Iodine Deficiency Disorder, IDD


## Basic introduction

  • Despite being highly preventable, iodine deficiency is still the world’s most common cause of brain damage (with 54 countries still being iodine-deficient)a
  • Iodine is required for synthesis of thyroxine (T4) and triiodothyronine (T3) - the two active forms of thyroxine
  • The population living far from the sea and at higher altitudes are at particular risk of IDD
  • Pregnant and lactating mothers have higher nutritional requirements of iodine than other population groups

## Risk factors for IDD

  • Low dietary iodine
  • Pregnancy
  • Increased intake of goitrogens e.g. perchlorates, thiocyanates, calcium, and smoking tobacco
  • Exposure to radiation
  • Selenium deficiency

## Statistics

  • Daily intake requirement of iodine in the general population - 150 mcg/day
  • Daily intake requirement of iodine in pregnancy - 220 mcg/day
  • Daily intake requirement of iodine during lactation - 290 mcg/day
  • Target quantity of iodine in the fortified salt - 70 mcg/g
  • In 1994, 16% of children 8-10 years in Kenya had goiterb
  • It is estimated that 66% of households globally have access to iodized salta
  • Mild or moderate deficiency may result in colloid goiter (thyroid gland hypertrophication in an effort to produce more thyroxine, with most patients remaining euthyroid)
  • Hypothyroidism in case of severe deficiency
  • Infant mortality
  • Still birth
  • Cretinism (due to untreated hypothyroidism in pregnancy)
  • Intellectual disability
  • Lethargy
  • Delay mental and physical development (including short stature)
  • Weight gain
  • Myalgia
  • Joint pains
  • Macroglossia and resultant effects on the speech
  • Apnoiec attacks
  • Constipation
  • Amnesia
  • Disturbance of menstrual cycle
  • Blurred vision
  • Psychiatric manifestations
  • Reduced fertility
  • Large abdomen
  • Umbilical cord hernia
  • Somnolence
  • Cold intolerance
  • Dry hair
  • Challenges in feeding
  • Bradycardia
  • Dry skin
  • Hoarse voice
  • Myxedema (non-pitting edema)
  • Pitting edema
  • Hypotension
  • Clinical review, especially thyroid gland examination
  • TSH assays (elevated TSH).
  • Measurement of iodine in urine (using sadell Kolthoff among others)
  • Free thyroxine, T4, or the free thyroxine index, FTI (reduced levels)
  • Full Blood Count, FBC
  • Imaging tests
  • Hypothyroidism due to other causes such as drug-induced hypothyroidism and auto-immune antibodies among others
  • Anemia
  • Depression
  • Alzheimer
  • Fortifying of table salts with iodine

(The World is almost eliminating iodine deficiency using this method)a

  • Through the support of WHO, most countries globally have set up permanent national salt iodization programmes a
  1. WHO (2017) Access on 24th March 2017
  2. Kenya Nutrition Profile – Food and Nutrition Division, FAO, 2005
  3. Stephanie L. Lee; Elizabeth N. Pearce; Sonia Ananthakrishnan (16 December 2015). "Iodine Deficiency". Medscape. Retrieved 2016-12-11.
  4. Kenyan Ministry of Health. Clinical guidelines for management and referral of common conditions at levels 4-6. Hospitals. 2009; 3:259-261.
  • Iodine supplementation (with iodized salt, seaweed, salt water fish, milk, and eggs) - goiters caused by iodine deficiency decrease in size in very young children and pregnant women
  • Iodine deficiency that has been there for long time may not respond well to iodine supplementation and hyperthyroidism may occur

## Management of arising hypothyroidism:

  • Levothyroxine (l-thyroxine) at the following dose:

_Neonate: Tabs 10µg/kg/day (increased at a dose of 5µg/kg/day fortnightly to max. dose 25-37.5µg/day).

_Children one month to 12yrs:  Tabs 5-10µg/kg/day (increased at a dose of 25µg/kg /day2-4 weekly.

_Children 12-18yrs:  Tabs 50-100µg/day (increased at a dose of 50µg/day 3-4 weekly to a maintenance dose of 100-200µg/day

  • For myxedema coma: T4 IV and corticosteroids and other supportive measure.
  • After stabilization of dosage, patients need to be reviewed annually
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