The health effects of an insufficient iodine intake depend on the severity of the deficiency. The severity of iodine deficiency in the population can be classified on the basis of the median iodine concentration in urine (see table).
WHO classification of iodine supply, based on excretion of iodine in urine
Median iodine urine concentration [ µg/l)
Iodine intake
Iodine supply
School aged children and
adults
<20
insufficient
severe iodine deficiency
20-49
insufficient
moderate iodine deficiency
50-99
insufficient
mild iodine deficiency
100-199
adequate
adequate iodine supply
200-299
above requirements
likely adequate intake for pregnant women and breastfeeding mothers, but may contain a slight risk of more than adequate intake in the general population
≥ 300
excessive
Risk of adverse consequences to health (iodine-induced hyperthyroidism, autoimmune thyroid disorders)
Pregnant women
<150
insufficient
150 - 249
adequate
250 - 499
over the required amount
≥ 500
excessive
excessive means far above the amount needed to prevent and inhibit iodine deficiency
Breastfeeding mothers*
> 100
adequate
Infants <2 years
> 100
adequate
*Although breastfeeding mothers have the same requirement as pregnant women, the average adequate urine concentration is lower as iodine is also excreted via breastmilk.
According to World Health Organization (WHO, 2007), modified.
In adults, chronic iodine deficiency can result in the development of goitre either with or without nodules. Non-visible functional disorders of the thyroid are also common. Among those is hypothyroidism, which leads to reduced hormone production. Hypothyroidism can be associated with the following symptoms: Fatigue, weakness, reduced mental and physical ability, low metabolism with weight gain, slower heartbeat, dry and pale skin, brittle nails, apathy, concentration difficulties, loss of appetite, constipation and depressive moods.
In children and adolescents, iodine deficiency can lead to struma diffusa (goitre, enlargement of the thyroid) and the development of hypothyroidism. Other possible consequences of iodine deficiency include lowered mental capacity and delayed physical development. Studies have shown that treatment of mild to moderate iodine deficiency in children has led to improved cognitive performances.
Severe maternal iodine deficiency during pregnancy increases the risk of miscarriages and stillbirths, and deformity. In children it can lead to short stature, deaf-muteness and delayed mental development (symptoms of so called ‘cretinism’). Such a marked iodine deficiency does not exist among the German population, due to improved iodine intake.
There is still less research on the consequences of mild to moderate iodine deficiency during pregnancy. However, several studies have shown an association between a mild iodine deficiency during pregnancy and reduced cognitive abilities in children.
The health effects of an insufficient iodine intake depend on the severity of the deficiency. The severity of iodine deficiency in the population can be classified on the basis of the median iodine concentration in urine (see table).
WHO classification of iodine supply, based on excretion of iodine in urine
Median iodine urine concentration [ µg/l)
Iodine intake
Iodine supply
School aged children and
adults
<20
insufficient
severe iodine deficiency
20-49
insufficient
moderate iodine deficiency
50-99
insufficient
mild iodine deficiency
100-199
adequate
adequate iodine supply
200-299
above requirements
likely adequate intake for pregnant women and breastfeeding mothers, but may contain a slight risk of more than adequate intake in the general population
≥ 300
excessive
Risk of adverse consequences to health (iodine-induced hyperthyroidism, autoimmune thyroid disorders)
Pregnant women
<150
insufficient
150 - 249
adequate
250 - 499
over the required amount
≥ 500
excessive
excessive means far above the amount needed to prevent and inhibit iodine deficiency
Breastfeeding mothers*
> 100
adequate
Infants <2 years
> 100
adequate
*Although breastfeeding mothers have the same requirement as pregnant women, the average adequate urine concentration is lower as iodine is also excreted via breastmilk.
According to World Health Organization (WHO, 2007), modified.
In adults, chronic iodine deficiency can result in the development of goitre either with or without nodules. Non-visible functional disorders of the thyroid are also common. Among those is hypothyroidism, which leads to reduced hormone production. Hypothyroidism can be associated with the following symptoms: Fatigue, weakness, reduced mental and physical ability, low metabolism with weight gain, slower heartbeat, dry and pale skin, brittle nails, apathy, concentration difficulties, loss of appetite, constipation and depressive moods.
In children and adolescents, iodine deficiency can lead to struma diffusa (goitre, enlargement of the thyroid) and the development of hypothyroidism. Other possible consequences of iodine deficiency include lowered mental capacity and delayed physical development. Studies have shown that treatment of mild to moderate iodine deficiency in children has led to improved cognitive performances.
Severe maternal iodine deficiency during pregnancy increases the risk of miscarriages and stillbirths, and deformity. In children it can lead to short stature, deaf-muteness and delayed mental development (symptoms of so called ‘cretinism’). Such a marked iodine deficiency does not exist among the German population, due to improved iodine intake.
There is still less research on the consequences of mild to moderate iodine deficiency during pregnancy. However, several studies have shown an association between a mild iodine deficiency during pregnancy and reduced cognitive abilities in children.