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Iodine deficiency disorders Iodine is an essential component in thyroid hormone production Thyroid hormone regulates basic metabolism :energy consumption, cellular activity, growth and in particular brain development. Hypothyroidism: slow, cold, sluggish brain function, short stature, mental and motor development delayed or slowed. In extremes general neurological development delayed. Hormone regulation Hypothamalus TSHRF - Somatostatin Hypofysis T4 T3 TSH T3 T4 I pool Hormones and iodine deficiency Spectrum of disease Table 1. The Spectrum of Iodine Deficiency Disorders, IDD. Fetus Abortions Stillbirths Congenital anomalies Increased perinatal mortality Endemic cretinism Neonate Neonatal goiter Neonatal hypothyroidism Endemic mental retardation Increased susceptibility of the thyroid gland to nuclear radiation Child and Goiter adolescent (Subclinical) hypothyroidism Impaired mental function Retarded physical development Increased susceptibility of the thyroid gland to nuclear radiation Adult Goiter with its complications Hypothyroidism Impaired mental function Spontaneous hyperthyroidism in the elderly Iodine-induced hyperthyroidism Increased susceptibility of the thyroid gland to nuclear radiation Adapted from Hetzel (1), Laurberg et al. (52, 171) and Stanbury et al. (158). Importance of the problem Prevalence 1 billion persons exposed 200 million persons affected (goitres) 26 million cases of mental problems 6 million cases of cretinism Goitre Increase in size four to five times distal phalanx of the thumb Aesthetic Compression Related hypothyroidism: is not a compensation cancer Iod Basedow (hyperthyroidism) due to hyperstimulation, mutation autonomous nodules Iodine deficiency and the foetus Brain development fast between 3-5 months pregnancy and from third trimester till end of second year Maternal T4 essential for first 24 weeks Foetal T4 starts at 24 weeks 30% cord blood is of maternal origin Iodine and the neonate Perinatal mortality Infant mortality Low birth weight Brain development needs T4 Iodine deficiency mental retardation, retarded motor development. General IQ decrease of 15 Points Iodine deficiency and adults Lack of energy apathy, slow brains goitre and mechanical complications Nodular thyroid hyperthyroidism Pregnancy and cretinism Aethiology Low iodine uptake. Soil dependent erosion, wash away: deltas Goitrogens Manioc: linnamarin thiocyanate Blocs uptake of Iodine at the thyroid, competitive inhibition Traditional preparations Konzo Brassica family polutants IDD and selenium deficiency Se part of peripheral type I de-Iodinase (kidney and liver) Se deficiency: slower T4 to T3 metabolisation Se part of Glutathion peroxidase : protector of H2O2 damage Thyroid damage, disfunction of thyroid Cerebral de-iodinase is not Se dependent Glutathion peroxidase stimulates T4 production Iodine needs RECOMMENDED INTAKE ug/day 0 - 6 months 35 6 - 12 months 1 - 10 years >= 11 years pregnancy – lactation 45 60 – 100 100 - 115 125 - 150 8 ug/kg 5 ug/100ml of milk 7 ug/100 kcal Diagnosis of endemicity Prevalence of goitre Dosage of urinary iodine TSH dosage Prevalence of cretinism Prevalence of goitre Class Description 0 Absence of goitre Ia Detectable goitre only by palpation and invisible, even when the head is stretched. More voluminous thyroid than usual, the lobes have a volume that is at least equal to the volume of the last phalanx of the subject’s thumb. Ib Palpable and visible goitre when the head is stretched. Also all the cases where there is a nodule - even when there is no goitre. II Visible goitre when the head is in a normal position. III Very big goitre, visible from a distance IODE DEFICIENCY SEVERE MODERATE MILD > 50 % > 10 % 20-49 % 10-19 % 5-9 % 1-5 % Number of cases of goitre among the school children (6-12) visible goitre total goitre Urinary Iodine Reflects directly intake Is best to follow up programme response, goitre takes time to decrease in size Samples needed are smaller Technique is simple and not expensive Samples can be taken easily, cheap, acceptable and don’t need conservation techniques Table 5. Epidemiological criteria for assessing iodine nutrition based on median urinary iodine concentrations in schoolaged children Median Iodine intake Iodine nutrition urinary (µg/L) iodine < 20 Insufficient Severe iodine deficiency 20-49 Insufficient Moderate iodine deficiency 50-99 Insufficient Mild iodine deficiency 100-199 Adequate Optimal 200-299 More than adequate Risk of iodine-induced hyperthyroidism within 5-10 years following introduction of iodized salt in susceptible > 300 Excessive Risk of adverse health consequences (iodine-induced hyperthyroidism, autoimmune thyroid diseases) From WHO/UNICEF/ICCIDD (2) Endemic cretinism Neurological Severe motor and mental deficit cerebral palsy deafness, mutism euthyroid Myoedematous Severe mental deficit Hypothyroid, destruction of the thyroid Iodine deficiency combined with goitrogens and Se deficiency Control strategies Supplementation: injections, oral Fortification changing food habits Supplementation Need to start early in pregnancy supplement women of child bearing age Operational difficulties Injections and hepatitis and HIV Covers need for about 4 years injections Oral covers needs for one year Fortification Add iodine to a vehicle: salt or water Additive must be stable, not change the carrier No by-pass, centralised production Need for a comprehensive approach Packaging, evaporation Access of all the population to the fortified food Policy and protection of the market Who pays? Success story of Iran Food habits Very limited approach, food reflects iodine soil content Control complications Need for intensive follow up Changing consumption patterns in salt Variations in salt consumption Transient hyperthyroidism