk samples from each infant and mother as well as commercially available infant formula. The study included 124 postpartum mothers (29·2 (sd 4·9) years old) and their infants (2·0 (sd 0·23) months old). The iodine concentrations were 50–184 µg/l for infant formula, compared with a median breast milk iodine concentration (BMIC) of 100 µg/l in the exclusive breast-feeding group and 122 µg/l in the partial formula feeding group. The median values for urinary iodine concentration in the exclusive breast-feeding group were 183 µg/l (interquartile range (IQR) 76–285) for infants and 78 µg/l (IQR 42–145) for mothers, compared with 140 µg/l (IQR 68–290) for infants and 87 µg/l (IQR 44–159) for mothers in the formula feeding group. These differences were not statistically significant. After adjustment for BMIC, ANCOVA revealed that feeding type (exclusive breast-feeding v. partial formula feeding) did not significantly affect the infants’ or mother’s urinary iodine levels. Thus, in an area with iodine sufficiency, there was no difference in the iodine statuses of infants and mothers according to their feeding type.

Breast-Milk Iodine Concentrations and Iodine Levels of Infants According to the Iodine Status of the Country of Residence: A Systematic Review and Meta-Analysis

BACKGROUND

Iodine, an essential micronutrient, plays a critical role in normal growth and development, especially during the first two years of life. This systematic review and meta-analysis is among the first to evaluate breast-milk iodine concentrations and infant iodine status in countries characterized by iodine sufficiency or deficiency.

METHODS

PubMed, Web of Science, Cochrane Library, Google Scholar, and other relevant databases, as well as reference lists of previous reviews, were searched for relevant studies published between 1986 and 2016. Mean or median breast-milk and infant urinary iodine concentrations, along with other relevant data, were extracted from eligible studies. Each study was assessed for quality and risk of bias.

RESULTS

Of the 496 identified studies, 57 met the criteria for inclusion in the meta-analysis. The mean (confidence interval [CI]) iodine concentrations in maternal colostrum were 152.0 μg/L [CI 106.2-198.7 μg/L] and 57.8 μg/L [CI 41.4-74.1 μg/L] in iodine-sufficient and -deficient countries, respectively, indicating a significant difference between the two iodine statuses. By contrast, the corresponding values in mature milk did not differ significantly between mothers in iodine-sufficient and -deficient countries (71.5 μg/L [CI 51.0-92.0 μg/L] and 28.0 μg/L [CI -13.8 to 69.9 μg/L], respectively]. The weighted urinary iodine levels [CIs] of breast-fed infants in iodine-sufficient countries were significantly higher than those in iodine-deficient countries (164.5 μg/L [CI 116.4-212.7 μg/L] vs. 70.4 μg/L [CI 46.2-94.6 μg/L]). Similarly, a significant difference was observed in the pooled estimates of urinary iodine levels [CIs] among formula-fed infants in iodine-sufficient versus iodine-deficient countries (310.3 μg/L [CI 287.4-342.1 μg/L] vs. 38.3 μg/L [CI 23.4-53.2 μg/L]).

CONCLUSION

The meta-analysis reveals that in iodine-sufficient countries, the mean iodine concentrations in colostrum and mature breast milk corresponded to iodine sufficiency among infants. The results are thus compatible with the international recommendation that lactating women and infants younger than two years of age who reside in iodine-sufficient countries do not require iodine supplementation.

Ultrasound Measurements of Thyroid Gland Volume at 36 Weeks' Corrected Gestational Age in Extremely Preterm Infants Born before 28 Weeks' Gestation

BACKGROUND

Thyroid ultrasound is a non-invasive imaging tool and provides good evaluation of thyroid anatomy, location, vascularisation, and echogenicity. The aim of this study was to assess thyroid function and thyroid volume in extremely preterm infants born before 28 weeks' gestation evaluated at 36 weeks' corrected gestational age (CGA) compared to term infants' normative data in the literature.

DESIGN

In this largest prospective UK study of extremely premature infants born at less than 28 weeks' gestation, thyroid volume measurement was assessed at 36 weeks' CGA. Fifty-five extremely preterm infants (28 males) who were born before 28 weeks' gestation were recruited to the study. All infants had ultrasound assessment of the thyroid gland at 36 weeks' CGA. We also prospectively measured thyroid stimulating hormone (TSH) and free thyroxine (FT4) in all infants at the time of recruitment (within 5 days of birth), at days 14, 21, and 28, and at 36 weeks' CGA.

RESULTS

The mean thyroid volume was measured at 0.57 mL (SD ±0.18). There was no association between mean thyroid volume and thyroid function (TSH or FT4). No associations were found between mean thyroid volume and gestation or birth weight in these infants.

CONCLUSIONS

Our findings provide a reference range with a mean thyroid volume of 0.57 mL (SD ±0.18) in this extremely preterm age group if less than 28 weeks' gestation. Thyroid volume at birth can vary from country to country due to variations in iodine intake as well as gestational age.

Breast Milk Iodine Concentration Is a More Accurate Biomarker of Iodine Status Than Urinary Iodine Concentration in Exclusively Breastfeeding Women

Background: Iodine status in populations is usually assessed by the median urinary iodine concentration (UIC). However, iodine is also excreted in breast milk during lactation; thus, breast milk iodine concentration (BMIC) may be a promising biomarker of iodine nutrition in lactating women. Whether the mammary gland can vary fractional uptake of circulating iodine in response to changes in dietary intake is unclear.Objective: We evaluated UIC and BMIC as biomarkers for iodine status in lactating women with a wide range of iodine intakes.Methods: We recruited 866 pairs of lactating mothers and exclusively breastfed infants from 3 iodine-sufficient study sites: Linfen, China (n = 386); Tuguegarao, Philippines (n = 371); and Zagreb, Croatia (n = 109). We also recruited iodine-deficient lactating women from Amizmiz, Morocco (n = 117). We collected urine and breast milk samples and measured UIC and BMIC.Results: In the 3 iodine-sufficient sites, a pooled regression analysis of the estimated iodine excretion revealed higher fractional iodine excretion in breast milk than in urine at borderline low iodine intakes. In contrast, in the iodine-deficient site in Morocco, a constant proportion (∼33%) of total iodine was excreted into breast milk.Conclusions: In iodine-sufficient populations, when iodine intake in lactating women is low, there is increased partitioning of iodine into breast milk. For this reason, maternal UIC alone may not reflect iodine status, and BMIC should also be measured to assess iodine status in lactating women. Our data suggest a BMIC reference range (2.5th and 97.5th percentiles) of 60-465 μg/kg in exclusively breastfeeding women. This trial was registered at clinicaltrials.gov as NCT02196337.

Iodine supplementation for women during the preconception, pregnancy and postpartum period

BACKGROUND

Iodine is an essential nutrient required for the biosynthesis of thyroid hormones, which are responsible for regulating growth, development and metabolism. Iodine requirements increase substantially during pregnancy and breastfeeding. If requirements are not met during these periods, the production of thyroid hormones may decrease and be inadequate for maternal, fetal and infant needs. The provision of iodine supplements may help meet the increased iodine needs during pregnancy and the postpartum period and prevent or correct iodine deficiency and its consequences.

OBJECTIVES

To assess the benefits and harms of supplementation with iodine, alone or in combination with other vitamins and minerals, for women in the preconceptional, pregnancy or postpartum period on their and their children's outcomes.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register (14 November 2016), and the WHO International Clinical Trials Registry Platform (ICTRP) (17 November 2016), contacted experts in the field and searched the reference lists of retrieved studies and other relevant papers.

SELECTION CRITERIA

Randomized and quasi-randomized controlled trials with randomisation at either the individual or cluster level comparing injected or oral iodine supplementation (such as tablets, capsules, drops) during preconception, pregnancy or the postpartum period irrespective of iodine compound, dose, frequency or duration.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial eligibility, risk of bias, extracted data and conducted checks for accuracy. We used the GRADE approach to assess the quality of the evidence for primary outcomes.We anticipated high heterogeneity among trials, and we pooled trial results using random-effects models and were cautious in our interpretation of the pooled results.

MAIN RESULTS

We included 14 studies and excluded 48 studies. We identified five ongoing or unpublished studies and two studies are awaiting classification. Eleven trials involving over 2700 women contributed data for the comparisons in this review (in three trials, the primary or secondary outcomes were not reported). Maternal primary outcomesIodine supplementation decreased the likelihood of the adverse effect of postpartum hyperthyroidism by 68% (average risk ratio (RR) 0.32; 95% confidence interval (CI) 0.11 to 0.91, three trials in mild to moderate iodine deficiency settings, 543 women, no statistical heterogeneity, low-quality evidence) and increased the likelihood of the adverse effect of digestive intolerance in pregnancy by 15 times (average RR 15.33; 95% CI 2.07 to 113.70, one trial in a mild-deficiency setting, 76 women, very low-quality evidence).There were no clear differences between groups for hypothyroidism in pregnancy or postpartum (pregnancy: average RR 1.90; 95% CI 0.57 to 6.38, one trial, 365 women, low-quality evidence, and postpartum: average RR 0.44; 95% CI 0.06 to 3.42, three trials, 540 women, no statistical heterogeneity, low-quality evidence), preterm birth (average RR 0.71; 95% CI 0.30 to 1.66, two trials, 376 women, statistical heterogeneity, low-quality evidence) or the maternal adverse effects of elevated thyroid peroxidase antibodies (TPO-ab) in pregnancy or postpartum (average RR 0.95; 95% CI 0.44 to 2.07, one trial, 359 women, low-quality evidence, average RR 1.01; 95% CI 0.78 to 1.30, three trials, 397 women, no statistical heterogeneity, low-quality evidence), or hyperthyroidism in pregnancy (average RR 1.90; 95% CI 0.57 to 6.38, one trial, 365 women, low-quality evidence). All of the trials contributing data to these outcomes took place in settings with mild to moderate iodine deficiency. Infant/child primary outcomesCompared with those who did not receive iodine, those who received iodine supplements had a 34% lower likelihood of perinatal mortality, however this difference was not statistically significant (average RR 0.66; 95% CI 0.42 to 1.03, two trials, 457 assessments, low-quality evidence). All of the perinatal deaths occurred in one trial conducted in a severely iodine-deficient setting. There were no clear differences between groups for low birthweight (average RR 0.56; 95% CI 0.26 to 1.23, two trials, 377 infants, no statistical heterogeneity, low-quality evidence), neonatal hypothyroidism/elevated thyroid-stimulating hormone (TSH) (average RR 0.58; 95% CI 0.11 to 3.12, two trials, 260 infants, very low-quality evidence) or the adverse effect of elevated neonatal thyroid peroxidase antibodies (TPO-ab) (average RR 0.61; 95% CI 0.07 to 5.70, one trial, 108 infants, very low-quality evidence). All of the trials contributing data to these outcomes took place in areas with mild to moderate iodine deficiency. No trials reported on hypothyroidism/elevated TSH or any adverse effect beyond the neonatal period.

AUTHORS' CONCLUSIONS

There were insufficient data to reach any meaningful conclusions on the benefits and harms of routine iodine supplementation in women before, during or after pregnancy. The available evidence suggested that iodine supplementation decreases the likelihood of postpartum hyperthyroidism and increases the likelihood of the adverse effect of digestive intolerance in pregnancy - both considered potential adverse effects. We considered evidence for these outcomes low or very low quality, however, because of study design limitations and wide confidence intervals. In addition, due to the small number of trials and included women in our meta-analyses, these findings must be interpreted with caution. There were no clear effects on other important maternal or child outcomes though these findings must also be interpreted cautiously due to limited data and low-quality trials. Additionally, almost all of the evidence came from settings with mild or moderate iodine deficiency and therefore may not be applicable to settings with severe deficiency.More high-quality randomised controlled trials are needed on iodine supplementation before, during and after pregnancy on maternal and infant/child outcomes. However, it may be unethical to compare iodine to placebo or no treatment in severe deficiency settings. Trials may also be unfeasible in settings where pregnant and lactating women commonly take prenatal supplements with iodine. Information is needed on optimal timing of initiation as well as supplementation regimen and dose. Future trials should consider the outcomes in this review and follow children beyond the neonatal period. Future trials should employ adequate sample sizes, assess potential adverse effects (including the nature and extent of digestive intolerance), and be reported in a way that allows assessment of risk of bias, full data extraction and analysis by the subgroups specified in this review.

EVALUATION OF URINARY IODINE LEVELS AND THYROID FUNCTION TESTS IN PREGNANT WOMEN AND THEIR INFANTS

Introduction

In this study we aimed to evaluate urinary iodine excretion and the serum levels of thyroid-stimulating hormone (TSH), free triiodothyronine (fT3), free thyroxine (fT4) and thyroglobulin (Tg) in pregnants and their newborn infants.

Materials and Methods

This study was performed in Konya Faruk Sukan Children and Maternity Hospital, Konya Beyhekim State Hospital and Hospital of Selcuk University Medical Faculty. 180 pregnant women and their healthy infants born at 37-40 gestational weeks.Term infants included in this study were aged between 1-7 days, healthy. Midurination urine samples were taken into deiodinized plastic bottles and 2 mL of these samples were aliquoted to deiodinized eppendorf tubes.

Results

Median urinary iodine concentration (UIC) was 95.5 µg/L for pregnant women and 245 µg/L for their infants. Frequency of iodine deficiency was observed as 63.3% (n=114) (<150 µg/L) and 24.4% (n=44) (<100 µg/L) in mothers and their infants, respectively. UIC of the infants whose mothers used iodized salt was significantly higher than the one whose mothers used rocksalt (p=0.030).

Conclusions

It was stated in our study that UIC of pregnants was lower than the target limit (<150 µg/L), suggested by World Health Organisation (WHO) and iodine deficiency in pregnants is still a problem in our city located in the centre of Turkey. Iodine deficiency was observed in 24.4% of the infants and this prevalence suggests us that iodine deficiency is still an important health problem in infants.

Neonatal thyrotropin concentration and iodine nutrition status of mothers: a systematic review and meta-analysis

BACKGROUND

Low maternal iodine intake disturbs the thyroid function of neonates transiently or permanently.

OBJECTIVE

To our knowledge, we conducted one of the first systematic reviews and meta-analyses aimed at exploring the association of neonatal thyrotropin concentrations and iodine status of mothers during pregnancy and early postpartum periods.

DESIGN

Data were collected through literature searches for studies published between 1969 and 2015 with the use of electronic databases. Mean or median maternal urinary iodine and neonatal thyrotropin concentrations, along with other relevant data, were extracted from eligible studies. The quality and risk of bias of each study was assessed.

RESULTS

A random-effects model was used for the analysis. Of 110 studies identified, 25 trials were shown to be eligible for inclusion in the meta-analysis. Mean (95% CI) thyrotropin concentrations of neonates born to mothers with iodine deficiency were higher than in neonates born to mothers with iodine sufficiency during pregnancy in both heel blood samples [1.79 mIU/L (95% CI: 1.61, 1.97 mIU/L) compared with 1.75 mIU/L (95% CI: 1.68, 1.82 mIU/L), respectively] and cord blood samples [11.91 mIU/L (95% CI: 6.67, 17.14 mIU/L) compared with 6.15 mIU/L (95% CI: 4.30, 8.01 mIU/L), respectively]. There were no significant differences in neonatal thyrotropin concentrations of heel samples between mothers with iodine deficiency and those with sufficiency during the early postpartum period; however, the values of thyrotropin in cord samples of neonates born to mothers with iodine deficiency were significantly higher than in neonates born to mothers with iodine sufficiency [11.62 mIU/L (95% CI: 10.47, 12.77 mIU/L) compared with 7.40 mIU/L (95% CI: 6.21, 8.59 mIU/L)].

CONCLUSION

Our findings reveal that, compared with heel blood samples, neonatal thyrotropin in samples collected from the cord are more sensitive to the iodine status of mothers; however, further investigations are required in this regard.

Transient Congenital Hypothyroidism in Turkey: An Analysis on Frequency and Natural Course

OBJECTIVE

Prevalence of congenital hypothyroidism (CH) in Turkey at birth was reported to be as high as 1:650 in 2008-2010. Incidence rates of permanent and transient CH separately are unknown due to lack of follow-up data. We aimed to evaluate the impact of transient hypothyroidism on increasing incidence of CH and to determine the natural course and the clinical, biochemical, and imaging characteristics of transient CH.

METHODS

Baseline and follow-up data of the infants with CH detected at screening in six provinces in the Black Sea Region were analyzed retrospectively during a time period covering the years 2008-2010.

RESULTS

Among 138 cases (48% female), 16 (12%) showed transient hyperthyrotropinemia which resolved without intervention. Of the treated 122 cases, 63 (52%) had transient CH. While its frequency was 35% in 2008, it increased to 56% in 2009-2010, following a lowering of the thyroid stimulating hormone cutoff value. The frequency was higher in inland provinces than in coast (67% vs. 43%; p=0.01).Clinical characteristics of permanent and transient cases were similar except female-to-male sex ratios (1.5:1 vs. 0.6:1; p=0.02). L-thyroxine was discontinued in 70% of transient cases before 3 years of age at a median age of 19 (2-36) months. The only indication for early discontinuation of treatment was a low L-thyroxine dose, which was 1.25±0.27 µg/kg/day at withdrawal time.

CONCLUSION

Our regional follow-up data showed that more than half of newborns with primary CH had transient thyroid dysfunction. In the majority of cases, discrimination between transient and permanent CH can be made before age 3 years, as indicated by cessation of L-thyroxine treatment.

Iodine nutrition status in lactating mothers residing in countries with mandatory and voluntary iodine fortification programs: an updated systematic review

BACKGROUND

The aim of this review is to assess data available on iodine nutrition status in lactating mothers residing in countries with mandatory and voluntary iodine fortification programs and/or iodine supplementation.

SUMMARY

A systematic review was conducted by searching articles published between 1964 and 2013 in Pub Med, ISI Web, and Cochrane Library using iodine nutrition, lactation, iodine supplementation, and iodine fortification as keywords for titles and/or abstracts. Relevant articles were included if they reported urinary iodine concentration (UIC) in lactating mothers and, if determined, the type of iodine fortification program and/or iodine supplementation. Forty-two studies met the inclusion criteria. Among these, 21 studies assessed lactating mothers in countries with a mandatory iodine fortification program, 17 studies were from countries with voluntary and/or without iodine fortification programs, and four studies assessed iodine nutrition status in lactating mothers undergoing iodine supplementation. Among countries with mandatory iodine fortification programs, the range of salt iodization level in lactating mothers with a UIC <100 μg/L was between 8 and 40 ppm, whereas among lactating mothers with UIC >100 μg/L, it was between 15 and 60 ppm. Levels of UIC <100 μg/L were observed among lactating women in India, Denmark, Mali, New Zealand, Australia, Slovakia, Sudan, and Turkey, whereas in countries such as Chile, Iran, Mongolia, New Guinea, and Nigeria, the median or mean of UIC was >100 μg/L. There was a median or mean UIC <100 μg/L in nearly all lactating mothers residing in countries where implementation of universal salt iodization program was voluntary, including Switzerland, Australia, New Zealand, Ireland, and Germany. However, in some countries with voluntary iodine fortification programs, such as the United States, Spain, and Japan, a mean or median UIC of >100 μg/L has been reported.

CONCLUSIONS

Although universal salt iodization is still the most feasible and cost-effective approach for iodine deficiency control in pregnant and lactating mothers, UIC in lactating mothers of most countries with voluntary programs and in areas with mandatory iodine fortification is still within the iodine deficiency range, indicating that iodine supplementation in daily prenatal vitamin/mineral supplements in lactating mothers is warranted. However, further investigations are still recommended in this regard.

The comparison of thyroxine versus thyroxine plus oral iodine in the treatment of congenital hypothyroidism due to iodine deficiency

AIM

Iodine deficiency is one of the most important causes of congenital hypothyroidism. In addition to thyroid hormone replacement, iodine supplementation is also given to newborns with congenital hypothyroidism due to iodine deficiency. We aimed to determine whether it is beneficial to administer iodine supplementation in addition to the L-thyroxine (L-T4) treatment of newborns with congenital hypothyroidism due to iodine deficiency.

MATERIALS AND METHODS

Of 51 newborns, 26 who were diagnosed with congenital hypothyroidism due to iodine deficiency were treated with L-T4. The remaining 25 cases were given L-T4 plus 100 μg/day of oral iodine. Free triiodothyronine (fT3), free thyroxine (fT4), thyroid-stimulating hormone (TSH), thyroglobulin (TG), thyroid volume, urine iodine and breast milk iodine levels were measured in the first and third months of treatment, and the data were compared between the two groups.

RESULTS

First- and third-month values of fT3, fT4, TSH, TG and thyroid volume for both groups were statistically similar. There was no significant difference between the two groups in respect to falling levels of fT3 and TSH, the rate of increase of fT4 levels or the shrinkage rate of thyroid volume.

CONCLUSION

In this study, the addition of oral iodine to L-T4 treatment provided no benefit compared to treatment with L-T4 alone.

Nomogram-based evaluation of thyroid function in appropriate-for-gestational-age neonates in intensive care unit

OBJECTIVE

The objective of this study was to help neonatologists to interpret the thyroid hormone results accurately, and also to provide reference ranges and/or nomograms of FT4 (free thyroxine) and thyrotropin against gestational age at postnatal 1 week and 1 month in order to assess thyroid function in AGA (appropriate for gestational age) neonates in intensive care unit.

STUDY DESIGN

This is a retrospective study. We included a total number of 515 AGA neonates between 24 and 42 weeks of gestation. Routine results of serum FT4 and TSH that had been analyzed with an immunoassay were collected from existing laboratory data. Least square regression analyses were used to estimate both the mean and the s.d. curves as polynomial functions of gestational age.

RESULT

Free T4 levels were correlated with gestational age both at postnatal 1 week (r=0.39, P<0.001) and 1 month (r=0.26, P<0.001). Serum TSH levels at postnatal 1 week and 1 month did not show any correlation with gestational age. Scatterplots of FT4 levels against gestational age at 1 week and 1 month, showing the predicted 2.5th, 50th and 97.5th percentiles and central 95% reference ranges for TSH were provided.

CONCLUSION

Gestational age-specific nomograms for FT4 and reference ranges for TSH at postnatal 1 week and 1 month in AGA neonates have been developed. This can help neonatologists to interpret the thyroid hormone results accurately. Further studies providing reference ranges/nomograms for thyroid function in small-for-gestational-age neonates are needed.

Validation of an optimized method for the determination of iodine in human breast milk by inductively coupled plasma mass spectrometry (ICPMS) after tetramethylammonium hydroxide extraction

In this study a novel method to determine iodine concentrations in human breast milk was developed and validated. The iodine was analyzed by inductively coupled plasma mass spectrometry (ICPMS) following tetramethylammonium hydroxide (TMAH) extraction at 90°C in disposable polypropylene tubes. While similar approaches have been used previously, this method adopted a shorter extraction time (1h vs. 3h) and used antimony (Sb) as the internal standard, which exhibited greater stability in breast milk and milk powder matrices compared to tellurium (Te). Method validation included: defining iodine linearity up to 200μgL(-1); confirming recovery of iodine from NIST 1549 milk powder. A recovery of 94-98% was also achieved for the NIST 1549 milk powder and human breast milk samples spiked with sodium iodide and thyroxine (T4) solutions. The method quantitation limit (MQL) for human breast milk was 1.6μgL(-1). The intra-assay and inter-assay coefficient of variation for the breast milk samples and NIST powder were <1% and <3.5%, respectively. NIST 1549 milk powder, human breast milk samples and calibration standards spiked with the internal standard were all stable for at least 2.5 months after extraction. The results of the validation process confirmed that this newly developed method provides greater accuracy and precision in the assessment of iodine concentrations in human breast milk than previous methods and therefore offers a more reliable approach for assessing iodine concentrations in human breast milk.

Systematic review using meta-analyses to estimate dose-response relationships between iodine intake and biomarkers of iodine status in different population groups

The objective of this systematic review was to identify studies investigating iodine intake and biomarkers of iodine status, to assess the data of the selected studies, and to estimate dose-response relationships using meta-analysis. All randomized controlled trials, prospective cohort studies, nested case-control studies, and cross-sectional studies that supplied or measured dietary iodine and measured iodine biomarkers were included. The overall pooled regression coefficient (β) and the standard error of β were calculated by random-effects meta-analysis on a double-log scale, using the calculated intake-status regression coefficient (β) for each individual study. The results of pooled randomized controlled trials indicated that the doubling of dietary iodine intake increased urinary iodine concentrations by 14% in children and adolescents, by 57% in adults and the elderly, and by 81% in pregnant women. The dose-response relationship between iodine intake and biomarkers of iodine status indicated a 12% decrease in thyroid-stimulating hormone and a 31% decrease in thyroglobulin in pregnant women. The model of dose-response quantification used to describe the relationship between iodine intake and biomarkers of iodine status may be useful for providing complementary evidence to support recommendations for iodine intake in different population groups.

Maternal and neonatal urinary iodine status and its effect on neonatal TSH levels in a mildly iodine-deficient area

OBJECTIVE

Iodine deficiency and excess are the most important factors that affect screening and recall rates of congenital hypothyroidism. The purpose of this study was to investigate the urinary iodine status in newborns and their mothers and its effects on neonatal thyroid-stimulating hormone (TSH) levels in a mildly iodine-deficient area.

METHODS

A total of 116 newborns and their mothers were included in the study. Urinary iodine levels were measured from healthy mothers and their babies on the 5th day following birth. Neonatal TSH levels were screened, and TSH and free thyroxine (fT4) levels were measured on the 15th day in the recall cases. T4 treatment was started in infants with high TSH and low fT4 levels. These measurements were repeated on the 30th day in these newborns.

RESULTS

Ninety-nine percent of the mothers included in the study were using iodized salt. The median urinary iodine level in the newborns was 279 µg/L, while it was 84 µg/L in their mothers. The rate of iodine deficiency among the mothers was 56.8%, and the rate of iodine excess was 8.6%. This rate was 10.3% for iodine deficiency and 61.2% for iodine excess in the newborns. The recall rate at the screening was 9.5% (n=11). The urinary iodine levels were above 200 µg/L in three newborns who had transient hyperthyrotropinemia.

CONCLUSIONS

Iodine deficiency was more frequently observed in nursing mothers, and iodine excess was more frequently seen in their newborns. The iodine excess noted in the newborns was attributed to the use of antiseptics containing iodine. The iodine excess leads to increases in recall rates, screening costs, and frequency of transient hyperthyrotropinemia.

Thyroid functions of neonates with Down syndrome

Background

We aimed to evaluate thyroid functions and volumes and detect abnormalities in 80 neonates with Down syndrome.

Methods

Data about free triiodothyronine, free thyroxine, thyroid stimulating hormone, thyroglobulin and urinary iodine levels, and ultrasonographic thyroid volume were collected.

Results

Abnormal thyroid function tests were detected in 53.8% of the patients (n = 50) and these were hyperthyrotropinemia, hypothyroidism, iodine deficiency and iodine overload in 32, 2, 12 and 4 patients, respectively. Thyroid volumes were assessed in 36 patients and a total of 17 abnormalities were detected (7 hypoplasia, 3 agenesis and 7 goiter). In patients with hyperthyrotropinemia mean thyroid volume was significantly greater and mean TSH was significantly higher when compared to the patients without hyperthyrotropinemia.

Conclusion

Neonatal screening by thyroid function tests in Down syndrome should be performed to prevent further intellectual deterioration and improve overall development. In the neonatal period, the risk of hyperthyrotropinemia should be kept in mind.

A review on the metabolic disorders of iodine deficiency

Iodine is in the crucial parts of two hormones of T4 and T3 produced by the thyroid glands which are essential for all the aspects of human metabolisms. It is demonstrated that iodine deficiency can be considered as sole cause of many thyroid abnormalities including mental disorders. Iodine deficiency of sufficient degree to cause hypothyroidism during fetus life and early infancy will be accompanied with brain abnormality possibly to the stage of mental retardation. The iodine deficiency among subjects in their early stage of childhood is not as severe as those in their fetus or infancy. In adult subjects the sever iodine deficiency can be also associated with mental disorders due to the direct side effects of hypothyroidism occurred by lack of iodine. The clinical manifestation of iodine deficiency show itself with psychological disorders in adult subjects. The status of iodine within blood can be evaluated through measurement of urinary iodine level and the low urinary concentration is an indicative of hypothyroidism. Mental retardation and brain damage due to iodine deficiency can be prevented if iodine supplementation prescribed duly on time.

Cord blood thyroid-stimulating hormone and free T4 levels in Turkish neonates: is iodine deficiency still a continuing problem?

BACKGROUND

The objectives of this study were to determine the cord blood thyroid-stimulating hormone (TSH) and free T(4) (FT(4) ) levels in Turkish neonates and to determine whether these variables reveal iodine deficiency.

METHODS

We collected 818 cords from healthy mothers at parturition and measured levels of FT(4) and TSH. We also measured cord blood FT(4) and TSH levels in different stages of gestation and gender. We grouped the neonates according to cord serum TSH levels, either being less (Group A) or greater (Group B) than 10 mIU/L. Group A included 589 neonates (300 girls [51%] and 289 boys [49%]) and Group B included 229 neonates (105 girls [45%] and 124 boys [55%]).

RESULTS

The percentage of subjects with cord blood TSH < 10 mIU/L and >10 mIU/L was 72% and 28%, respectively. Although cord TSH levels in Group B were greater than those in Group A (P < 0.001), cord blood FT(4) levels in Group B were lower than those in Group A (P < 0.05). There was no difference between both sex in terms of birthweight and maternal age. TSH and FT(4) levels did not vary according to neonate sex during gestation, except for from week 37 to 41. TSH levels of male neonates at the 41st week of gestation were higher than those of female neonates (P < 0.05). There were no effects of birthweight on TSH and FT(4) levels if the neonate was lighter than 2500 g at birth. TSH levels of male neonates were higher than those of female neonates when their birthweights were <2500 g (P < 0.05). There was no significant difference in TSH levels according to birthweights in male neonates.

CONCLUSION

Our data provide the normative data for cord blood TSH and FT(4) levels in Turkish neonates and show that iodine deficiency is a still a public health problem in Turkey. These measurements can be useful for detection and verification of hypothyroidism in a screening program for congenital hypothyroidism as well as evaluation of the success of the iodination program.

Iodine intake is still inadequate among pregnant women eight years after mandatory iodination of salt in Turkey

BACKGROUND

A recent study showed first sign of reduction in goiter prevalence and elimination of iodine deficiency state among school-age children in Turkey after a decade of mandatory iodination of table salt. However, iodine status among pregnant women is a still debated issue in our country.

AIM

To investigate iodine status, iodized salt consumption rate, and goiter prevalence in 1st trimester pregnant women 8 yr after the mandatory iodination. MATERIAL/ SUBJECTS AND METHODS: One hundred and forty-one 1sttrimester pregnant women who had been followed-up between January and October 2006 in the obstetric outpatient clinics in Turkey were included. Besides a physical examination, subjects underwent laboratory investigations for free T(3), free T(4), and urinary iodine concentration (UIC). All subjects completed a questionnaire regarding sociodemographic parameters, use of iodized salt, and pregnancy history. Goiter status was revealed by a palpation method according to World Health Organization (WHO) guidelines.

RESULTS

In this study, we found that the median UIC of pregnant women was 149.7 microg/l (range 20.9-275.1 microg/l). Almost half of the subjects were below the WHO, United Nations Children's Fund, and International Council for the Control of Iodine Deficiency Disorders lower median reference limits of 150 microg/l. Total goiter prevalence was 24.8%, of which 9.2% were visible goiters. Among the study patients, 2.1% had subclinical hypothyroidism, and 0.7% had overt hypothyroidism. The rate for iodized salt use among the pregnant women was 95%.

CONCLUSION

Our study revealed that iodine deficiency still remains a serious problem for pregnant women. Based on our results, antenatal follow-up protocols in the primary care setting in Turkey must include iodine supplementation.

Neonatal TSH screening: is it a sensitive and reliable tool for monitoring iodine status in populations?

Iodine deficiency is the most common cause of preventable brain damage in the newborn. The indicators for assessing iodine nutritional status include urinary iodine excretion, thyroid size, thyroid stimulating hormone (TSH) and thyroglobulin (Tg) concentrations in the blood. Neonatal TSH concentration is increased when the supply of thyroid hormone and iodine from the maternal circulation to the foetus has been compromised. The World Health Organization (WHO) has suggested that when a sensitive assay is used on samples collected 3-4 days after birth, a <3% frequency of TSH concentrations >5 mIUl(-1) indicates iodine sufficiency in a population. However, many studies have attempted to apply the frequency of neonatal TSH values >5 mIUl(-1) in determining population iodine status and monitoring intervention programmes, and although some have proven to be successful, most have provided conflicting or uncertain data. This is due to the many technical issues that remain unresolved on the use of neonatal TSH screening for monitoring iodine status, making it doubtful as a sensitive and reliable quantitative tool. More research is required to resolve these issues. In the interim, WHO should consider withdrawing its current guidelines for neonatal TSH screening for monitoring iodine deficiency in populations.

Iodine overload and severe hypothyroidism in two neonates

Iodine overload frequently leads to transient hyperthyrotropinemia or hypothyroidism, and rarely to hyperthyroidism in neonates. Iodine exposure can be prenatal, perinatal or postnatal. Herein we report two newborn infants who developed severe hypothyroidism due to iodine overload. The overloading was caused by excessive use of an iodinated antiseptic for umbilical care in the first case, and as a result of maternal exposure and through breast milk with a high iodine level in the second case. Presenting the two cases, we wanted to draw attention to these preventable causes of hypothyroidism in infants.

Neonatal sludge: a finding of congenital hypothyroidism

Congenital hypothyroidism is one of the most urgent diseases of the neonate. When diagnosed and treated at an early stage, its most important complication, mental retardation, is preventable. The signs of congenital hypothyroidism are nonspecific in neonates. Only 5% of the cases have characteristic clinical findings. One of the most important and earliest signs is prolonged jaundice during the neonatal period. We report herein a case of congenital hypothyroidism, who presented with icterus accompanied with sludge formation into the gallbladder, which disappeared after treatment with L-thyroxine.

Iodine and magnesium levels in maternal and umbilical cord blood of preeclamptic and normal pregnant women

The objective of this study was to investigate the relationship between preeclampsia and iodine levels and magnesium concentration in the blood of subjects in the northeast Anatolia region where iodine deficiency is common. Blood specimens were obtained from 24 preeclamptic and 16 healthy pregnant women. Iodine levels in blood were determined by the Foss method based on the Sandell-Kolthoff reaction. Serum protein-bound iodine (PBI) levels and magnesium concentration in maternal blood were lower in patients with severe preeclampsia compared to normal pregnant women (8.46 +/- 1.22 vs. 11.46 +/- 1.71 microg/dL, p < 0.001, 1.63 +/- 0.05 vs. 1.86 +/- 0.05 mg/dL, p < 0.001, respectively). Serum PBI levels and magnesium concentration in umbilical cord blood were higher in patients with severe preeclampsia than in normal pregnant women (8.84 +/- 1.9 vs. 7.33 +/- 1.07 microg/dL, p < 0.05, 2.48 +/- 0.03 vs. 2.02 +/- 0.01 mg/dL, p < 0.001, respectively). There was a positive correlation between the serum PBI levels in maternal blood and magnesium concentration in maternal blood in patients with severe preeclampsia (r = 0.41, p < 0.05). Thus, iodine may be one factor contributing to the pathophysiology of preeclampsia. Iodine supplementation may be effective therapy in preeclamptic in pregnant women.

Incidence of iodine deficiency in Turkish patients with congenital hypothyroidism

BACKGROUND

Turkey is located in an area of mild to moderate iodine deficiency. The aim of the present study was to investigate the incidence of iodine deficiency in patients with congenital hypothyroidism.

METHODS

Twenty five patients with a median age of 12 days (6 days-6 months) at diagnosis and followed for a median time of 7 months (1-60 months) were enrolled in the study. Thyroid function tests, thyroid scintigraphy, ultrasonography and urine iodine measurements of the patients and mothers were performed.

RESULTS AND CONCLUSION

Congenital hypothyroidism was diagnosed within postnatal day 13, between days 13 and 30, and after 30 days of age in 68%, 20% and 12% of the patients, respectively. At the time of diagnosis mean serum thyroid-stimulating hormone and total T4 were 85.3 +/- 27.6 mIU/L and 3.9 +/- 2.8 microg/dL, respectively. Incidence of iodine deficiency was 36% in the patients (median, 110 microg/L) and 88% in the mothers (median, 40 microg/L). Thyroid scintigraphy and ultrasound were normal in all of the patients with iodine deficiency. At scintigraphic evaluation, thyroid gland was not visualized in 28% of patients; in the patients whose thyroid glands were not visualized scintigraphically thyroid ultrasonography indicated agenesis in 57%, and hypoplasia in 43%. In all the patients with thyroid agenesis or hypoplasia iodine levels were normal. In 36% of the patients imaging studies of thyroid gland and urine iodine measurements were normal. Despite salt iodization program, incidence of iodine deficiency is still high in patients with congenital hypothyroidism and mothers. National measures are urgently required for correction of iodine deficiency in Turkey.

Iodine deficiency: an important and severe public health problem in Kayseri, Central Anatolia

Iodine deficiency (ID) remains a significant global public health problem. The iodine status of rural areas of Kayseri Province, Central Anatolia was previously evaluated but a screening survey covering both rural and urban populations had not been conducted. The aims of this study were: a) to determine the nutritional iodine status by calculating urinary iodine excretion (UIE) of the school-children living in the districts, city centre and villages of Kayseri Province; b) to implement preventive measures. The study group was made up of 1,784 school-children (920, 51.6% females; 864, 48.4% males), aged between 7 and 12 yr. Height and weight of children were measured and urine samples were collected. The median UIE of all school-children was 25.5+/-17.2 microg/l. Iodine status of the population was gauged based on median urinary iodine values categorised as normal (> or =100 microg/l), mild (50- 99 microg/l), moderate (20-49 microg/l) and severe (<20 microg/l) ID and classified according to age, gender and body mass index (BMI). While UIE of 289 school-children (16.2%) was in normal range (> or =100 microg/l), 747 of school-children (41.9%) had UIE <20 microg/l. Although there was no significant difference in UIE of female children based on their BMI (p>0.05), in overweight and obese male children UIE was significantly higher than in normal or underweight children (p<0.001). In Kayseri, moderate and almost severe ID affects public health from intrauterine to advanced stages of life. This is due to geographical characteristics of this area causing insufficient amounts of iodine in the drinking water and traditional nutritional habits of the families. The local "Iodine Monitoring Committee" developed an action plan including information/education/ communication activities to sustain monitoring so as to increase the inclusion of iodized salt in the region.

The impact of iodised salt or iodine supplements on iodine status during pregnancy, lactation and infancy

Objectives:Monitoring of iodine status during pregnancy, lactation and infancy is difficult as there are no established reference criteria for urinary iodine concentration (UI) for these groups; so it is uncertain whether iodized salt programs meet the needs of these life stages.

Design and Subjects:The method used in this paper was: 1) to estimate the median UI concentration that reflects adequate iodine intake during these life stages; and 2) to use these estimates in a review of the literature to assess whether salt iodisation can control iodine deficiency in pregnant and lactating women, and their infants.

Results:For pregnancy, recommended mean daily iodine intakes of 220-250 μg were estimated to correspond to a median UI concentration of about 150 μg l− 1, and larger surveys from the iodine sufficient countries have reported a median UI in pregnant women ≥ 140 μg l− 1. Iodine supplementation in pregnant women who are mild-to-moderately iodine deficient is beneficial, but there is no clear affect on maternal or newborn thyroid hormone levels. In countries where the iodine intake is sufficient, most mothers have median breast milk iodine concentration (BMIC) greater than the concentration (100-120 μg l− 1) required to meet an infant's needs. The median UI concentration during infancy that indicates optimal iodine nutrition is estimated to be ≥ 100 μg l− 1. In iodine-sufficient countries, the median UI concentration in infants ranges from 90-170 μg l− 1, suggesting adequate iodine intake in infancy.

Conclusions:These findings suggest pregnant and lactating women and their infants in countries with successful sustained iodised salt programs have adequate iodine status.

Iodine deficiency and goiter prevalence in Turkey after mandatory iodization

OBJECTIVE

The determination of (a) iodine deficiency, and (b) the relation between the iodized salt consumption in the Isparta province of Turkey.

METHODS

Five hundred students between 6-11 yr of age were evaluated. With a questionnaire, the subjects were asked whether they were using iodine-containing salt or not. After their body weight and height were measured, thyroid glands were examined with palpation, thyroid volumes were determined with ultrasonography (USG), and urinary iodine concentration was analyzed.

RESULTS

The median urinary iodine concentration (UIC) of children was 7.00 microg/dl. This value reveals that Isparta is a region with mild iodine deficiency. The total goiter prevalence was 30.4% with palpation and 26% with USG. The goiter prevalence by ultrasonography was 14.2% for the urban and 36.2% for the rural areas. This difference was statistically significant (p<0.05). The rate of total iodized salt consumption was 68%, which was not a satisfactory level. The consumption of iodized salt in the urban areas was significantly higher than that in rural areas (74 vs 62%, p<0.05). The median UIC value was 10.00 microg/dl in urban areas compared to 5.00 microg/dl in rural areas.

CONCLUSIONS

Our results indicate that although Isparta is a region with mild iodine deficiency, goiter prevalence remains a serious problem.