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