Iodine toxicity

Iodine toxicity
R2 ณัฐพงศ์ เลาห์ทวีร่งุ เรือง
R2 พรทิพย์ ธีระวิทย์
Iodine
 Iodine (I), chemical element, a member of the halogen
element (Group VIIa)
 The name iodine, from the Greek for violet
 First description by Bernard Courtois in 1811
 Violet vapor arising from seaweeds ash during the
manufacture of gunpowder
Iodine
http://global.britannica.com/EBchecked/topic/292625/iodine-I
http://commons.wikimedia.org/wiki/File:IodoAtomico.JPG
Source of iodine
Iodine
 Iodine is a vital micronutrient required at all stages of life
 It is a trace element, just 5 gm of which are sufficient to meet
the life-time needs of an individual with a life-span of 70
years
 A healthy adult body contains 15-20 mg of iodine, 70-80% of
which is stored in the thyroid gland
Dhaar GM, Robbani I. Foundations of Community Medicine. India: Reed Elsevier; 2008.
Nutritional problems of mothers and children. pp. 272–280.
Detels R, Holland WW, Mc Ewen HJ, Omenn GS. Oxford Textbook of Public Health. 3. Oxford University Press; 1977.
Endocrine and metabolic disorders; pp. 1114–1115.
Iodine
• Daily intake of iodine by an individual amounts to 500
micrograms
• Daily physiological requirement during adult life is 150
micrograms; during pregnancy and lactation period is 200
micrograms; and during neonatal period is 40 micrograms
• Normally about 120 micrograms of iodide are taken up by
the thyroid gland for the synthesis of thyroid hormones
Khurana I. Textbook of Medical Physiology. India: Reed Elsevier; 2006. Endocrinal System; pp. 710–715.
Pal GK. Textbook of Medical Physiology. India: Ahuja Publishing House; 2007. Endocrine Physiology; p. 346.
Urinary iodine concentration
Source of Iodine
 Trace amounts, mainly as iodide salts
 Found in
 seawater 50-60 mcg/L
 freshwater 1-10 mcg/L
 soils 10mcg/kg
 food source
Source of iodine
Iodine containing drug
• Iodine Tincture : Solution, topical 2% iodine and 2.4% sodium
•
•
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•
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iodide in 47% alcohol, purified water
Iodopen : Injection 100 mcg/mL (as sodium iodide 118
mcg/mL)
Iosat : Tablets, oral potassium iodide 130 mg
Pima : Syrup, oral potassium iodide 325 mg per 5 mL
SSKI : Solution, oral potassium iodide 1 g/mL
Strong Iodine (Lugol's Solution) : Solution, oral iodine 5%
(50 mg/mL) and potassium iodide 10% (100 mg/mL) in water
ThyroSafe : tablets, oral potassium iodide 65 mg
ThyroShield : Solution, oral potassium iodide 65 mg/mL
Amiodarone : tablet, 37% iodine (75mg, 7.5 mg free iodide)
Iodine toxicity
 The term iodine excess refer to increases in intake relative
to estimated physiological requirements.
 The National Research Council (NRC) Recommended
Dietary Allowance (RDA) for iodine is 150 μg/day (2.1
μg/kg/day for a 70-kg adult), with additional allowances of
25 and 50 μg/day during pregnancy and lactation
Iodine toxicity
 Oral exposure: ingestion
 Corrosive gastroenteritis, pharynx swelling
 Vomiting, hematemesis, diarrhea
 Vomitus may be blue
 Inhalation exposure: iodine vapor
 severe pulmonary irritation, pulmonary edema
Iodine toxicity(extrathyroidal effect)
 Skin and eyes exposure
 Corrosive burn
 Sialadenitis
 Ioderma
 Transplacental transmission
 Neonatal hypothyroidism and death
 Chronic exposure
 Thyroid dysfunction
Iodine-induced thyroid dysfunction
 Iodine induced hypothyroidism
 Iodine induced hyperthyroidism
Leung, A. M. & Braverman, L. E. Nat. Rev. Endocrinol. 10, 136–142 (2014)
Thyroid hormone synthesis
Iodine-induced hypothyroidism
Wolff-Chaikoff effect
Escape mechanism
Leung, A. M. & Braverman, L. E. Nat. Rev. Endocrinol. 10, 136–142 (2014)
Iodine-induced hypothyroidism
Risk factors
1. Underlying thyroid diseases
a)
b)
c)
d)
e)
f)
g)
Euthyroid Graves’ disease previously treated
Hashimoto’s thyroiditis
History of subacute thyroiditis
History of postpartum thyroiditis
History of AIT type 2
Post hemithyroidectomy
After interferon-α therapy
Curr Opin Endocrinol Diabetes Obes 2012, 19:414–419
Iodine-induced hypothyroidism
Risk factors
2. Fetus in utero
3. Individual given other potential goitrogens: lithium
Curr Opin Endocrinol Diabetes Obes 2012, 19:414–419
Iodine-induced hyperthyroidism
 Risk factors
1.
2.
History of nontoxic diffuse or nodular goiter
Long standing iodine deficiency
Curr Opin Endocrinol Diabetes Obes 2012, 19:414–419
Iodine-induced hyperthyroidism
Mechanism
 Jod-Basedow phenomenon
 Autonomous thyroid nodule
 Autoimmune thyroid disease
Curr Opin Endocrinol Diabetes Obes 2012, 19:414–419
Diagnosis
 History of exposure
 Evidence of corrosive injury :
 Mucous membrane are usually stained brown.
 Vomitus may be blue.
 Blood level are not clinically useful but may confirm
exposure.
Treatment
 Emergency and supportive measures
 Maintain airway
 Treat pulmonary edema and bronchospasm
 Specific drugs and antidote
 Sodium thiosulfate is not recommended.
 Decontamination
 Do not induce vomiting.
 Starchy food, activated charcoal
 Enhance elimination
 Not recommended
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