Iodine Status in Swedish Lactating Women - Effect of Iodine Supplementation in the Thyroid Function of Mother and Infant
Iodine Status in Swedish Lactating Women - Effect of Iodine Supplementation in the Thyroid Function of Mother and Infant
The aim of the study is to measure urinary milk iodine concentration (MIC), iodine
 concentration (UIC), thyroid hormones (TSH, FT4) and thyroperoxidase antibodies (TPOab) in
 breast-feeding women, and UIC in their nursing infants to determine if the levels are
 adequate, and to see how they can be influenced by 150 ug daily iodine supplementation in
 breast-feeding women. The hypothesis is that there is a relative iodine deficiency in this
 sub-population - lactating women and nursing children-, and that this can be influenced by
 iodine supplementation. Adequate thyroid hormone and iodine levels are very important for
 small children, when the plasticity of the brain is greatest.

 This is as a prospective, double-blind, placebo-controlled study of 221 mothers and their
 infants. In parallel, 90 age-matched healthy non-pregnant women are recruited. Mothers are
 randomized to 150 µg/day iodide supplementation or placebo.

 Pregnant women are asked for participation on a visit in pregnancy week 37, at the mother
 health care (MVC) at Mölnlycke and Skövde. The study will run for approximately 3 months for
 each individual and begins by sampling A (UIC, TSH, FT4, TPOab) at week 37 of the pregnancy,
 when mothers also get randomized to 150 µg iodine or placebo. New sampling B (UIC, TSH, FT4,
 MIC ) is collected when the baby is 3 months old. Thereafter the study is completed. In
 parallel, 90 healthy non-pregnant, non-lactating women in the same age range are recruited
 and followed with UIC, TSH, FT4, TPOab for 6 months as a control group. In each case a simple
 questionnaire is filled and blood is also frozen for future analyses.
Are the mothers to be treated with 150 µg iodide per day during lactation to guarantee normal
 intake of iodine in breast-milk (MIC) and normal urinary iodine concentration (UIC) in their
 off-spring?

 Purpose and Aim This prospective, placebo-controlled study focus on the question whether
 lactating mothers shall add 150 µg iodide po to guarantee normal MIC and UIC levels in their
 children or not, as current iodinating program does not guarantee normal levels in these
 subgroups

 -  Primary aim: To compare the MIC and UIC of the children to lactating mothers receiving
 150 µg iodide or receiving placebo and compare to WHO recommendations.

 -  Secondary aim: To study UIC in the mothers during lactation compared to controls.

 To study the frequency of thyroid dysfunction in lactating women and whether it differs among
 patients on 150 µg or placebo.

 If the UIC concentration in the children breast fed by mothers receiving placebo is lower
 than the recommended levels by the WHO and if these levels are normalized with 150 µg iodide
 to the mother this study will be the supportive study for national authorities in Sweden,
 Europe and in the world to recommend all lactating mothers to add 150 µg when breast feeding
 even if the country is judged iodine sufficient.

 Survey of the field Iodine deficiency in the nature affects thyroid function The supply of
 iodine varies in different parts of the world, mainly because of varying levels of iodine in
 the ground water, different soils and plants, different distribution of sea-food, and
 dissimilar diary food consumption. In many areas with depleted soils and a long distance to
 the sea, iodine deficiency (ID) is still a major health problem.

 Adequate dietary iodine intake is essential for the production of thyroid hormones. Low
 iodine intake results in the development of hypothyroidism and goiter. Impaired production of
 thyroid hormones during pregnancy affects growth and brain development in the progeny. Iodine
 deficiency in school-age children impairs somatic growth, cognitive performance and motor
 function.

 Iodine insufficiency outside Sweden Iodine deficiency remains a public health problem in 47
 countries worldwide. Although most countries worldwide have implemented universal salt
 iodization , countries like Australia, New Zealand and several European countries have been
 reporting reoccurring iodine deficiency. Changes in food consumption patterns, legislation
 not covering processed food and decreased salt consumption impose new challenges in ensuring
 adequate iodine nutrition in the population.

 Iodine sufficiency in Sweden In Sweden, goitre was first described by Carl von Linné in 1747,
 and in the beginning of the 20th century, goitre was detected in 60% of cases in certain
 areas (19) and in 18% of the total population . A national survey conducted in 1929 confirmed
 endemic goitre regions located in the inner or eastern part of the country: these iodine
 deficient areas were known as the "goitre-belt".

 These observations contributed to initiation of the Swedish national iodine fortification
 program for salt in 1936. Initially, 10 mg of potassium iodide (KI) was added to every
 kilogram salt. In 1966, this was increased to the current level of 50 mg/kg salt, as goitre
 was still prevalent in some regions of the country.

 The first national evaluation of iodine status in Sweden was performed by our group according
 to the recommendations of the World Health Organization (WHO). Urinary iodine concentration
 (UIC) was measured in a representative national sample of children aged 6-12 years: the
 national median UIC was 125 μg/L, indicating optimal iodine nutrition . However, thyroid
 volumes were higher in Swedish school children than in the international reference study,
 which may be an effect from genetic and other environmental factors. Iodine intake is
 considered optimal in Sweden. These findings underline the importance of regular monitoring
 of iodine intake, especially concerning the decreased intake of table salt that is likely to
 follow health campaigns and patients with higher need of iodine may be at risk.

 Iodine demands increase during pregnancy and lactating The need of iodine is increased during
 pregnancy and lactating because of the increased thyroid hormone production and enrichment of
 iodine in breast-milk. An intake of iodide during pregnancy and breast feeding of 250 µg is
 recommended compared to 150 µg/day in the normal population. Severe iodine deficiency in the
 new-borne results in cretinism.

 The most critical period except for the prenatal period for the child is the two first years
 of life when the brain still develops. An enhanced risk period is the first 6 month of life
 when the child is breast-feeding. During this period the child is depending on the iodine
 concentration in the milk, which is a direct consequence of the mother iodine nutrition. When
 the infant starts to eat, iodide is supplied from the food.

 Numerous studies have measured both thyroid hormones and MIC in women living in iodine
 sufficient and insufficient regions, which are summarized in three reviews . Three studies
 have evaluated iodine nutrition in infants longitudinally , whereas the most recent from New
 Zealand is the longest; during 6 months maternal and infant iodine status were measured.

 In the world and the communities of thyroid disease the question is debated whether or not
 iodide shall be given to pregnant women. American thyroid Association (ATA) has made a strong
 recommendation for this in fear the even mild iodine deficiency in small children may affect
 the brain development negatively. WHO has modified their guidelines of supplementation to
 whether the nation is regarded iodine sufficient, including sufficient levels in pregnant and
 lactating women (category 1), where no iodide supplementation is need, or not sufficient. The
 latter group is divided in two; one group where most patient, but <90%, eat iodinated salt
 and UIC <100 (category 2) and one group with similarly low UIC but where iodized salt is
 scarcely used (category 3). An iodine supplement of 150 µg is the recommendation in these
 countries. However, in 2010 Mulrine et al performed a placebo controlled study the first 6
 months postpartum. The mothers were iodine deficient, as New Zealand had not implemented an
 iodizing program, and were supplemented with 75 or 150 µg/day. Both mother and child had UIC
 and MIC lower than recommend by the WHO. The authors encourage a study done in the
 circumstances of iodine sufficiency in the nation.

 Data from pregnant and lactating women in Sweden are scares. Two small local studies reports
 median UIC 145-178 µg/dag and 89 µg/l during pregnancy. More knowledge is needed to judge if
 Swedish woman shall have and iodine supplementation of 150 µg/day or not during this
 vulnerable period of life for their children.

 Project description Study design This is a prospective, double-blinded placebo-controlled
 trial of 221 lactating women and their children. Mothers are randomized to 150 µg/day iodine
 supplementation or placebo for 15 weeks. In parallel 90 healthy female controls are recruited
 from the same community stratified for age and smoking habits. Patients are included after
 week 36 in pregnancy by the midwife and urinary iodine concentration (UIC), thyroid hormones
 levels and thyroperoxidase antibodies (TPO-ab) are assessed and a simple questionnaire is
 filled in by the pregnant women. Placebo/iodine is started at the same visit (allocation
 1:1). At the visit 13 (13±1) weeks postpartum UIC, thyroid hormones levels and
 thyroperoxidase antibodies (TPO-ab) are assessed in all mothers and a simple questionnaire is
 filled in. MIC is measured in those who still breast-feed. UIC is measured in babies. At all
 occasion blood specimens are taken, blood is also frozen for future analyses. Weight and
 length are registered postnatal in the child.

 Study population Patients At the antenatal care unit at Mölnlycke and Skövde Health Care
 center 221 pregnant women aged 18-40 years will be collected consecutively according to
 inclusion and exclusion criteria.

 Inclusion criteria: Pregnant ≥36 weeks, Singleton pregnancy, Aged 18-40 years, Intend to
 breast-feed, Agree to take no iodine containing supplements during the study postpartum
 except for study medication, No current thyroid disease Exclusion criteria: Patient who may
 not attend to the protocol according to the investiga¬tor's opinion, Plans of another
 pregnancy within the first 6 months postpartum, Vegans

 Controls Controls are collected from a randomized sample attain by the Swedish Tax Agency of
 premenopausal women from Mölnlycke community. Controls in the same age as the patients are
 contacted by mail for participation in the study and if smoking habits agree with the
 corresponding patient they come for an inclusion visit. If interested, the controls are told
 to stop any other iodine containing supplements 1 week before the first visit. If no answer,
 a reminding letter is sent after two weeks.

 Inclusion criteria: Aged 18-40 years, Agree to take no iodine containing supplements during
 the study postpartum. No current thyroid disease Exclusion criteria: Controls who may not
 attend to the protocol according to the investiga¬tor's opinion, Plans pregnancy within the
 next 6 months, Vegans

 Significance If the study proves that supplement of 150 µg iodine to mothers guarantee normal
 iodine intake in the newborn child contact will be taken with the National Food Agency, the
 National Board Health and Social welfare and the government to lobbying for a general
 directives of iodine supplementation to all lactating women.
LACTATING WOMAN:

 Inclusion Criteria:

 -  18-40 years.

 -  Pregnancy longer than week 36.

 -  Single Pregnancy.

 -  Planned breastfeeding.

 -  No current thyroid disease.

 -  Agree not to take iodine supplementation except as provided through the study.

 Exclusion Criteria:

 -  Patient who is not expected to adhere to the research protocol. Plans for pregnancy
 within 6 months after delivery.

 -  Vegans.

 CONTROL WOMAN:

 Inclusion Criteria:

 -  18-40 years.

 -  No current thyroid disease.

 -  Agree not to iodine supplementation during the study.

 Exclusion Criteria:

 -  Patient who is not expected to adhere to the research protocol.

 -  Plans for pregnancy within 6 months of study entry.

 -  Vegans.