Iodine deficiency, a significant global health concern, can lead to a range of disorders affecting growth and development. As reported by the World Health Organization, iodized salt has played a crucial role in combating this issue, with 88% of the global population now using iodized salt. This simple yet effective intervention has nearly doubled the number of countries with adequate iodine intake from 67 in 2003 to 118 in 2020. Despite this progress, iodine deficiency remains a challenge in 21 countries, highlighting the ongoing need for awareness and action.
Iodine Blood Test Types
Several types of blood tests can be used to assess iodine status and related thyroid function:
• Serum iodine test: Directly measures iodine levels in the blood, with a normal range of 40-92 ng/mL1
• Thyroid-stimulating hormone (TSH) and thyroid hormone tests: Indicate potential iodine deficiency indirectly2
• Thyroglobulin test: Used as a population measure of iodine nutrition status3
Special collection procedures using metal-free tubes are required to avoid contamination when testing blood iodine levels4. While these tests exist, other methods like urine iodine tests and radioactive iodine uptake tests are often preferred for assessing iodine status25. Blood tests for TSH and thyroid hormones are routinely used to screen newborns for congenital hypothyroidism, which can result from iodine deficiency6.
Symptoms of Iodine Deficiency
The most common sign of iodine deficiency is an enlarged thyroid gland, known as goiter. Other symptoms include fatigue, weight gain, sensitivity to cold, dry skin, hair loss, and impaired cognitive function12. In pregnant women, iodine deficiency can lead to serious complications such as miscarriage, stillbirth, and congenital abnormalities in newborns1. Severe deficiency during pregnancy may cause cretinism in babies, characterized by intellectual disability, stunted growth, and potential hearing and speech issues3. Fertility problems and slow heart rate are also associated with iodine deficiency4. These symptoms can be subtle and may overlap with other conditions, necessitating proper diagnosis through blood tests and physical examination.
Impact of Iodized Salt
The introduction of iodized salt has been a major public health triumph, with significant global impact. Since its inception in the United States in 1924, iodized salt programs have expanded worldwide, leading to a dramatic reduction in iodine deficiency disorders. The prevalence of clinical iodine deficiency disorders, as assessed by goiter rates, fell from 13.1% in 1993 to 3.2% in 20191. This intervention has prevented iodine deficiency disorders in 20.5 million newborns annually and is estimated to have raised average IQ by 15 points in previously iodine-deficient populations1. The resulting improvement in cognitive function has led to an approximate $33 billion global economic benefit, highlighting the far-reaching effects of this simple yet effective public health measure1.