This indicator allows an assessment of iodine deficiency at the population level. Iodine is an essential trace element that is present in the thyroid hormones, thyroxine and triiodotyronine. It occurs most frequently in areas where there is little iodine in the diet - typically, these are remote inland areas where no marine foods are eaten. Urinary iodine concentration in children aged 6-12 years is included as an additional indicator in the WHO Global reference list of 100 core health indicators.
How is it defined?
Although goitre assessment by palpation or ultrasound may be useful for assessing thyroid function, results are difficult to interpret once salt iodization programmes have started. The median urinary iodine concentration is considered to be the main indicator of iodine status for all age groups, because its measurement is relatively non-invasive, cost-efficient and easy to perform. Since most of the iodine absorbed by the body is excreted in the urine, it is considered to be a sensitive marker of current iodine intake and can reflect recent changes in iodine status. Median urinary iodine concentrations have been most commonly measured in school children aged 6-12 years, because it is easy to access this population.
What are the consequences and implications?
Iodine-deficiency disorders, which can start before birth, jeopardize children's mental health and often their very survival. During the neonatal period, childhood and adolescence, iodine-deficiency disorders can lead to hypothyroidism and hyperthyroidism. Serious iodine deficiency during pregnancy can result in stillbirth, spontaneous abortion and congenital abnormalities such as cretinism - a grave, irreversible form of mental retardation that affects people living in iodine-deficient areas of Africa and Asia. Of even greater significance is the less visible, yet pervasive, mental impairment that reduces intellectual capacity at home, in school and at work.
Cut-off values for public health significance in different target groups
Concentration cut-off values for public health significance
Iodine deficiency measured by median urinary iodine concentration (μg/L) in school-age children (≥6 years) a