sec 1 IDD

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IDD is very widespread; over 572 million people have goitre, 13.6% of the world’s population

Almost any population that is not using iodized salt is likely to be iodine deficient; if goitre exists in the population, it is of crucial importance to ensure iodine adequacy of women of reproductive age.

Causes

Infants-

Iodine deficiency in the mother late in pregnancy
Lack of iodine in the breast milk
Weaning baby from the breast with improper dietary supplementation

Children and adults-

Lack of iodine in food for a prolonged time period

since the thyroid gland can store iodine, it is capable of producing thyroid hormones for months after the individual has stopped eating food containing iodine

once the thyroid is depleted of iodine reserve and unless iodine intake has increased, then signs of deficiency will appear

Manifestations

Infants-

Babies with hypothyroid cretinism may not feed well or gain weight, are constipated, feel cold or appear sleepy; have thick dry skin, a hoarse cry, poor cognitive function, or develop slowly.

Babies with neurological cretinism have squinted eyes, deafness, mutism, weakness and stiffness of the legs, or poor cognitive function.

Children-

Slow physical development or growth, might be stunted
Poor mental acuity and function
Goiter (enlarged thyroid gland) especially during adolescence

Pregnancy-

Miscarriages or stillbirths
Low birth weight or congenital abnormality
Baby may have neurological or hypothyroid cretinism
Goiter enlargement through progression of pregnancy

Adults-

Goiter
Person feels cold easily or lacks energy (sleepy)
Poor cognitive ability
Person has dry skin or constipation

Indicators

Process and Outcome Indicators of Iodine Deficiency Disorders

Indicator type		Indicator
Process and Other Non-Outcome Indicators (process indicators in bold)		Dietary intake – consumption of seafoods, food grown/raised in iodine rich soil or iodine fortified foods and consumption of goitrogens, usually a more general assessment of environmental risk is used instead of FFQ and recall Salt /Other food Or Water Fortification With Iodine – use of dietary intake of fortified foods (usually salt) is common, as well as testing salt for iodine at the factory and household level Iodine Supplementation - iodized oils usually given in areas with frank deficiency Maternal Iodine Intake– especially during the first two trimesters Low birth weight - children born <2500 grams (can also be an outcome if fetal deficiency occurred) Duration of breastfeeding or non-exclusive in first 6 months General nutrition status – esp. stunting Maternal education and literacy Water supply and sanitation Access to health care Livestock Survival and Agricultural Productivity Inadequate caring capacity for the child
Outcome	Clinical	Goitre- enlargement of the thyroid in response to iodine deficiency Cretenism- neurological (deaf-mutism, spastic diplegia, squint, mental retardation) and myxoedematous (dwarfism, mental retardation)
	Sub-clinical	Blood- Thyroid Stimulating Hormone (TSH) Thyroglobulin (a storage protein of thyroid hormones, secreted by the thyroid) Urine- Urinary Iodine

Sources: Process indicators from ;Outcome indicators from John’s notes P8 8 Table 7 Summary of IDD

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Most sensitive group used for detection of IDD: School age children

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Outcome Indicators for Iodine Deficiency Disorders
Cut-offs at the individual and population level

Indicator	Individual Level		Population Level (%) (to be defined as a public health problem)
Indicator	Moderate	Severe	Mild	Moderate	Severe
Goitre by Palpatation (school age children)	Grade 1 Palpable, not visible in normal position	Grade 2 Swelling in the neck, visible in normal position	ł 5 to <20%	ł 20 to <30%	ł 30%
Goitre by Ultrasonography (school age children)	?	?	ł 5 to <20% (>97^th %)	ł 20 to <30% (>97^th %)	ł 30% (>97^th %)
Urinary Iodine (school age children)	<5 ug/dL in a 24 hour collection	<2 ug/dL	50 – 99ug/g creatinine (median)	20 – 49ug/g creatinine (median)	<20ug/g creatinine (median)
TSH (neonates)	>5 mU/l whole blood	--	ł 3 to <20 % (>5mU/l whole blood)	ł 20 to <40 % (>5mU/l whole blood)	ł 40% (>5mU/l whole blood)
Thyroglobulin (entire population)	?	?	ł 10 to <20 (median)	ł 20 to <40 (median)	ł 40 (median)

Source: Individual level goitre from ICCIDD/ WHO/ UNICEF; Individual Level TSH from John’s notes p8 8 IDD Indicators ; Population level cut-offs from John’s notes p8 8 IDD Indicators;

The following is a preview to the suggested assessments and action taken when IDD is detected.

…Assessment

Assessment of IDD usually involves an estimate of goitre, usually in school age children athough it can be done for the entire population. It is important to also measure the prevalence of households that use iodized salt, if a household survey is performed. For a more sensitive measure, urinary iodine can be used.

…Action

Ensure that salt supply is iodized
Monitor actual salt content of iodine—starch solution testing kits are available (e.g. from UNICEF)
In severe situations, provide oral iodized oil, at least for pregnant women
Research is now underway into possible iodization of water supplies, but salt is usually a better approach.