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Iodine deficiency disorderENDEMIC/DIFFUSE GOITERАУС-329 Д.ЭРДЭНЭТУЯА
Definition
Endemic goiter is a type of goiter that is associated with dietary iodine deficiency
Iodine deficiency is a lack of the trace element iodine
Iodine needs
WHO 1996Children Adult (>12 years old) Pregnant and
breastfeeding women
• 0-12 months 50mcg/day
• 2-6 years 90mcg/day• 7-12 years
120mcg/day
150 mcg/day 200 mcg/day
Endemic goiter
If the prevalence of goiter is more than 5% of the population (mostly children), it is considered an endemic goiter.
<5% no endemic 5-19.9% mild endemic 20-29.9% moderate endemic >30% severe endemic Mongolia is considered to have a mild endemic goiter. (7%)
Pathophysiology of Endemic goiter
Goiter: A swelling of the neck resulting from enlargement of the thyroid gland Iodine I2 (Iodide ion in food, such as in salt, Iodide bonds with Na+) is necessary for the
secretion of thyroid hormones (T4, T3). Iodine accounts for 65% of the molecular weight of T4 and 59% of the T3
The amount of TSH secreted by anterior pituitary is regulated by negative feedback loop. If the amount of T4 and T3 gets high, TSH secretion will be decreased
But in iodine deficiency there is very little amount of thyroid hormones, thus no inhibition of TSH production, leaving the anterior pituitary to produce TSH freely
Excess amount of TSH will cause thyroid gland cells to multiply and divide excessively resulting in goiter.
Iodine deficieny
Low level of T4 and T3
No inhibition of
TSH production
Too much TSH
production
Hyperplasia in thyroid
gland
Goiter
Causes/Risk factors
Low dietary iodine Iron and selenium deficiency (iron, selenium are contained in proteins that
are important for synthesis of thyroid hormones, for example peroxidases) Pregnancy Exposure radiation Increased level of goitrogens, such as some drugs and antibiotics (substances
that interfere with iodine uptake in the thyroid gland) Gender (higher occurrence in women) Oral contraceptives High consumption of conserved, pickled foods that contain thyrostatics
Signs and symptoms/ complaints/ consequences Fetus/Neonates• Cretinism (commonly characterised by mental deficiency, deafness,
squint, disorders of stance and gait, stunted growth and hypothyroidism)
• Increased prenatal and infantile mortality• Increased risk of deaf-mutism• Retarded bone growth
Children (Prevalence of iodine deficiency disorder is 28% among school age children/7-14 y.o/ in Mongolia )
• Goiter• Physical development delays• Mental development delays• Impaired sense of hearing and problems with speech• Paralysis of limbs
Pregnant women and women of child bearing age• Congenital anomalies• Reduced fertility• Irregular menstrual cycle• Increased incidence of spontaneous abortions• Still birth
Adults• Goiter• Reduced IQ (about 10-15 points)• Risk of compression of the upper airways• Increased risk of thyroid cancer• Hypothyroidism• Constipation• Dry, flaky skin• Generally inactive and sleepy• Cold intolerance
Diagnosis
1. Patient lives in a country with high iodine deficiency risk (mountanies regions and 3rd world countries)
2. Low level of median urine iodine 3. High absorption of radioactive iodine (I 131) during
scintigraphy 4. Goiter 5. Euthyroid or hypothyroid state 6.T4 synthesis ↓; T3 synthesis ↑ 7. TSH ↑
Median urine iodine (school aged children)
T3, T4, TSH, thyroglobulin level in blood
Volume of the thyroid gland
Absorption of J 131
• 100-200 mcg/L normal
• 50-99 mcg/L mild• 20-49 mcg/L
moderate• 20 mcg/L> severe
• T3, T4 close to normal or T4 slightly ↓, T3 slightly ↑ Euthyroid
• T4, T3 ↓, TSH ↑ Hypothyroidism
• TSH 3-5 IU/L normal, more than 5 IU/L infantile iodine deficiency
• More severe the iodine deficiency, higher level of thyroglobulin
• Adult male >25 ml (cm3)
• Adult female >18ml
2, 4, 24 hours later, the absorption will be increased up to 70-80%
Treatment
Drugs SurgeryIf drug treatment is ineffective, the size of the goiter is not loweringIf the size of the goiter is really largeNodule, malignancy
Euthyroid Hypothyroid-increase the intake of high iodine food (use of iodized salt)-iodine supplements (potassium iodide)-iodized oil
• L-Thyroxin 25-50mcg/ tab; daily dosage of 100-200mcg
• Triiodothyronine hydrochloride starting dosage: 2-5mcg/tab. Increase the dosage up to 50mcg/tab, 50-100mcg/day
• Thyreotom: 1 tab contains 40mcg T4, 10mcg T3. Start by 1/4 -1/8 of a tablet and increase to 1-1.5 tab/day.
Prevention
Public Risk groups: Pre school and school children, pregnant and breastfeeding women
Individual
Iodine fortified foods (salt, flour, sugar, water, tea etc)
• Antistruminum 1mg , 1 tab/day. 1-2 tabs/week
• KJ 100-150mcg 1-2 times/week
• Lipiodol 200mg, 1 capsule/6months. School children
• Lipiodol 400 mg/12 months
Person who is going to work and live in areas with iodine deficiency