https://www.thelancet.com/pdfs/journals/lancet/PIIS0140-6736(07)61693-6.pdf

What works? Interventions for maternal and child undernutrition and survival.

Food and Agricultural Organization of the United Nations PA N I S F I A T G u id e in e s o n fo o d fo r tific atio n w th m ic r o n u tr ie n ts Interest in micronutrient malnutrition has increased greatly over the last few years. One of the main reasons is the realization that micronutrient malnutrition contributes substantially to the global burden of disease. Furthermore, although micronutrient malnutrition is more frequent and severe in the developing world and among disadvantaged populations, it also represents a public health problem in some industrialized countries. Measures to correct micronutrient deficiencies aim at ensuring consumption of a balanced diet that is adequate in every nutrient. Unfortunately, this is far from being achieved everywhere since it requires universal access to adequate food and appropriate dietary habits. Food fortification has the dual advantage of being able to deliver nutrients to large segments of the population without requiring radical changes in food consumption patterns.

Guidelines on food fortification with micronutrients

I. Introduction II. The Regulation of Thyroid Function in Normal Pregnancy A. The thyroid hormone transport proteins B. The thyroid hormones 1. Total thyroid hormones 2. Free thyroid hormones 3. Peripheral metabolism of thyroid hormones C. The serum levels of thyroglobulin (TG) D. The metabolism of iodine E. The hypothalamic-pituitary control of thyroid function and the role of hCG 1. Hypothalamic-pituitary-thyroid axis (HPTA) 2. Regulation of serum TSH 3. Thyrotropic action of hCG F. A global view of thyroidal economy in pregnancy III. Pathological Alterations of Thyroidal Regulation Associated with Pregnancy A. IDD 1. Consequences of iodine deficiency during pregnancy 2. Assessment of increased thyroidal stimulation 3. Gestational goitrogenesis and its prevention by iodine supplementation 4. Consequences of iodine deficiency for the offspring B. Hypothyroidism and pregnancy 1. Fertility and pregnancy outcome in hypothyroid women 2. Thyroid hormone replacement in the hypothyroid pregnant woman 3. Subclin...

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The Regulation of Thyroid Function in Pregnancy: Pathways of Endocrine Adaptation from Physiology to Pathology

Summary OBJECTIVE To evaluate the impact of maternal hypothyroxinaemia during early gestation (fT4 below the lowest tenth percentile and TSH within the reference range: 0·15‐2·0 mIU/l) on infant development, together with any subsequent changes in fT4 during gestation. DESIGN A prospective 3-year follow-up study of pregnant women and their children up to the age of 2 years. MEASUREMENTS Child development was assessed by means of the Bayley Scales of Infant Development in children of women with hypothyroxinaemia (fT4 below the tenth percentile at 12 weeks’ gestation) at 12 weeks’ gestation (cases), and in children of women with fT4 between the 50th and 90th percentiles at 12 weeks’ gestation, matched for parity and gravidity (controls). Maternal thyroid function (fT4 and TSH) was assessed at 12, 24 and 32 weeks’ gestation. The mental and motor function of 63 cases and 62 controls was compared at the age of 1 year, and of 57 cases and 58 controls at the age of 2 years. RESULTS Children of women with hypothyroxinaemia at 12 weeks’ gestation had delayed mental and motor function compared to controls: 10 index points on the mental scale (95% CI: 4·5‐15 points, P = 0·003) and eight on the motor scale at the age of 1 year (95% CI: 2·3‐12·8 points, P = 0·02), as well as eight index points on the mental (95% CI: 4‐12 points, P = 0·02), and 10 on the motor scale (95%CI: 6‐16 points, P = 0·005) at the age of 2 years. Children of hypothyroxinaemic women in whom the fT4 concentration was increased at 24 and 32 weeks’ gestation had similar scores to controls, while in the controls, the developmental scores were not influenced by further declines in maternal fT4 at 24 and 32 weeks’ gestation. CONCLUSIONS Maternal hypothyroxinaemia during early gestation is an independent determinant of a delay in infant neurodevelopment. However, when fT4 concentrations increase during pregnancy in women who are hypothyroxinaemic during early gestation, infant development appears not to be adversely affected. In the past decade, interest has been rekindled in the relationship between maternal plasma thyroid hormone concentration during pregnancy and subsequent infant neurodevelopment (Pop et al ., 1995, 1999a; Haddow et al ., 1999; Lazarus, 1999; Smit et al ., 2000). It is well known that both maternal thyroid dysfunction during pregnancy (especially hypothyroidism) and severe iodine deficiency adversely affect the outcome of neurodevelopment in children (Delange, 1994; Glinoer, 1997; Mestman, 1999). Even in areas in which there is sufficient iodine intake in the general population, pregnant women often have fT4 plasma levels in the lower ranges, without elevated TSH. This is defined as hypothyroxinaemia, and is generally regarded as a normal condition. However, there is growing concern that hypothyroxinaemia during early gestation could be harmful to the offspring (Pop et al ., 1999b; Utiger, 1999; Morreale de Escobar et al ., 2000). In fact, little is known about maternal fT4 levels during normal pregnancy, or their relationship to the development of the child. This paper describes the results of a longitudinal prospective study that investigates whether maternal thyroid hormone levels, assessed in women without (sub)clinical thyroid function at three different trimesters during pregnancy, are adversely related to child development at 1 and 2 years of age.

Maternal hypothyroxinaemia during early pregnancy and subsequent child development: a 3-year follow-up study

Thyroid hormones are essential for growth, neuronal development, reproduction and regulation of energy metabolism. Hypothyroidism and hyperthyroidism are common conditions with potentially devastating health consequences that affect all populations worldwide. Iodine nutrition is a key determinant of thyroid disease risk; however, other factors, such as ageing, smoking status, genetic susceptibility, ethnicity, endocrine disruptors and the advent of novel therapeutics, including immune checkpoint inhibitors, also influence thyroid disease epidemiology. In the developed world, the prevalence of undiagnosed thyroid disease is likely falling owing to widespread thyroid function testing and relatively low thresholds for treatment initiation. However, continued vigilance against iodine deficiency remains essential in developed countries, particularly in Europe. In this report, we review the global incidence and prevalence of hyperthyroidism and hypothyroidism, highlighting geographical differences and the effect of environmental factors, such as iodine supplementation, on these data. We also highlight the pressing need for detailed epidemiological surveys of thyroid dysfunction and iodine status in developing countries.

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Global epidemiology of hyperthyroidism and hypothyroidism.

The prevention of iodine deficiency is still a worldwide concern. This study, conducted in Soja in western Sudan, was carried out to evaluate the effects of a dose of iodized oil sufficient enough to give maximum protection against goiter and provide an acceptable iodine supply without side-effects over a sufficiently long period of time. Adult goitrous subjects (n = 117) were randomly assigned to three groups, A, B, and C, and received a single oral dose of 200, 400, or 800 mg iodine, respectively. Urine and blood samples were collected at the start of the study and monitored for 1 yr. In the 3 groups, mean serum T4 and median urinary iodine and serum TSH values were restored to reference limits, and these were maintained for about 1 yr. In each treatment group, about two thirds of the subjects displayed a reduction in goiter size, and the 400- and 800-mg doses were not more efficient than the 200-mg dose to accomplish normalization of thyroid hormone values. A temporary rise in TSH was noted 1 week after iodine administration in 1, 3, and 10 subjects, respectively, and 1, 0, and 3 subjects showed biochemical signs of thyrotoxicosis during the year after treatment with the 3 different doses. The data indicate that oral administration of 200 mg iodine is effective and acceptable for treating iodine deficiency in adults for 1 yr. Because of the risks of side-effects and the shortage of medical resources, higher doses are not recommended.

The effects of different doses of oral iodized oil on goiter size, urinary iodine, and thyroid-related hormones.

Changes in iodine metabolism during late pregnancy and lactation: a longitudinal study among Sudanese women

Changes in iodine metabolism during late pregnancy and lactation: a longitudinal study among Sudanese women.

Salt iodination is the method of choice for prevention of iodine deficiency in most parts of the world. However, establishment of such a program frequently involves considerable changes in the marketing and distribution patterns and requires years to achieve. This study was conducted to evaluate the efficiency of using well-defined water sources containing iodine-saturated silicon matrices for providing adequate iodine supply to an iodine deficient population in Kordofan State, Western Sudan. A system of water iodination using silicon matrices containing 30% sodium iodide placed in polyethylene baskets was used in four villages using either traditional wells or hand pumps. Before and every 6 months after iodination of water, urine and blood samples were obtained for determination of iodine and thyroid-related hormones, respectively. Goitre assessment on the village populations were performed at the start and 2 years later. Improvements in iodine status were recorded in all the study villages. The water iodine concentrations increased and a higher iodine content was observed in the hand pumps compared to the traditional wells. The median urinary iodine concentrations increased significantly, from 0.19, 0.20, 0.19, 0.11 to 1.20, 1.10, 0.37, 0.30 mumol/l in the four villages, respectively. The percentages of subjects with serum TSH above 4 mU/l were decreased from more than 30% before iodination to less than 15% at 2 years after iodine supply and the mean serum thyroxine hormone values rose. The rates of goitre decreased from 69% to less than 25%. The study shows that this system is effective, cheap, safe and practically applicable under conditions prevailing in rural areas in developing countries with iodine deficiency.

Control of iodine deficiency using iodination of water in a goitre endemic area.

OBJECTIVES: Data on neonatal and maternal thyroid function during labour in a mild iodine deficiency endemic area are lacking. The current study focuses on elucidating the thyroid function during labour in a group of pregnant women who live in an area of mild iodine deficiency in Sudan compared to that observed in their corresponding newborns. MEASUREMENTS: Serum concentrations of TSH thyroglobulin (Tg) triiodothyronine (T3) and free thyroxine (FT4) were investigated during labour in a group of mothers and their neonates residing in an area with mild iodine deficiency in Sudan (n = 76 mother-newborn pairs). DESIGN: Maternal blood samples were taken on two occasions: first during the third trimester of pregnancy (weeks 32-39); and second just before delivery. Cord blood samples were obtained by a doctor or a trained midwife during delivery. RESULTS: The median concentrations (and interquartile ranges) of neonatal TSH Tg T3 and FT4 were 6.8 (4.7-12.4) mU/l 61 (40.2-98.2) mcg/l 0.9 (0.8-1.2) nmol/l and 14.2 (13.4-15.9) pmol/l respectively. The corresponding levels for the mothers during labour were 2.3 (1.9-3.2) mU/l 33 (15.0-56.8) mcg/l 2.6 (2.0-2.9) nmol/l respectively. The median neonatal serum concentrations of TSH Tg and FT4 were significantly higher than the corresponding maternal levels (P < 0.0001 P < 0.0001 P < 0.0001 respectively). In contrast the median maternal serum concentration of T3 was significantly higher than that of the neonates (P < 0.0001). When the different neonatal thyroid parameters were compared with each other significant correlations were observed between TSH and FT4 (r = 0.4 P = 0.001); Tg and T3 (r = -0.3 P = 0.04) and Tg and FT4 (r = 0.5 P = 0.0001). Women with Tg concentrations above 20 mcg/l showed a higher median FT4 concentration than those with Tg concentrations below 20 mcg/l (P < 0.001 P < 0.001 respectively). Nevertheless the thyroid function of neonates born of mothers with elevated Tg was similar to that of neonates born of mothers with low Tg levels. No significant changes had occurred in the thyroid function parameters between the third trimester of pregnancy and during the time of labour. The thyroid function indicators of the babies born by vaginal delivery did not differ significantly from those of the babies born by Caesarian section. CONCLUSIONS: The study suggests that in areas with mild iodine deficiency neonates may be at the limit of decompensation as evidenced by their enhanced TSH and Tg levels as well as increased T4 compared to their mothers. This finding must not create a false sense of well-being and points rather to the urgency of iodine supplementation of mothers even in areas with mild iodine deficiency as in this part of Sudan. The mode of delivery whether by spontaneous vaginal delivery or Caesarian section did not seem to affect the thyroid function of the newborn. (authors)

Thyroid function in the newborn in relation to maternal thyroid status during labour in a mild iodine deficiency endemic area in Sudan

The use of sugar as a vehicle for iodine supplementation was explored in a study of iodine deficiency in the Sudan. A survey of sugar consumption was conducted and established a widespread and uniform intake of sugar in all ages with no differences among socio-economic groups. The daily intake among adults varied from 48 g to 78 g as examined in five different geographical areas in the country. Iodinated sugar was produced by addition to sugar solution prior to crystallisation in an evapocrystallizer or sprayed on the conveyor of cured sugar before it entered the dryers. Subsequently, the iodinated sugar was given to members of 18 and 60 families in a mildly (urinary iodine <5.1 μg/dl) and moderately (urinary iodine <3 μg/dl) iodine deficient areas, respectively, over a 1-month and a 6-month period, respectively. In both tests, improvements were recorded, i.e. the rates of goitre decreased, urinary iodine levels increased significantly (from 5.1 to 14.4 μg/dl and from 3 to 9.8 μg/dl, respectively) and thy...

M Eltom

Papers

The effects of different doses of oral iodized oil on goiter size, urinary iodine, and thyroid-related hormones.

Changes in iodine metabolism during late pregnancy and lactation: a longitudinal study among Sudanese women.

Control of iodine deficiency using iodination of water in a goitre endemic area.

Thyroid function in the newborn in relation to maternal thyroid status during labour in a mild iodine deficiency endemic area in Sudan

The use of sugar as a vehicle for iodine fortification in endemic iodine deficiency